Koha/Database.pm

   1 package Koha::Database;
   2
   3 # Copyright 2013 Catalyst IT
   4 # chrisc@catalyst.net.nz
   5 #
   6 # This file is part of Koha.
   7 #
   8 # Koha is free software; you can redistribute it and/or modify it under the
   9 # terms of the GNU General Public License as published by the Free Software
  10 # Foundation; either version 3 of the License, or (at your option) any later
  11 # version.
  12 #
  13 # Koha is distributed in the hope that it will be useful, but WITHOUT ANY
  14 # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  15 # A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License along
  18 # with Koha; if not, write to the Free Software Foundation, Inc.,
  19 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20
  21 =head1 NAME
  22
  23 Koha::Database
  24
  25 =head1 SYNOPSIS
  26
  27   use Koha::Database;
  28   my $database = Koha::Database->new();
  29   my $schema = $database->schema();
  30
  31 =head1 FUNCTIONS
  32
  33 =cut
  34
  35 use Modern::Perl;
  36 use Carp;
  37 use C4::Context;
  38 use base qw(Class::Accessor);
  39
  40 use vars qw($database);
  41
  42 __PACKAGE__->mk_accessors(qw( ));
  43
  44 # _new_schema
  45 # Internal helper function (not a method!). This creates a new
  46 # database connection from the data given in the current context, and
  47 # returns it.
  48 sub _new_schema {
  49
  50     require Koha::Schema;
  51     my $context = C4::Context->new();
  52
  53     # we are letting C4::Context->dbh not set the RaiseError handle attribute
  54     # for now for compatbility purposes
  55     my $schema = Koha::Schema->connect( sub { C4::Context->dbh }, { unsafe => 1 } );
  56     return $schema;
  57 }
  58
  59 =head2 schema
  60
  61     $schema = $database->schema;
  62
  63 Returns a database handle connected to the Koha database for the
  64 current context. If no connection has yet been made, this method
  65 creates one, and connects to the database.
  66
  67 This database handle is cached for future use: if you call
  68 C<$database-E<gt>schema> twice, you will get the same handle both
  69 times. If you need a second database handle, use C<&new_schema> and
  70 possibly C<&set_schema>.
  71
  72 =cut
  73
  74 sub schema {
  75     my $self = shift;
  76     my $sth;
  77
  78     if ( defined( $database->{schema} ) and $database->{schema}->storage->connected() ) {
  79         return $database->{schema};
  80     }
  81
  82     # No database handle or it died . Create one.
  83     $database->{schema} = &_new_schema();
  84     return $database->{schema};
  85 }
  86
  87 =head2 new_schema
  88
  89   $schema = $database->new_schema;
  90
  91 Creates a new connection to the Koha database for the current context,
  92 and returns the database handle (a C<DBI::db> object).
  93
  94 The handle is not saved anywhere: this method is strictly a
  95 convenience function; the point is that it knows which database to
  96 connect to so that the caller doesn't have to know.
  97
  98 =cut
  99
 100 #'
 101 sub new_schema {
 102     my $self = shift;
 103
 104     return &_new_schema();
 105 }
 106
 107 =head2 set_schema
 108
 109   $my_schema = $database->new_schema;
 110   $database->set_schema($my_schema);
 111   ...
 112   $database->restore_schema;
 113
 114 C<&set_schema> and C<&restore_schema> work in a manner analogous to
 115 C<&set_context> and C<&restore_context>.
 116
 117 C<&set_schema> saves the current database handle on a stack, then sets
 118 the current database handle to C<$my_schema>.
 119
 120 C<$my_schema> is assumed to be a good database handle.
 121
 122 =cut
 123
 124 sub set_schema {
 125     my $self       = shift;
 126     my $new_schema = shift;
 127
 128     # Save the current database handle on the handle stack.
 129     # We assume that $new_schema is all good: if the caller wants to
 130     # screw himself by passing an invalid handle, that's fine by
 131     # us.
 132     push @{ $database->{schema_stack} }, $database->{schema};
 133     $database->{schema} = $new_schema;
 134 }
 135
 136 =head2 restore_schema
 137
 138   $database->restore_schema;
 139
 140 Restores the database handle saved by an earlier call to
 141 C<$database-E<gt>set_schema>.
 142
 143 =cut
 144
 145 sub restore_schema {
 146     my $self = shift;
 147
 148     if ( $#{ $database->{schema_stack} } < 0 ) {
 149
 150         # Stack underflow
 151         die "SCHEMA stack underflow";
 152     }
 153
 154     # Pop the old database handle and set it.
 155     $database->{schema} = pop @{ $database->{schema_stack} };
 156
 157     # FIXME - If it is determined that restore_context should
 158     # return something, then this function should, too.
 159 }
 160
 161 =head2 EXPORT
 162
 163 None by default.
 164
 165
 166 =head1 AUTHOR
 167
 168 Chris Cormack, E<lt>chrisc@catalyst.net.nzE<gt>
 169
 170 =cut
 171
 172 1;
 173
 174 __END__