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DBIx::Class::Schema(3)               User Contributed Perl Documentation              DBIx::Class::Schema(3)



NAME
       DBIx::Class::Schema - composable schemas

SYNOPSIS
         package Library::Schema;
         use base qw/DBIx::Class::Schema/;

         # load all Result classes in Library/Schema/Result/
         __PACKAGE__->load_namespaces();

         package Library::Schema::Result::CD;
         use base qw/DBIx::Class::Core/;

         __PACKAGE__->load_components(qw/InflateColumn::DateTime/); # for example
         __PACKAGE__->table('cd');

         # Elsewhere in your code:
         my $schema1 = Library::Schema->connect(
           $dsn,
           $user,
           $password,
           { AutoCommit => 1 },
         );

         my $schema2 = Library::Schema->connect($coderef_returning_dbh);

         # fetch objects using Library::Schema::Result::DVD
         my $resultset = $schema1->resultset('DVD')->search( ... );
         my @dvd_objects = $schema2->resultset('DVD')->search( ... );

DESCRIPTION
       Creates database classes based on a schema. This is the recommended way to use DBIx::Class and allows
       you to use more than one concurrent connection with your classes.

       NB: If you're used to Class::DBI it's worth reading the "SYNOPSIS" carefully, as DBIx::Class does
       things a little differently. Note in particular which module inherits off which.

SETUP METHODS
   load_namespaces
       Arguments: %options?

         __PACKAGE__->load_namespaces();

         __PACKAGE__->load_namespaces(
            result_namespace => 'Res',
            resultset_namespace => 'RSet',
            default_resultset_class => '+MyDB::Othernamespace::RSet',
         );

       With no arguments, this method uses Module::Find to load all of the Result and ResultSet classes
       under the namespace of the schema from which it is called.  For example, "My::Schema" will by default
       find and load Result classes named "My::Schema::Result::*" and ResultSet classes named
       "My::Schema::ResultSet::*".

       ResultSet classes are associated with Result class of the same name.  For example,
       "My::Schema::Result::CD" will get the ResultSet class "My::Schema::ResultSet::CD" if it is present.

       Both Result and ResultSet namespaces are configurable via the "result_namespace" and
       "resultset_namespace" options.

       Another option, "default_resultset_class" specifies a custom default ResultSet class for Result
       classes with no corresponding ResultSet.

       All of the namespace and classname options are by default relative to the schema classname.  To
       specify a fully-qualified name, prefix it with a literal "+".  For example,
       "+Other::NameSpace::Result".

       Warnings

       You will be warned if ResultSet classes are discovered for which there are no matching Result classes
       like this:

         load_namespaces found ResultSet class $classname with no corresponding Result class

       If a Result class is found to already have a ResultSet class set using "resultset_class" to some
       other class, you will be warned like this:

         We found ResultSet class '$rs_class' for '$result', but it seems
         that you had already set '$result' to use '$rs_set' instead

       Examples

         # load My::Schema::Result::CD, My::Schema::Result::Artist,
         #    My::Schema::ResultSet::CD, etc...
         My::Schema->load_namespaces;

         # Override everything to use ugly names.
         # In this example, if there is a My::Schema::Res::Foo, but no matching
         #   My::Schema::RSets::Foo, then Foo will have its
         #   resultset_class set to My::Schema::RSetBase
         My::Schema->load_namespaces(
           result_namespace => 'Res',
           resultset_namespace => 'RSets',
           default_resultset_class => 'RSetBase',
         );

         # Put things in other namespaces
         My::Schema->load_namespaces(
           result_namespace => '+Some::Place::Results',
           resultset_namespace => '+Another::Place::RSets',
         );

       To search multiple namespaces for either Result or ResultSet classes, use an arrayref of namespaces
       for that option.  In the case that the same result (or resultset) class exists in multiple
       namespaces, later entries in the list of namespaces will override earlier ones.

         My::Schema->load_namespaces(
           # My::Schema::Results_C::Foo takes precedence over My::Schema::Results_B::Foo :
           result_namespace => [ 'Results_A', 'Results_B', 'Results_C' ],
           resultset_namespace => [ '+Some::Place::RSets', 'RSets' ],
         );

   load_classes
       Arguments: @classes?, { $namespace => [ @classes ] }+

       "load_classes" is an alternative method to "load_namespaces", both of which serve similar purposes,
       each with different advantages and disadvantages.  In the general case you should use
       "load_namespaces", unless you need to be able to specify that only specific classes are loaded at
       runtime.

       With no arguments, this method uses Module::Find to find all classes under the schema's namespace.
       Otherwise, this method loads the classes you specify (using use), and registers them (using
       "register_class").

       It is possible to comment out classes with a leading "#", but note that perl will think it's a
       mistake (trying to use a comment in a qw list), so you'll need to add "no warnings 'qw';" before your
       load_classes call.

       If any classes found do not appear to be Result class files, you will get the following warning:

          Failed to load $comp_class. Can't find source_name method. Is
          $comp_class really a full DBIC result class? Fix it, move it elsewhere,
          or make your load_classes call more specific.

       Example:

         My::Schema->load_classes(); # loads My::Schema::CD, My::Schema::Artist,
                                     # etc. (anything under the My::Schema namespace)

         # loads My::Schema::CD, My::Schema::Artist, Other::Namespace::Producer but
         # not Other::Namespace::LinerNotes nor My::Schema::Track
         My::Schema->load_classes(qw/ CD Artist #Track /, {
           Other::Namespace => [qw/ Producer #LinerNotes /],
         });

   storage_type
       Arguments: $storage_type|{$storage_type, \%args}
       Return value: $storage_type|{$storage_type, \%args}
       Default value: DBIx::Class::Storage::DBI

       Set the storage class that will be instantiated when "connect" is called.  If the classname starts
       with "::", the prefix "DBIx::Class::Storage" is assumed by "connect".

       You want to use this to set subclasses of DBIx::Class::Storage::DBI in cases where the appropriate
       subclass is not autodetected.

       If your storage type requires instantiation arguments, those are defined as a second argument in the
       form of a hashref and the entire value needs to be wrapped into an arrayref or a hashref.  We support
       both types of refs here in order to play nice with your Config::[class] or your choice. See
       DBIx::Class::Storage::DBI::Replicated for an example of this.

   exception_action
       Arguments: $code_reference
       Return value: $code_reference
       Default value: None

       When "throw_exception" is invoked and "exception_action" is set to a code reference, this reference
       will be called instead of "throw" in DBIx::Class::Exception, with the exception message passed as the
       only argument.

       Your custom throw code must rethrow the exception, as "throw_exception" is an integral part of DBIC's
       internal execution control flow.

       Example:

          package My::Schema;
          use base qw/DBIx::Class::Schema/;
          use My::ExceptionClass;
          __PACKAGE__->exception_action(sub { My::ExceptionClass->throw(@_) });
          __PACKAGE__->load_classes;

          # or:
          my $schema_obj = My::Schema->connect( .... );
          $schema_obj->exception_action(sub { My::ExceptionClass->throw(@_) });

   stacktrace
       Arguments: boolean

       Whether "throw_exception" should include stack trace information.  Defaults to false normally, but
       defaults to true if $ENV{DBIC_TRACE} is true.

   sqlt_deploy_hook
       Arguments: $sqlt_schema

       An optional sub which you can declare in your own Schema class that will get passed the
       SQL::Translator::Schema object when you deploy the schema via "create_ddl_dir" or "deploy".

       For an example of what you can do with this, see "Adding Indexes And Functions To Your SQL" in
       DBIx::Class::Manual::Cookbook.

       Note that sqlt_deploy_hook is called by "deployment_statements", which in turn is called before
       "deploy". Therefore the hook can be used only to manipulate the SQL::Translator::Schema object before
       it is turned into SQL fed to the database. If you want to execute post-deploy statements which can
       not be generated by SQL::Translator, the currently suggested method is to overload "deploy" and use
       dbh_do.

METHODS
   connect
       Arguments: @connectinfo
       Return Value: $new_schema

       Creates and returns a new Schema object. The connection info set on it is used to create a new
       instance of the storage backend and set it on the Schema object.

       See "connect_info" in DBIx::Class::Storage::DBI for DBI-specific syntax on the @connectinfo argument,
       or DBIx::Class::Storage in general.

       Note that "connect_info" expects an arrayref of arguments, but "connect" does not. "connect" wraps
       its arguments in an arrayref before passing them to "connect_info".

       Overloading

       "connect" is a convenience method. It is equivalent to calling
       $schema->clone->connection(@connectinfo). To write your own overloaded version, overload "connection"
       instead.

   resultset
       Arguments: $source_name
       Return Value: $resultset

         my $rs = $schema->resultset('DVD');

       Returns the DBIx::Class::ResultSet object for the registered source name.

   sources
       Return Value: @source_names

         my @source_names = $schema->sources;

       Lists names of all the sources registered on this Schema object.

   source
       Arguments: $source_name
       Return Value: $result_source

         my $source = $schema->source('Book');

       Returns the DBIx::Class::ResultSource object for the registered source name.

   class
       Arguments: $source_name
       Return Value: $classname

         my $class = $schema->class('CD');

       Retrieves the Result class name for the given source name.

   txn_do
       Arguments: $coderef, @coderef_args?
       Return Value: The return value of $coderef

       Executes $coderef with (optional) arguments @coderef_args atomically, returning its result (if any).
       Equivalent to calling $schema->storage->txn_do.  See "txn_do" in DBIx::Class::Storage for more
       information.

       This interface is preferred over using the individual methods "txn_begin", "txn_commit", and
       "txn_rollback" below.

       WARNING: If you are connected with "AutoCommit => 0" the transaction is considered nested, and you
       will still need to call "txn_commit" to write your changes when appropriate. You will also want to
       connect with "auto_savepoint => 1" to get partial rollback to work, if the storage driver for your
       database supports it.

       Connecting with "AutoCommit => 1" is recommended.

   txn_scope_guard
       Runs "txn_scope_guard" on the schema's storage. See "txn_scope_guard" in DBIx::Class::Storage.

   txn_begin
       Begins a transaction (does nothing if AutoCommit is off). Equivalent to calling
       $schema->storage->txn_begin. See "txn_begin" in DBIx::Class::Storage for more information.

   txn_commit
       Commits the current transaction. Equivalent to calling $schema->storage->txn_commit. See "txn_commit"
       in DBIx::Class::Storage for more information.

   txn_rollback
       Rolls back the current transaction. Equivalent to calling $schema->storage->txn_rollback. See
       "txn_rollback" in DBIx::Class::Storage for more information.

   storage
         my $storage = $schema->storage;

       Returns the DBIx::Class::Storage object for this Schema. Grab this if you want to turn on SQL
       statement debugging at runtime, or set the quote character. For the default storage, the
       documentation can be found in DBIx::Class::Storage::DBI.

   populate
       Arguments: $source_name, \@data;
       Return value: \@$objects | nothing

       Pass this method a resultsource name, and an arrayref of arrayrefs. The arrayrefs should contain a
       list of column names, followed by one or many sets of matching data for the given columns.

       In void context, "insert_bulk" in DBIx::Class::Storage::DBI is used to insert the data, as this is a
       fast method. However, insert_bulk currently assumes that your datasets all contain the same type of
       values, using scalar references in a column in one row, and not in another will probably not work.

       Otherwise, each set of data is inserted into the database using "create" in DBIx::Class::ResultSet,
       and a arrayref of the resulting row objects is returned.

       e.g.

         $schema->populate('Artist', [
           [ qw/artistid name/ ],
           [ 1, 'Popular Band' ],
           [ 2, 'Indie Band' ],
           ...
         ]);

       Since wantarray context is basically the same as looping over $rs->create(...)  you won't see any
       performance benefits and in this case the method is more for convenience. Void context sends the
       column information directly to storage using <DBI>s bulk insert method. So the performance will be
       much better for storages that support this method.

       Because of this difference in the way void context inserts rows into your database you need to note
       how this will effect any loaded components that override or augment insert.  For example if you are
       using a component such as DBIx::Class::UUIDColumns to populate your primary keys you MUST use
       wantarray context if you want the PKs automatically created.

   connection
       Arguments: @args
       Return Value: $new_schema

       Similar to "connect" except sets the storage object and connection data in-place on the Schema class.
       You should probably be calling "connect" to get a proper Schema object instead.

       Overloading

       Overload "connection" to change the behaviour of "connect".

   compose_namespace
       Arguments: $target_namespace, $additional_base_class?
       Retur Value: $new_schema

       For each DBIx::Class::ResultSource in the schema, this method creates a class in the target namespace
       (e.g. $target_namespace::CD, $target_namespace::Artist) that inherits from the corresponding classes
       attached to the current schema.

       It also attaches a corresponding DBIx::Class::ResultSource object to the new $schema object. If
       $additional_base_class is given, the new composed classes will inherit from first the corresponding
       class from the current schema then the base class.

       For example, for a schema with My::Schema::CD and My::Schema::Artist classes,

         $schema->compose_namespace('My::DB', 'Base::Class');
         print join (', ', @My::DB::CD::ISA) . "\n";
         print join (', ', @My::DB::Artist::ISA) ."\n";

       will produce the output

         My::Schema::CD, Base::Class
         My::Schema::Artist, Base::Class

   svp_begin
       Creates a new savepoint (does nothing outside a transaction).  Equivalent to calling
       $schema->storage->svp_begin.  See "svp_begin" in DBIx::Class::Storage for more information.

   svp_release
       Releases a savepoint (does nothing outside a transaction).  Equivalent to calling
       $schema->storage->svp_release.  See "svp_release" in DBIx::Class::Storage for more information.

   svp_rollback
       Rollback to a savepoint (does nothing outside a transaction).  Equivalent to calling
       $schema->storage->svp_rollback.  See "svp_rollback" in DBIx::Class::Storage for more information.

   clone
       Arguments: %attrs?
       Return Value: $new_schema

       Clones the schema and its associated result_source objects and returns the copy. The resulting copy
       will have the same attributes as the source schema, except for those attributes explicitly overriden
       by the provided %attrs.

   throw_exception
       Arguments: $message

       Throws an exception. Obeys the exemption rules of DBIx::Class::Carp to report errors from outer-user's outeruser's
       user's perspective. See "exception_action" for details on overriding this method's behavior.  If
       "stacktrace" is turned on, "throw_exception"'s default behavior will provide a detailed stack trace.

   deploy
       Arguments: \%sqlt_args, $dir

       Attempts to deploy the schema to the current storage using SQL::Translator.

       See "METHODS" in SQL::Translator for a list of values for "\%sqlt_args".  The most common value for
       this would be "{ add_drop_table => 1 }" to have the SQL produced include a "DROP TABLE" statement for
       each table created. For quoting purposes supply "quote_table_names" and "quote_field_names".

       Additionally, the DBIx::Class parser accepts a "sources" parameter as a hash ref or an array ref,
       containing a list of source to deploy. If present, then only the sources listed will get deployed.
       Furthermore, you can use the "add_fk_index" parser parameter to prevent the parser from creating an
       index for each FK.

   deployment_statements
       Arguments: See "deployment_statements" in DBIx::Class::Storage::DBI
       Return value: $listofstatements

       A convenient shortcut to "$self->storage->deployment_statements($self, @args)".  Returns the SQL
       statements used by "deploy" and "deploy" in DBIx::Class::Schema::Storage.

   create_ddl_dir
       Arguments: See "create_ddl_dir" in DBIx::Class::Storage::DBI

       A convenient shortcut to "$self->storage->create_ddl_dir($self, @args)".

       Creates an SQL file based on the Schema, for each of the specified database types, in the given
       directory.

   ddl_filename
       Arguments: $database-type, $version, $directory, $preversion
       Return value: $normalised_filename

         my $filename = $table->ddl_filename($type, $version, $dir, $preversion)

       This method is called by "create_ddl_dir" to compose a file name out of the supplied directory,
       database type and version number. The default file name format is: "$dir$schema-$version-$type.sql".

       You may override this method in your schema if you wish to use a different format.

        WARNING

        Prior to DBIx::Class version 0.08100 this method had a different signature:

           my $filename = $table->ddl_filename($type, $dir, $version, $preversion)

        In recent versions variables $dir and $version were reversed in order to
        bring the signature in line with other Schema/Storage methods. If you
        really need to maintain backward compatibility, you can do the following
        in any overriding methods:

           ($dir, $version) = ($version, $dir) if ($DBIx::Class::VERSION < 0.08100);

   thaw
       Provided as the recommended way of thawing schema objects. You can call "Storable::thaw" directly if
       you wish, but the thawed objects will not have a reference to any schema, so are rather useless.

   freeze
       This doesn't actually do anything more than call "nfreeze" in Storable, it is just provided here for
       symmetry.

   dclone
       Arguments: $object
       Return Value: dcloned $object

       Recommended way of dcloning DBIx::Class::Row and DBIx::Class::ResultSet objects so their references
       to the schema object (which itself is not cloned) are properly maintained.

   schema_version
       Returns the current schema class' $VERSION in a normalised way.

   register_class
       Arguments: $moniker, $component_class

       This method is called by "load_namespaces" and "load_classes" to install the found classes into your
       Schema. You should be using those instead of this one.

       You will only need this method if you have your Result classes in files which are not named after the
       packages (or all in the same file). You may also need it to register classes at runtime.

       Registers a class which isa DBIx::Class::ResultSourceProxy. Equivalent to calling:

         $schema->register_source($moniker, $component_class->result_source_instance);

   register_source
       Arguments: $moniker, $result_source

       This method is called by "register_class".

       Registers the DBIx::Class::ResultSource in the schema with the given moniker.

   unregister_source
       Arguments: $moniker

       Removes the DBIx::Class::ResultSource from the schema for the given moniker.

   register_extra_source
       Arguments: $moniker, $result_source

       As "register_source" but should be used if the result class already has a source and you want to
       register an extra one.

   compose_connection (DEPRECATED)
       Arguments: $target_namespace, @db_info
       Return Value: $new_schema

       DEPRECATED. You probably wanted compose_namespace.

       Actually, you probably just wanted to call connect.

AUTHORS
       Matt S. Trout <mst@shadowcatsystems.co.uk>

LICENSE
       You may distribute this code under the same terms as Perl itself.



perl v5.16.2                                     2012-10-18                           DBIx::Class::Schema(3)