X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FManual%2FIntro.pod;fp=lib%2FDBIx%2FClass%2FManual%2FIntro.pod;h=d27a24ae346e3ec749dd15b1b37213f7d728b71f;hb=fe0708a2d68b5d34b6bc6f7e70164c3e569f1dd0;hp=5414e0864b57de9b5c3d2374e90dea9a8af4f97b;hpb=01272eb81fe3a43e0a2f7befa465cc669945d543;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Manual/Intro.pod b/lib/DBIx/Class/Manual/Intro.pod index 5414e08..d27a24a 100644 --- a/lib/DBIx/Class/Manual/Intro.pod +++ b/lib/DBIx/Class/Manual/Intro.pod @@ -74,7 +74,8 @@ L objects. Let's look at how you can set and use your first native L tree. First we'll see how you can set up your classes yourself. If you want them to -be auto-discovered, just skip to the next section, which shows you how to use +be auto-discovered, just skip to the L, which shows you how to use L. =head2 Setting it up manually @@ -114,6 +115,10 @@ automatic row ordering: __PACKAGE__->load_components(qw/ Ordered /); __PACKAGE__->position_column('rank'); +Ordered will refer to a field called 'position' unless otherwise directed. Here you are defining +the ordering field to be named 'rank'. (NOTE: Insert errors may occur if you use the Ordered +component, but have not defined a position column or have a 'position' field in your row.) + Set the table for your class: __PACKAGE__->table('album'); @@ -187,24 +192,37 @@ foreign key: See L for more information about the various types of available relationships and how you can design your own. -=head2 Using L +=head2 Using DBIx::Class::Schema::Loader -This is an external module, and not part of the L distribution. -Like L, it inspects your database, and automatically creates -classes for all the tables in your database. Here's a simple setup: +This module (L) is an external module, and not part +of the L distribution. It inspects your database, and automatically +creates classes for all the tables in your schema. - package My::Schema; - use base qw/DBIx::Class::Schema::Loader/; +The simplest way to use it is via the L script from the +L distribution. For example: + + $ dbicdump -o dump_directory=./lib \ + -o components='["InflateColumn::DateTime"]' \ + MyApp::Schema dbi:mysql:mydb user pass - __PACKAGE__->loader_options( relationships => 1 ); +If you have a mixed-case database, use the C option, e.g.: - 1; + $ dbicdump -o dump_directory=./lib -o preserve_case=1 \ + -o components='["InflateColumn::DateTime"]' \ + MyApp::Schema dbi:mysql:mydb user pass -The actual autoloading process will occur when you create a connected instance -of your schema below. +If you are using L, then you can use the helper that comes with +L: -See the L documentation for more information on its -many options. + $ script/myapp_create.pl model MyDB DBIC::Schema MyDB::Schema \ + create=static moniker_map='{ foo => "FOO" }' dbi:SQLite:./myapp.db \ + on_connect_do='PRAGMA foreign_keys=ON' quote_char='"' + +See L for more information on this +helper. + +See the L and L +documentation for more information on the many loader options. =head2 Connecting @@ -236,7 +254,7 @@ a special fifth argument to connect: { on_connect_do => \@on_connect_sql_statments } ); -See L for more information about +See L for more information about this and other special C-time options. =head3 Via a database handle @@ -397,6 +415,53 @@ L. =head1 NOTES +=head2 The Significance and Importance of Primary Keys + +The concept of a L in +DBIx::Class warrants special discussion. The formal definition (which somewhat +resembles that of a classic RDBMS) is I. However this is where the +similarity ends. Any time you call a CRUD operation on a row (e.g. +L, +L, +L, +etc.) DBIx::Class will use the values of of the +L columns to populate +the C clause necessary to accomplish the operation. This is why it is +important to declare a L +on all your result sources B. +In a pinch one can always declare each row identifiable by all its columns: + + __PACKAGE__->set_primary_keys (__PACKAGE__->columns); + +Note that DBIx::Class is smart enough to store a copy of the PK values before +any row-object changes take place, so even if you change the values of PK +columns the C clause will remain correct. + +If you elect not to declare a C, DBIx::Class will behave correctly +by throwing exceptions on any row operation that relies on unique identifiable +rows. If you inherited datasets with multiple identical rows in them, you can +still operate with such sets provided you only utilize +L CRUD methods: +L, +L, +L + +For example, the following would not work (assuming C does not have +a declared PK): + + my $row = $schema->resultset('People') + ->search({ last_name => 'Dantes' }) + ->next; + $row->update({ children => 2 }); # <-- exception thrown because $row isn't + # necessarily unique + +So instead the following should be done: + + $schema->resultset('People') + ->search({ last_name => 'Dantes' }) + ->update({ children => 2 }); # <-- update's ALL Dantes to have children of 2 + =head2 Problems on RHEL5/CentOS5 There used to be an issue with the system perl on Red Hat Enterprise