(DISTFILES): Comment out a few missing files.

[mono-project.git] / mcs / class / System.Data / System.Data / DataRow.cs

//
// System.Data.DataRow.cs
//
// Author:
//   Rodrigo Moya <rodrigo@ximian.com>
//   Daniel Morgan <danmorg@sc.rr.com>
//   Tim Coleman <tim@timcoleman.com>
//   Ville Palo <vi64pa@koti.soon.fi>
//   Alan Tam Siu Lung <Tam@SiuLung.com>
//
// (C) Ximian, Inc 2002
// (C) Daniel Morgan 2002, 2003
// Copyright (C) 2002 Tim Coleman
//

//
// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Collections;
using System.Globalization;
using System.Xml;

namespace System.Data {
        /// <summary>
        /// Represents a row of data in a DataTable.
        /// </summary>
        [Serializable]
        public class DataRow
        {
                #region Fields

                private DataTable _table;

                internal int _original = -1;
                internal int _current = -1;
                internal int _proposed = -1;

                private ArrayList _columnErrors;
                private string rowError;
                private DataRowState rowState;
                internal int xmlRowID = 0;
                internal bool _nullConstraintViolation;
                private string _nullConstraintMessage;
                private bool editing = false;
                private bool _hasParentCollection;
                private bool _inChangingEvent;
                private int _rowId;

                private XmlDataDocument.XmlDataElement mappedElement;
                internal bool _inExpressionEvaluation = false;

                #endregion // Fields

                #region Constructors

                /// <summary>
                /// This member supports the .NET Framework infrastructure and is not intended to be 
                /// used directly from your code.
                /// </summary>
                protected internal DataRow (DataRowBuilder builder)
                {
                        _table = builder.Table;
                        // Get the row id from the builder.
                        _rowId = builder._rowId;

                        _proposed = _table.RecordCache.NewRecord();
                        // Initialise the data columns of the row with the dafault values, if any 
                        // TODO : should proposed version be available immediately after record creation ?
                        foreach(DataColumn column in _table.Columns) {
                                column.DataContainer.CopyValue(_table.DefaultValuesRowIndex,_proposed);
                        }
                        
                        rowError = String.Empty;

                        //on first creating a DataRow it is always detached.
                        rowState = DataRowState.Detached;
                        
                        ArrayList aiColumns = _table.Columns.AutoIncrmentColumns;
                        foreach (DataColumn dc in aiColumns) {
                                this [dc] = dc.AutoIncrementValue();
                        }

                        // create mapped XmlDataElement
                        DataSet ds = _table.DataSet;
                        if (ds != null && ds._xmlDataDocument != null)
                                mappedElement = new XmlDataDocument.XmlDataElement (this, _table.Prefix, _table.TableName, _table.Namespace, ds._xmlDataDocument);
                }

                internal DataRow(DataTable table,int rowId)
                {
                        _table = table;
                        _rowId = rowId;
                }

                #endregion // Constructors

                #region Properties

                private ArrayList ColumnErrors
                {
                        get {
                                if (_columnErrors == null) {
                                        _columnErrors = new ArrayList();
                                }
                                return _columnErrors;
                        }

                        set {
                                _columnErrors = value;
                        }
                }

                /// <summary>
                /// Gets a value indicating whether there are errors in a row.
                /// </summary>
                public bool HasErrors {
                        get {
                                if (RowError != string.Empty)
                                        return true;

                                foreach(String columnError in ColumnErrors) {
                                        if (columnError != null && columnError != string.Empty) {
                                                return true;
                                }
                                }
                                return false;
                        }
                }

                /// <summary>
                /// Gets or sets the data stored in the column specified by name.
                /// </summary>
                public object this[string columnName] {
                        get { return this[columnName, DataRowVersion.Default]; }
                        set {
                                int columnIndex = _table.Columns.IndexOf (columnName);
                                if (columnIndex == -1)
                                        throw new IndexOutOfRangeException ();
                                this[columnIndex] = value;
                        }
                }

                /// <summary>
                /// Gets or sets the data stored in specified DataColumn
                /// </summary>
                public object this[DataColumn column] {

                        get {
                                return this[column, DataRowVersion.Default];} 
                        set {
                                int columnIndex = _table.Columns.IndexOf (column);
                                if (columnIndex == -1)
                                        throw new ArgumentException ("The column does not belong to this table.");
                                this[columnIndex] = value;
                        }
                }

                /// <summary>
                /// Gets or sets the data stored in column specified by index.
                /// </summary>
                public object this[int columnIndex] {
                        get { return this[columnIndex, DataRowVersion.Default]; }
                        set {
                                if (columnIndex < 0 || columnIndex > _table.Columns.Count)
                                        throw new IndexOutOfRangeException ();
                                if (rowState == DataRowState.Deleted)
                                        throw new DeletedRowInaccessibleException ();

                                DataColumn column = _table.Columns[columnIndex];
                                _table.ChangingDataColumn (this, column, value);
                                
                                if (value == null && column.DataType != typeof(string)) {
                                        throw new ArgumentException("Cannot set column " + column.ColumnName + " to be null, Please use DBNull instead");
                                }
                                
                                CheckValue (value, column);

                                bool orginalEditing = editing;
                                if (!orginalEditing) {
                                        BeginEdit ();
                                }
                                
                                column[_proposed] = value;
                                _table.ChangedDataColumn (this, column, value);
                                if (!orginalEditing) {
                                        EndEdit ();
                                }
                        }
                }

                /// <summary>
                /// Gets the specified version of data stored in the named column.
                /// </summary>
                public object this[string columnName, DataRowVersion version] {
                        get {
                                int columnIndex = _table.Columns.IndexOf (columnName);
                                if (columnIndex == -1)
                                        throw new IndexOutOfRangeException ();
                                return this[columnIndex, version];
                        }
                }

                /// <summary>
                /// Gets the specified version of data stored in the specified DataColumn.
                /// </summary>
                public object this[DataColumn column, DataRowVersion version] {
                        get {
                                if (column.Table != Table)
                                        throw new ArgumentException ("The column does not belong to this table.");
                                int columnIndex = column.Ordinal;
                                return this[columnIndex, version];
                        }
                }

                /// <summary>
                /// Gets the data stored in the column, specified by index and version of the data to
                /// retrieve.
                /// </summary>
                public object this[int columnIndex, DataRowVersion version] {
                        get {
                                if (columnIndex < 0 || columnIndex > _table.Columns.Count)
                                        throw new IndexOutOfRangeException ();
                                // Accessing deleted rows
                                if (!_inExpressionEvaluation && rowState == DataRowState.Deleted && version != DataRowVersion.Original)
                                        throw new DeletedRowInaccessibleException ("Deleted row information cannot be accessed through the row.");
                                
                                DataColumn column = _table.Columns[columnIndex];
                                if (column.Expression != String.Empty) {
                                        object o = column.CompiledExpression.Eval (this);
                                        return Convert.ChangeType (o, column.DataType);
                                }
                                
                                int recordIndex = IndexFromVersion(version);

                                if (recordIndex >= 0) {
                                        return column[recordIndex];
                                }

                                if (rowState == DataRowState.Detached && version == DataRowVersion.Default && _proposed < 0)
                                        throw new RowNotInTableException("This row has been removed from a table and does not have any data.  BeginEdit() will allow creation of new data in this row.");
                                
                                throw new VersionNotFoundException (Locale.GetText ("There is no " + version.ToString () + " data to access."));
                        }
                }
                
                /// <summary>
                /// Gets or sets all of the values for this row through an array.
                /// </summary>
                public object[] ItemArray {
                        get { 
                                // row not in table
                                if (rowState == DataRowState.Detached)
                                        throw new RowNotInTableException("This row has been removed from a table and does not have any data.  BeginEdit() will allow creation of new data in this row.");
                                // Accessing deleted rows
                                if (rowState == DataRowState.Deleted)
                                        throw new DeletedRowInaccessibleException ("Deleted row information cannot be accessed through the row.");
                                
                                object[] items = new object[_table.Columns.Count];
                                foreach(DataColumn column in _table.Columns) {
                                        items[column.Ordinal] = column[_current];
                                }
                                return items;
                        }
                        set {
                                if (value.Length > _table.Columns.Count)
                                        throw new ArgumentException ();

                                if (rowState == DataRowState.Deleted)
                                        throw new DeletedRowInaccessibleException ();
                                
                                bool orginalEditing = editing;
                                if (!orginalEditing) { 
                                        BeginEdit ();
                                }
                                object newVal = null;
                                DataColumnChangeEventArgs e = new DataColumnChangeEventArgs();
                                foreach(DataColumn column in _table.Columns) {
                                        int i = column.Ordinal;
                                        newVal = (i < value.Length) ? value[i] : null;
                                        
                                        e.Initialize(this, column, newVal);
                                        _table.RaiseOnColumnChanged(e);
                                        CheckValue (e.ProposedValue, column);
                                        column[_proposed] = e.ProposedValue;
                                }
                                if (!orginalEditing) {
                                        EndEdit ();
                                }
                        }
                }

                /// <summary>
                /// Gets the current state of the row in regards to its relationship to the
                /// DataRowCollection.
                /// </summary>
                public DataRowState RowState {
                        get { 
                                return rowState; 
                        }
                }

                /// <summary>
                /// Gets the DataTable for which this row has a schema.
                /// </summary>
                public DataTable Table {
                        get { 
                                return _table; 
                        }
                }

                /// <summary>
                /// Gets and sets index of row. This is used from 
                /// XmlDataDocument.
                // </summary>
                internal int XmlRowID {
                        get { 
                                return xmlRowID; 
                        }
                        set { 
                                xmlRowID = value; 
                        }
                }
                
                /// <summary>
                /// Gets and sets index of row.
                // </summary>
                internal int RowID {
                        get { 
                                return _rowId; 
                        }
                        set { 
                                _rowId = value; 
                        }
                }

                #endregion

                #region Methods

                //FIXME?: Couldn't find a way to set the RowState when adding the DataRow
                //to a Datatable so I added this method. Delete if there is a better way.
                internal void AttachRow() {
                        if (_current >= 0) {
                                Table.RecordCache.DisposeRecord(_current);
                        }
                        _current = _proposed;
                        _proposed = -1;
                        rowState = DataRowState.Added;
                }

                //FIXME?: Couldn't find a way to set the RowState when removing the DataRow
                //from a Datatable so I added this method. Delete if there is a better way.
                internal void DetachRow() {
                        if (_proposed >= 0) {
                                _table.RecordCache.DisposeRecord(_proposed);
                                _proposed = -1;
                        }
                        _rowId = -1;
                        _hasParentCollection = false;
                        rowState = DataRowState.Detached;
                }

                private void CheckValue (object v, DataColumn col) 
                {               
                        if (_hasParentCollection && col.ReadOnly) {
                                throw new ReadOnlyException ();
                        }

                        if (v == null || v == DBNull.Value) {
                                if (col.AllowDBNull || col.AutoIncrement || col.DefaultValue != DBNull.Value) {
                                        return;
                                }

                                //Constraint violations during data load is raise in DataTable EndLoad
                                this._nullConstraintViolation = true;
                                if (this.Table._duringDataLoad) {
                                        this.Table._nullConstraintViolationDuringDataLoad = true;
                                }
                                _nullConstraintMessage = "Column '" + col.ColumnName + "' does not allow nulls.";
                        
                        }
                }

                internal void SetValuesFromDataRecord(IDataRecord record, int[] mapping)
                {
                        if ( mapping.Length > Table.Columns.Count)
                                throw new ArgumentException ();

//                      bool orginalEditing = editing;
//                      if (!orginalEditing) { 
//                              BeginEdit ();
//                      }
                        
                        if (!HasVersion(DataRowVersion.Proposed)) {
                                _proposed = Table.RecordCache.NewRecord();
                        }

                        try {
                                for(int i=0; i < mapping.Length; i++) {
                                        DataColumn column = Table.Columns[i];
                                        column.DataContainer.SetItemFromDataRecord(_proposed, record,mapping[i]);
                                        if ( column.AutoIncrement ) { 
                                                column.UpdateAutoIncrementValue(column.DataContainer.GetInt64(_proposed));
                                        }
                                }
                        }
                        catch (Exception e){
                                Table.RecordCache.DisposeRecord(_proposed);
                                _proposed = -1;
                                throw e;
                        }

//                      if (!orginalEditing) {
//                              EndEdit ();
//                      }
                }

                /// <summary>
                /// Gets or sets the custom error description for a row.
                /// </summary>
                public string RowError {
                        get { 
                                return rowError; 
                        }
                        set { 
                                rowError = value; 
                        }
                }

                internal int IndexFromVersion(DataRowVersion version)
                {
                        if (HasVersion(version))
                        {
                                int recordIndex;
                                switch (version) {
                                        case DataRowVersion.Default:
                                                if (editing || rowState == DataRowState.Detached) {
                                                        recordIndex = _proposed;
                                                }
                                                else {
                                                        recordIndex = _current;
                                                }
                                                break;
                                        case DataRowVersion.Proposed:
                                                recordIndex = _proposed;
                                                break;
                                        case DataRowVersion.Current:
                                                recordIndex = _current;
                                                break;
                                        case DataRowVersion.Original:
                                                recordIndex = _original;
                                                break;
                                        default:
                                                throw new ArgumentException ();
                                }
                                return recordIndex;
                        }
                        return -1;
                }

                internal XmlDataDocument.XmlDataElement DataElement {
                        get { return mappedElement; }
                        set { mappedElement = value; }
                }

                internal void SetOriginalValue (string columnName, object val)
                {
                        DataColumn column = _table.Columns[columnName];
                        _table.ChangingDataColumn (this, column, val);
                                
                        if (_original < 0 || _original == _current) { 
                                // This really creates a new record version if one does not exist
                                _original = Table.RecordCache.NewRecord();
                        }
                        CheckValue (val, column);
                        column[_original] = val;
                        rowState = DataRowState.Modified;
                }

                /// <summary>
                /// Commits all the changes made to this row since the last time AcceptChanges was
                /// called.
                /// </summary>
                public void AcceptChanges () 
                {
                        EndEdit(); // in case it hasn't been called
                        switch (rowState) {
                                case DataRowState.Unchanged:
                                        return;
                        case DataRowState.Added:
                        case DataRowState.Modified:
                                rowState = DataRowState.Unchanged;
                                break;
                        case DataRowState.Deleted:
                                _table.Rows.RemoveInternal (this);
                                DetachRow();
                                break;
                        case DataRowState.Detached:
                                throw new RowNotInTableException("Cannot perform this operation on a row not in the table.");
                        }
                        // Accept from detached
                        if (_original >= 0) {
                                Table.RecordCache.DisposeRecord(_original);
                        }
                        _original = _current;
                }

                /// <summary>
                /// Begins an edit operation on a DataRow object.
                /// </summary>
                public void BeginEdit () 
                {
                        if (_inChangingEvent)
                                throw new InRowChangingEventException("Cannot call BeginEdit inside an OnRowChanging event.");
                        if (rowState == DataRowState.Deleted)
                                throw new DeletedRowInaccessibleException ();
                        if (!HasVersion (DataRowVersion.Proposed)) {
                                _proposed = Table.RecordCache.NewRecord();
                                foreach(DataColumn column in Table.Columns) {
                                        column.DataContainer.CopyValue(_current,_proposed);
                                }
                        }
                        // setting editing to true stops validations on the row
                        editing = true;
                }

                /// <summary>
                /// Cancels the current edit on the row.
                /// </summary>
                public void CancelEdit () 
                {
                         if (_inChangingEvent)
                                throw new InRowChangingEventException("Cannot call CancelEdit inside an OnRowChanging event.");
                        editing = false;
                        if (HasVersion (DataRowVersion.Proposed)) {
                                Table.RecordCache.DisposeRecord(_proposed);
                                _proposed = -1;
                                if (rowState == DataRowState.Modified) {
                                    rowState = DataRowState.Unchanged;
                                }
                        }
                }

                /// <summary>
                /// Clears the errors for the row, including the RowError and errors set with
                /// SetColumnError.
                /// </summary>
                public void ClearErrors () 
                {
                        rowError = String.Empty;
                        ColumnErrors.Clear();
                }

                /// <summary>
                /// Deletes the DataRow.
                /// </summary>
                public void Delete () 
                {
                        _table.DeletingDataRow(this, DataRowAction.Delete);
                        switch (rowState) {
                        case DataRowState.Added:
                                // check what to do with child rows
                                CheckChildRows(DataRowAction.Delete);
                                _table.DeleteRowFromIndexes (this);
                                Table.Rows.RemoveInternal (this);

                                // if row was in Added state we move it to Detached.
                                DetachRow();
                                break;
                        case DataRowState.Deleted:
                                break;          
                        default:
                                // check what to do with child rows
                                CheckChildRows(DataRowAction.Delete);
                                _table.DeleteRowFromIndexes (this);
                                rowState = DataRowState.Deleted;
                                break;
                        }
                        _table.DeletedDataRow(this, DataRowAction.Delete);
                }

                // check the child rows of this row before deleting the row.
                private void CheckChildRows(DataRowAction action)
                {
                        
                        // in this method we find the row that this row is in a relation with them.
                        // in shortly we find all child rows of this row.
                        // then we function according to the DeleteRule of the foriegnkey.


                        // 1. find if this row is attached to dataset.
                        // 2. find if EnforceConstraints is true.
                        // 3. find if there are any constraint on the table that the row is in.
                        if (_table.DataSet != null && _table.DataSet.EnforceConstraints && _table.Constraints.Count > 0)
                        {
                                foreach (DataTable table in _table.DataSet.Tables)
                                {
                                        // loop on all ForeignKeyConstrain of the table.
                                        foreach (ForeignKeyConstraint fk in table.Constraints.ForeignKeyConstraints)
                                        {
                                                if (fk.RelatedTable == _table)
                                                {
                                                        Rule rule;
                                                        if (action == DataRowAction.Delete)
                                                                rule = fk.DeleteRule;
                                                        else
                                                                rule = fk.UpdateRule;
                                                        CheckChildRows(fk, action, rule);
                                                }                       
                                        }
                                }
                        }
                }

                private void CheckChildRows(ForeignKeyConstraint fkc, DataRowAction action, Rule rule)
                {                               
                        DataRow[] childRows = GetChildRows(fkc, DataRowVersion.Default);
                        switch (rule)
                        {
                                case Rule.Cascade:  // delete or change all relted rows.
                                        if (childRows != null)
                                        {
                                                for (int j = 0; j < childRows.Length; j++)
                                                {
                                                        // if action is delete we delete all child rows
                                                        if (action == DataRowAction.Delete)
                                                        {
                                                                if (childRows[j].RowState != DataRowState.Deleted)
                                                                        childRows[j].Delete();
                                                        }
                                                        // if action is change we change the values in the child row
                                                        else if (action == DataRowAction.Change)
                                                        {
                                                                // change only the values in the key columns
                                                                // set the childcolumn value to the new parent row value
                                                                for (int k = 0; k < fkc.Columns.Length; k++)
                                                                        childRows[j][fkc.Columns[k]] = this[fkc.RelatedColumns[k], DataRowVersion.Proposed];
                                                        }
                                                }
                                        }
                                        break;
                                case Rule.None: // throw an exception if there are any child rows.
                                        if (childRows != null)
                                        {
                                                for (int j = 0; j < childRows.Length; j++)
                                                {
                                                        if (childRows[j].RowState != DataRowState.Deleted)
                                                        {
                                                                string changeStr = "Cannot change this row because constraints are enforced on relation " + fkc.ConstraintName +", and changing this row will strand child rows.";
                                                                string delStr = "Cannot delete this row because constraints are enforced on relation " + fkc.ConstraintName +", and deleting this row will strand child rows.";
                                                                string message = action == DataRowAction.Delete ? delStr : changeStr;
                                                                throw new InvalidConstraintException(message);
                                                        }
                                                }
                                        }
                                        break;
                                case Rule.SetDefault: // set the values in the child rows to the defult value of the columns.
                                        if (childRows != null && childRows.Length > 0) {
                                                int defaultValuesRowIndex = childRows[0].Table.DefaultValuesRowIndex;
                                                foreach(DataRow childRow in childRows) {
                                                        if (childRow.RowState != DataRowState.Deleted) {
                                                                int defaultIdx = childRow.IndexFromVersion(DataRowVersion.Default);
                                                                foreach(DataColumn column in fkc.Columns) {
                                                                        column.DataContainer.CopyValue(defaultValuesRowIndex,defaultIdx);
                                                                }
                                                        }
                                                }
                                        }
                                        break;
                                case Rule.SetNull: // set the values in the child row to null.
                                        if (childRows != null)
                                        {
                                                for (int j = 0; j < childRows.Length; j++)
                                                {
                                                        DataRow child = childRows[j];
                                                        if (childRows[j].RowState != DataRowState.Deleted)
                                                        {
                                                                // set only the key columns to DBNull
                                                                for (int k = 0; k < fkc.Columns.Length; k++)
                                                                        child.SetNull(fkc.Columns[k]);
                                                        }
                                                }
                                        }
                                        break;
                        }

                }

                /// <summary>
                /// Ends the edit occurring on the row.
                /// </summary>
                public void EndEdit () 
                {
                        if (_inChangingEvent)
                                throw new InRowChangingEventException("Cannot call EndEdit inside an OnRowChanging event.");
                        if (rowState == DataRowState.Detached)
                        {
                                editing = false;
                                return;
                        }
                        
                        CheckReadOnlyStatus();
                        if (HasVersion (DataRowVersion.Proposed))
                        {
                                _inChangingEvent = true;
                                try
                                {
                                        _table.ChangingDataRow(this, DataRowAction.Change);
                                }
                                finally
                                {
                                        _inChangingEvent = false;
                                }
                                if (rowState == DataRowState.Unchanged)
                                        rowState = DataRowState.Modified;
                                
                                //Calling next method validates UniqueConstraints
                                //and ForeignKeys.
                                try
                                {
                                        if ((_table.DataSet == null || _table.DataSet.EnforceConstraints) && !_table._duringDataLoad)
                                                _table.Rows.ValidateDataRowInternal(this);
                                }
                                catch (Exception e)
                                {
                                        editing = false;
                                        Table.RecordCache.DisposeRecord(_proposed);
                                        _proposed = -1;
                                        throw e;
                                }

                                // Now we are going to check all child rows of current row.
                                // In the case the cascade is true the child rows will look up for
                                // parent row. since lookup in index is always on current,
                                // we have to move proposed version of current row to current
                                // in the case of check child row failure we are rolling 
                                // current row state back.
                                int backup = _current;
                                _current = _proposed;
                                bool editing_backup = editing;
                                editing = false;
                                try {
                                        // check all child rows.
                                        CheckChildRows(DataRowAction.Change);
                                        _proposed = -1;
                                        if (_original != backup) {
                                                Table.RecordCache.DisposeRecord(backup);
                                        }
                                }
                                catch (Exception ex) {
                                        // if check child rows failed - rollback to previous state
                                        // i.e. restore proposed and current versions
                                        _proposed = _current;
                                        _current = backup;
                                        editing = editing_backup;
                                        // since we failed - propagate an exception
                                        throw ex;
                                }
                                _table.ChangedDataRow(this, DataRowAction.Change);
                        }
                }

                /// <summary>
                /// Gets the child rows of this DataRow using the specified DataRelation.
                /// </summary>
                public DataRow[] GetChildRows (DataRelation relation) 
                {
                        return GetChildRows (relation, DataRowVersion.Current);
                }

                /// <summary>
                /// Gets the child rows of a DataRow using the specified RelationName of a
                /// DataRelation.
                /// </summary>
                public DataRow[] GetChildRows (string relationName) 
                {
                        return GetChildRows (Table.DataSet.Relations[relationName]);
                }

                /// <summary>
                /// Gets the child rows of a DataRow using the specified DataRelation, and
                /// DataRowVersion.
                /// </summary>
                public DataRow[] GetChildRows (DataRelation relation, DataRowVersion version) 
                {
                        if (relation == null)
                                return new DataRow[0];

                        if (this.Table == null || RowState == DataRowState.Detached)
                                throw new RowNotInTableException("This row has been removed from a table and does not have any data.  BeginEdit() will allow creation of new data in this row.");

                        if (relation.DataSet != this.Table.DataSet)
                                throw new ArgumentException();

                        if (relation.ChildKeyConstraint != null)
                                return GetChildRows (relation.ChildKeyConstraint, version);

                        ArrayList rows = new ArrayList();
                        DataColumn[] parentColumns = relation.ParentColumns;
                        DataColumn[] childColumns = relation.ChildColumns;
                        int numColumn = parentColumns.Length;
                        if (HasVersion(version))
                        {
                                object[] vals = new object[parentColumns.Length];
                                for (int i = 0; i < vals.Length; i++)
                                        vals[i] = this[parentColumns[i], version];
                                
                                foreach (DataRow row in relation.ChildTable.Rows) 
                                {
                                        bool allColumnsMatch = false;
                                        if (row.HasVersion(DataRowVersion.Default))
                                        {
                                                allColumnsMatch = true;
                                                for (int columnCnt = 0; columnCnt < numColumn; ++columnCnt) 
                                                {
                                                        if (!vals[columnCnt].Equals(
                                                                row[childColumns[columnCnt], DataRowVersion.Default])) 
                                                        {
                                                                allColumnsMatch = false;
                                                                break;
                                                        }
                                                }
                                        }
                                        if (allColumnsMatch) rows.Add(row);
                                }
                        }
                        DataRow[] result = relation.ChildTable.NewRowArray(rows.Count);
                        rows.CopyTo(result, 0);
                        return result;
                }

                /// <summary>
                /// Gets the child rows of a DataRow using the specified RelationName of a
                /// DataRelation, and DataRowVersion.
                /// </summary>
                public DataRow[] GetChildRows (string relationName, DataRowVersion version) 
                {
                        return GetChildRows (Table.DataSet.Relations[relationName], version);
                }

                private DataRow[] GetChildRows (ForeignKeyConstraint fkc, DataRowVersion version) 
                {
                        ArrayList rows = new ArrayList();
                        DataColumn[] parentColumns = fkc.RelatedColumns;
                        DataColumn[] childColumns = fkc.Columns;
                        int numColumn = parentColumns.Length;
                        if (HasVersion(version)) {
                                Index index = fkc.Index;
                                if (index != null) {
                                        // get the child rows from the index
                                        Node[] childNodes = index.FindAllSimple (parentColumns, IndexFromVersion(version));
                                        for (int i = 0; i < childNodes.Length; i++) {
                                                rows.Add (childNodes[i].Row);
                                        }
                                }
                                else { // if there is no index we search manualy.
                                        int curIndex = IndexFromVersion(DataRowVersion.Current);
                                        int tmpRecord = fkc.Table.RecordCache.NewRecord();

                                        try {
                                                for (int i = 0; i < numColumn; i++) {
                                                        // according to MSDN: the DataType value for both columns must be identical.
                                                        childColumns[i].DataContainer.CopyValue(parentColumns[i].DataContainer, curIndex, tmpRecord);
                                                }

                                                foreach (DataRow row in fkc.Table.Rows) {
                                                        bool allColumnsMatch = false;
                                                        if (row.HasVersion(DataRowVersion.Default)) {
                                                                allColumnsMatch = true;
                                                                int childIndex = row.IndexFromVersion(DataRowVersion.Default);
                                                                for (int columnCnt = 0; columnCnt < numColumn; ++columnCnt) {
                                                                        if (childColumns[columnCnt].DataContainer.CompareValues(childIndex, tmpRecord) != 0) {
                                                                                allColumnsMatch = false;
                                                                                break;
                                                                        }
                                                                }
                                                        }
                                                        if (allColumnsMatch) {
                                                                rows.Add(row);
                                                        }
                                                }
                                        }
                                        finally {
                                                fkc.Table.RecordCache.DisposeRecord(tmpRecord);
                                        }
                                }
                        }

                        DataRow[] result = fkc.Table.NewRowArray(rows.Count);
                        rows.CopyTo(result, 0);
                        return result;
                }

                /// <summary>
                /// Gets the error description of the specified DataColumn.
                /// </summary>
                public string GetColumnError (DataColumn column) 
                {
                        return GetColumnError (_table.Columns.IndexOf(column));
                }

                /// <summary>
                /// Gets the error description for the column specified by index.
                /// </summary>
                public string GetColumnError (int columnIndex) 
                {
                        if (columnIndex < 0 || columnIndex >= Table.Columns.Count)
                                throw new IndexOutOfRangeException ();

                        string retVal = null;
                        if (columnIndex < ColumnErrors.Count) {
                                retVal = (String) ColumnErrors[columnIndex];
                        }
                        return (retVal != null) ? retVal : String.Empty;
                }

                /// <summary>
                /// Gets the error description for the column, specified by name.
                /// </summary>
                public string GetColumnError (string columnName) 
                {
                        return GetColumnError (_table.Columns.IndexOf(columnName));
                }

                /// <summary>
                /// Gets an array of columns that have errors.
                /// </summary>
                public DataColumn[] GetColumnsInError () 
                {
                        ArrayList dataColumns = new ArrayList ();

                        int columnOrdinal = 0;
                        foreach(String columnError in ColumnErrors) {
                                if (columnError != null && columnError != String.Empty) {
                                        dataColumns.Add (_table.Columns[columnOrdinal]);
                                }
                                columnOrdinal++;
                        }

                        return (DataColumn[])(dataColumns.ToArray (typeof(DataColumn)));
                }

                /// <summary>
                /// Gets the parent row of a DataRow using the specified DataRelation.
                /// </summary>
                public DataRow GetParentRow (DataRelation relation) 
                {
                        return GetParentRow (relation, DataRowVersion.Current);
                }

                /// <summary>
                /// Gets the parent row of a DataRow using the specified RelationName of a
                /// DataRelation.
                /// </summary>
                public DataRow GetParentRow (string relationName) 
                {
                        return GetParentRow (relationName, DataRowVersion.Current);
                }

                /// <summary>
                /// Gets the parent row of a DataRow using the specified DataRelation, and
                /// DataRowVersion.
                /// </summary>
                public DataRow GetParentRow (DataRelation relation, DataRowVersion version) 
                {
                        DataRow[] rows = GetParentRows(relation, version);
                        if (rows.Length == 0) return null;
                        return rows[0];
                }

                /// <summary>
                /// Gets the parent row of a DataRow using the specified RelationName of a 
                /// DataRelation, and DataRowVersion.
                /// </summary>
                public DataRow GetParentRow (string relationName, DataRowVersion version) 
                {
                        return GetParentRow (Table.DataSet.Relations[relationName], version);
                }

                /// <summary>
                /// Gets the parent rows of a DataRow using the specified DataRelation.
                /// </summary>
                public DataRow[] GetParentRows (DataRelation relation) 
                {
                        return GetParentRows (relation, DataRowVersion.Current);
                }

                /// <summary>
                /// Gets the parent rows of a DataRow using the specified RelationName of a 
                /// DataRelation.
                /// </summary>
                public DataRow[] GetParentRows (string relationName) 
                {
                        return GetParentRows (relationName, DataRowVersion.Current);
                }

                /// <summary>
                /// Gets the parent rows of a DataRow using the specified DataRelation, and
                /// DataRowVersion.
                /// </summary>
                public DataRow[] GetParentRows (DataRelation relation, DataRowVersion version) 
                {
                        // TODO: Caching for better preformance
                        if (relation == null)
                                return new DataRow[0];

                        if (this.Table == null || RowState == DataRowState.Detached)
                                throw new RowNotInTableException("This row has been removed from a table and does not have any data.  BeginEdit() will allow creation of new data in this row.");

                        if (relation.DataSet != this.Table.DataSet)
                                throw new ArgumentException();

                        ArrayList rows = new ArrayList();
                        DataColumn[] parentColumns = relation.ParentColumns;
                        DataColumn[] childColumns = relation.ChildColumns;
                        int numColumn = parentColumns.Length;
                        if (HasVersion(version)) {
                                Index indx = relation.ParentTable.GetIndexByColumns (parentColumns);
                                if (indx != null && 
    (Table == null || Table.DataSet == null || 
     Table.DataSet.EnforceConstraints)) { // get the child rows from the index
                                        Node[] childNodes = indx.FindAllSimple(childColumns, IndexFromVersion(version));
                                        for (int i = 0; i < childNodes.Length; i++) {
                                                rows.Add (childNodes[i].Row);
                                        }
                                }
                                else { // no index so we have to search manualy.
                                        int curIndex = IndexFromVersion(DataRowVersion.Current);
                                        int tmpRecord = relation.ParentTable.RecordCache.NewRecord();
                                        try {
                                                for (int i = 0; i < numColumn; i++) {
                                                        // according to MSDN: the DataType value for both columns must be identical.
                                                        parentColumns[i].DataContainer.CopyValue(childColumns[i].DataContainer, curIndex, tmpRecord);
                                                }

                                                foreach (DataRow row in relation.ParentTable.Rows) {
                                                        bool allColumnsMatch = false;
                                                        if (row.HasVersion(DataRowVersion.Default)) {
                                                                allColumnsMatch = true;
                                                                int parentIndex = row.IndexFromVersion(DataRowVersion.Default);
                                                                for (int columnCnt = 0; columnCnt < numColumn; columnCnt++) {
                                                                        if (parentColumns[columnCnt].DataContainer.CompareValues(parentIndex, tmpRecord) != 0) {
                                                                                allColumnsMatch = false;
                                                                                break;
                                                                        }
                                                                }
                                                        }
                                                        if (allColumnsMatch) {
                                                                rows.Add(row);
                                                        }
                                                }
                                        }
                                        finally {
                                                relation.ParentTable.RecordCache.DisposeRecord(tmpRecord);
                                        }
                                }
                        }

                        DataRow[] result = relation.ParentTable.NewRowArray(rows.Count);
                        rows.CopyTo(result, 0);
                        return result;
                }

                /// <summary>
                /// Gets the parent rows of a DataRow using the specified RelationName of a 
                /// DataRelation, and DataRowVersion.
                /// </summary>
                public DataRow[] GetParentRows (string relationName, DataRowVersion version) 
                {
                        return GetParentRows (Table.DataSet.Relations[relationName], version);
                }

                /// <summary>
                /// Gets a value indicating whether a specified version exists.
                /// </summary>
                public bool HasVersion (DataRowVersion version) 
                {
                        switch (version) {
                                case DataRowVersion.Default:
                                        if (rowState == DataRowState.Deleted && !_inExpressionEvaluation)
                                                return false;
                                        if (rowState == DataRowState.Detached)
                                                return _proposed >= 0;
                                        return true;
                                case DataRowVersion.Proposed:
                                        if (rowState == DataRowState.Deleted && !_inExpressionEvaluation)
                                                return false;
                                        return _proposed >= 0;
                                case DataRowVersion.Current:
                                        if ((rowState == DataRowState.Deleted && !_inExpressionEvaluation) || rowState == DataRowState.Detached)
                                                return false;
                                        return _current >= 0;
                                case DataRowVersion.Original:
                                        if (rowState == DataRowState.Detached)
                                                return false;
                                        return _original >= 0;
                        }
                        return false;
                }

                /// <summary>
                /// Gets a value indicating whether the specified DataColumn contains a null value.
                /// </summary>
                public bool IsNull (DataColumn column) 
                {
                        return IsNull(column, DataRowVersion.Default);
                }

                /// <summary>
                /// Gets a value indicating whether the column at the specified index contains a null
                /// value.
                /// </summary>
                public bool IsNull (int columnIndex) 
                {
                        return IsNull(Table.Columns[columnIndex]);
                }

                /// <summary>
                /// Gets a value indicating whether the named column contains a null value.
                /// </summary>
                public bool IsNull (string columnName) 
                {
                        return IsNull(Table.Columns[columnName]);
                }

                /// <summary>
                /// Gets a value indicating whether the specified DataColumn and DataRowVersion
                /// contains a null value.
                /// </summary>
                public bool IsNull (DataColumn column, DataRowVersion version) 
                {
                        return column.DataContainer.IsNull(IndexFromVersion(version));
                }

                /// <summary>
                /// Returns a value indicating whether all of the row columns specified contain a null value.
                /// </summary>
                internal bool IsNullColumns(DataColumn[] columns)
                {
                        bool allNull = true;
                        for (int i = 0; i < columns.Length; i++) 
                        {
                                if (!IsNull(columns[i])) 
                                {
                                        allNull = false;
                                        break;
                                }
                        }
                        return allNull;
                }

                /// <summary>
                /// Rejects all changes made to the row since AcceptChanges was last called.
                /// </summary>
                public void RejectChanges () 
                {
                        if (RowState == DataRowState.Detached)
                                throw new RowNotInTableException("This row has been removed from a table and does not have any data.  BeginEdit() will allow creation of new data in this row.");
                        // If original is null, then nothing has happened since AcceptChanges
                        // was last called.  We have no "original" to go back to.
                        if (HasVersion(DataRowVersion.Original)) {
                                if (_current >= 0 ) {
                                        Table.RecordCache.DisposeRecord(_current);
                                }
                                _current = _original;
                               
                                _table.ChangedDataRow (this, DataRowAction.Rollback);
                                CancelEdit ();
                                switch (rowState)
                                {
                                        case DataRowState.Added:
                                                _table.DeleteRowFromIndexes (this);
                                                _table.Rows.RemoveInternal (this);
                                                break;
                                        case DataRowState.Modified:
                                                if ((_table.DataSet == null || _table.DataSet.EnforceConstraints) && !_table._duringDataLoad)
                                                        _table.Rows.ValidateDataRowInternal(this);
                                                rowState = DataRowState.Unchanged;
                                                break;
                                        case DataRowState.Deleted:
                                                rowState = DataRowState.Unchanged;
                                                if ((_table.DataSet == null || _table.DataSet.EnforceConstraints) && !_table._duringDataLoad)
                                                        _table.Rows.ValidateDataRowInternal(this);
                                                break;
                                } 
                                
                        }                       
                        else {
                                // If rows are just loaded via Xml the original values are null.
                                // So in this case we have to remove all columns.
                                // FIXME: I'm not realy sure, does this break something else, but
                                // if so: FIXME ;)
                                
                                if ((rowState & DataRowState.Added) > 0)
                                {
                                        _table.DeleteRowFromIndexes (this);
                                        _table.Rows.RemoveInternal (this);
                                        // if row was in Added state we move it to Detached.
                                        DetachRow();
                                }
                        }
                }

                /// <summary>
                /// Sets the error description for a column specified as a DataColumn.
                /// </summary>
                public void SetColumnError (DataColumn column, string error) 
                {
                        SetColumnError (_table.Columns.IndexOf (column), error);
                }

                /// <summary>
                /// Sets the error description for a column specified by index.
                /// </summary>
                public void SetColumnError (int columnIndex, string error) 
                {
                        if (columnIndex < 0 || columnIndex >= Table.Columns.Count)
                                throw new IndexOutOfRangeException ();

                        while(ColumnErrors.Count < columnIndex) {
                                ColumnErrors.Add(null);
                        }
                        ColumnErrors.Add(error);
                }

                /// <summary>
                /// Sets the error description for a column specified by name.
                /// </summary>
                public void SetColumnError (string columnName, string error) 
                {
                        SetColumnError (_table.Columns.IndexOf (columnName), error);
                }

                /// <summary>
                /// Sets the value of the specified DataColumn to a null value.
                /// </summary>
                protected void SetNull (DataColumn column) 
                {
                        this[column] = DBNull.Value;
                }

                /// <summary>
                /// Sets the parent row of a DataRow with specified new parent DataRow.
                /// </summary>
                public void SetParentRow (DataRow parentRow) 
                {
                        SetParentRow(parentRow, null);
                }

                /// <summary>
                /// Sets the parent row of a DataRow with specified new parent DataRow and
                /// DataRelation.
                /// </summary>
                public void SetParentRow (DataRow parentRow, DataRelation relation) 
                {
                        if (_table == null || parentRow.Table == null || RowState == DataRowState.Detached)
                                throw new RowNotInTableException("This row has been removed from a table and does not have any data.  BeginEdit() will allow creation of new data in this row.");

                        if (parentRow != null && _table.DataSet != parentRow.Table.DataSet)
                                throw new ArgumentException();
                        
                        BeginEdit();
                        if (relation == null)
                        {
                                foreach (DataRelation parentRel in _table.ParentRelations)
                                {
                                        DataColumn[] childCols = parentRel.ChildKeyConstraint.Columns;
                                        DataColumn[] parentCols = parentRel.ChildKeyConstraint.RelatedColumns;
                                        
                                        for (int i = 0; i < parentCols.Length; i++)
                                        {
                                                if (parentRow == null)
                                                        this[childCols[i].Ordinal] = DBNull.Value;
                                                else
                                                        this[childCols[i].Ordinal] = parentRow[parentCols[i]];
                                        }
                                        
                                }
                        }
                        else
                        {
                                DataColumn[] childCols = relation.ChildKeyConstraint.Columns;
                                DataColumn[] parentCols = relation.ChildKeyConstraint.RelatedColumns;
                                        
                                for (int i = 0; i < parentCols.Length; i++)
                                {
                                        if (parentRow == null)
                                                this[childCols[i].Ordinal] = DBNull.Value;
                                        else
                                                this[childCols[i].Ordinal] = parentRow[parentCols[i]];
                                }
                        }
                        EndEdit();
                }
                
                //Copy all values of this DataaRow to the row parameter.
                internal void CopyValuesToRow(DataRow row)
                {
                        if (row == null)
                                throw new ArgumentNullException("row");
                        if (row == this)
                                throw new ArgumentException("'row' is the same as this object");

                        foreach(DataColumn column in Table.Columns) {
                                DataColumn targetColumn = row.Table.Columns[column.ColumnName];
                                //if a column with the same name exists in both rows copy the values
                                if(targetColumn != null) {
                                        int index = targetColumn.Ordinal;
                                        if (HasVersion(DataRowVersion.Original)) {
                                                if (row._original < 0) {
                                                        row._original = row.Table.RecordCache.NewRecord();
                                                }
                                                object val = column[_original];
                                                row.CheckValue(val, targetColumn);
                                                targetColumn[row._original] = val;
                                        }
                                        if (HasVersion(DataRowVersion.Current)) {
                                                if (row._current < 0) {
                                                        row._current = row.Table.RecordCache.NewRecord();
                                                }
                                                object val = column[_current];
                                                row.CheckValue(val, targetColumn);
                                                targetColumn[row._current] = val;
                                        }
                                        if (HasVersion(DataRowVersion.Proposed)) {
                                                if (row._proposed < 0) {
                                                        row._proposed = row.Table.RecordCache.NewRecord();
                                                }
                                                object val = column[row._proposed];
                                                row.CheckValue(val, targetColumn);
                                                targetColumn[row._proposed] = val;
                                        }
                                        
                                        //Saving the current value as the column value
                                        row[index] = targetColumn[row._current];
                                        
                                }
                        }
                        CopyState(row);
                }

                // Copy row state - rowState and errors
                internal void CopyState(DataRow row)
                {
                        row.rowState = RowState;
                        row.RowError = RowError;
                        row.ColumnErrors = (ArrayList)ColumnErrors.Clone();
                }

                internal bool IsRowChanged(DataRowState rowState) {
                        if((RowState & rowState) != 0)
                                return true;

                        //we need to find if child rows of this row changed.
                        //if yes - we should return true

                        // if the rowState is deleted we should get the original version of the row
                        // else - we should get the current version of the row.
                        DataRowVersion version = (rowState == DataRowState.Deleted) ? DataRowVersion.Original : DataRowVersion.Current;
                        int count = Table.ChildRelations.Count;
                        for (int i = 0; i < count; i++){
                                DataRelation rel = Table.ChildRelations[i];
                                DataRow[] childRows = GetChildRows(rel, version);
                                for (int j = 0; j < childRows.Length; j++){
                                        if (childRows[j].IsRowChanged(rowState))
                                                return true;
                                }
                        }

                        return false;
                }

                internal bool HasParentCollection
                {
                        get
                        {
                                return _hasParentCollection;
                        }
                        set
                        {
                                _hasParentCollection = value;
                        }
                }

                internal void CheckNullConstraints()
                {
                        if (_nullConstraintViolation) {
                                if (HasVersion(DataRowVersion.Proposed)) {
                                        foreach(DataColumn column in Table.Columns) {
                                                if (IsNull(column) && !column.AllowDBNull) {
                                                        throw new NoNullAllowedException(_nullConstraintMessage);
                                        }
                                }
                                }
                                _nullConstraintViolation = false;
                        }
                }
                
                internal void CheckReadOnlyStatus()
                {
                        if (HasVersion(DataRowVersion.Proposed)) {
                                int defaultIdx = IndexFromVersion(DataRowVersion.Default); 
                                foreach(DataColumn column in Table.Columns) {
                                        if ((column.DataContainer.CompareValues(defaultIdx,_proposed) != 0) && column.ReadOnly) {
                                        throw new ReadOnlyException();
                        }
                }
                        }                       
                }
        
                #endregion // Methods
        }

        

}