lib/dml/database_column_info.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Database column information.
  19  *
  20  * @package    core_dml
  21  * @copyright  2008 Petr Skoda (http://skodak.org)
  22  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23  */
  24
  25 defined('MOODLE_INTERNAL') || die();
  26
  27 /**
  28  * Detailed database field information.
  29  *
  30  * It is based on the adodb library's ADOFieldObject object.
  31  * 'column' does mean 'the field' here.
  32  *
  33  * @package    core_dml
  34  * @copyright  2008 Petr Skoda (http://skodak.org)
  35  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  36  *
  37  * @property-read string $name Name of column - lowercase.
  38  * @property-read string $type Driver dependent native data type. Not standardised, it's used to find meta_type.
  39  *
  40  * Max length:
  41  *  character type - number of characters
  42  *  blob - number of bytes
  43  *  integer - number of digits
  44  *  float - digits left from floating point
  45  *  boolean - 1
  46  * @property-read int    $max_length size of the database field, eg how much data can you put in there.
  47  *
  48  * @property-read int    $scale Scale of field, decimal points (float), null otherwise.
  49  * @property-read bool   $not_null true if the field is set to NOT NULL.
  50  * @property-read bool   $primary_key true if the field is the primary key. (usually 'id').
  51  * @property-read bool   $auto_increment True if field is autoincrementing or sequence.
  52  * @property-read bool   $binary True if the field is binary.
  53  * @property-read bool   $has_default True if the default value is defined.
  54  * @property-read string $default_value The default value (if defined).
  55  * @property-read bool   $unique True if the field values are unique, false if not.
  56  *
  57  * Standardised one character column type, uppercased and enumerated as follows:
  58  * R - counter (integer primary key)
  59  * I - integers
  60  * N - numbers (floats)
  61  * C - characters and strings
  62  * X - texts
  63  * B - binary blobs
  64  * L - boolean (1 bit)
  65  * T - timestamp - unsupported
  66  * D - date - unsupported
  67  * @property-read string $meta_type Standardised one character column type, uppercased and enumerated: R,I,N,C,X,B,L,T,D
  68  */
  69 class database_column_info {
  70
  71     /**
  72      * @var array The internal storage of column data.
  73      */
  74     protected $data;
  75
  76     /**
  77      * Magic set function.  This is a read only object and you aren't allowed to write to any variables.
  78      *
  79      * @param string $name ignored.
  80      * @param mixed $value ignored.
  81      * @throws coding_exception You are not allowed to set data on database_column_info
  82      */
  83     public function __set($name, $value) {
  84         throw new coding_exception('database_column_info is a ready only object to allow for faster caching.');
  85     }
  86
  87     /**
  88      * Magic get function.
  89      *
  90      * @param string $variablename variable name to return the value of.
  91      * @return mixed The variable contents.
  92      *
  93      * @throws coding_exception You cannot request a variable that is not allowed.
  94      */
  95     public function __get($variablename) {
  96         if (isset($this->data[$variablename]) || array_key_exists($variablename, $this->data)) {
  97             return $this->data[$variablename];
  98         }
  99         throw new coding_exception('Asked for a variable that is not available . ('.$variablename.').');
 100     }
 101
 102     /**
 103      * Magic isset function.
 104      *
 105      * @param string $variablename The name of the property to test if isset().
 106      * @return bool Whether the value is set or not.
 107      */
 108     public function __isset($variablename) {
 109         return isset($this->data[$variablename]);
 110     }
 111
 112     /**
 113      * Constructor
 114      *
 115      * @param mixed $data object or array with properties
 116      */
 117     public function __construct($data) {
 118         // Initialize all the allowed variables to null so the array key exists.
 119         $validelements = array('name', 'type', 'max_length', 'scale', 'not_null', 'primary_key',
 120                                'auto_increment', 'binary', 'has_default',  'default_value',
 121                                'unique', 'meta_type');
 122         foreach ($validelements as $element) {
 123             if (isset($data->$element)) {
 124                 $this->data[$element] = $data->$element;
 125             } else {
 126                 $this->data[$element] = null;
 127             }
 128         }
 129
 130         switch ($this->data['meta_type']) {
 131             case 'R': // normalise counters (usually 'id')
 132                 $this->data['binary']         = false;
 133                 $this->data['has_default']    = false;
 134                 $this->data['default_value']  = null;
 135                 $this->data['unique']         = true;
 136                 break;
 137             case 'C':
 138                 $this->data['auto_increment'] = false;
 139                 $this->data['binary']         = false;
 140                 break;
 141         }
 142     }
 143 }