NAME

DBIO::Schema - Schema class and connection container for DBIO applications

VERSION

version 0.900000

SYNOPSIS

package Library::Schema;
use base qw/DBIO::Schema/;

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

package Library::Schema::Result::CD;
use base qw/DBIO::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

DBIO::Schema is the central class for a DBIO application. It owns the registered result sources, mediates access to storage, and provides the usual entry points such as connect, resultset, and source.

Using a dedicated schema class is the normal way to structure a DBIO application, and it allows the same result classes to be used with more than one concurrent connection when needed.

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 DBIO::Storage::DBI for DBI-specific syntax on the @connectinfo argument, or DBIO::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 DBIO::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 DBIO::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 DBIO::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 DBIO::Storage.

txn_begin

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

txn_commit

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

txn_rollback

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

storage

my $storage = $schema->storage;

Returns the DBIO::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 DBIO::Storage::DBI.

populate

Arguments: $source_name, [ \@column_list, \@row_values+ ] | [ \%col_data+ ]
Return Value: \@result_objects (scalar context) | @result_objects (list context)

A convenience shortcut to "populate" in DBIO::ResultSet. Equivalent to:

$schema->resultset($source_name)->populate([...]);

NOTE: The context of this method call has an important effect on what is submitted to storage. In void context data is fed directly to fastpath insertion routines provided by the underlying storage (most often "execute_for_fetch" in DBI), bypassing the new and insert calls on the Result class, including any augmentation of these methods provided by components. For example if you are using something like DBIO::UUIDColumns to create primary keys for you, you will find that your PKs are empty. In this case you will have to explicitly force scalar or list context in order to create those values.

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?
Return Value: $new_schema

For each DBIO::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 DBIO::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 DBIO::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 DBIO::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 DBIO::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 overridden by the provided %attrs.

throw_exception

Arguments: $message

Throws an exception. Obeys the exemption rules of DBIO::Carp to report errors from outer-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

Deploys the schema to the current storage. If the storage class provides a native Deploy class (via "dbio_deploy_class" in DBIO::Storage::DBI), uses that. Otherwise throws an exception.

deployment_statements

Arguments: See "deployment_statements" in DBIO::Storage::DBI
Return Value: $listofstatements

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

create_ddl_dir

Arguments: See "create_ddl_dir" in DBIO::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 DBIO 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, $dir) if ($DBIO::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 beyond calling nfreeze, it is just provided here for symmetry.

dclone

Arguments: $object
Return Value: dcloned $object

Recommended way of dcloning DBIO::Row and DBIO::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: $source_name, $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 DBIO::ResultSourceProxy. Equivalent to calling:

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

register_source

Arguments: $source_name, $result_source

This method is called by "register_class".

Registers the DBIO::ResultSource in the schema with the given source name.

unregister_source

Arguments: $source_name

Removes the DBIO::ResultSource from the schema for the given source name.

register_extra_source

Arguments: $source_name, $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.

load_namespaces

Loads result and resultset classes from the configured namespaces and registers them on the schema class.

The complete option semantics are documented in the load_namespaces reference section above.

skill

my $markdown = $schema->skill('mysql-database');

Return the markdown text of the named agent skill (see DBIO::Skills). The leading dbio- is optional. A per-schema override set via the "skills" attribute wins; otherwise the skill is resolved from the bundled sharedirs of the loaded DBIO distributions, including this schema's own driver.

SETUP METHODS

load_namespaces

Arguments: %options?

package MyApp::Schema;
__PACKAGE__->load_namespaces();

__PACKAGE__->load_namespaces(
   result_namespace => 'Res',
   resultset_namespace => 'RSet',
   default_resultset_class => '+MyApp::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 ResultSource instance 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_class', but it seems
that you had already set '$result_class' to use '$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 DBIO 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: DBIO::Storage::DBI

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

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

Most database-specific storage classes now ship in separate DBIO driver distributions (for example DBIO::PostgreSQL::Storage, DBIO::MySQL::Storage, DBIO::SQLite::Storage). If these distributions are installed, DBIO::Storage::DBI will usually autodetect and load the correct storage based on your DSN.

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 DBIO::Replicated::Storage 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 DBIO::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 DBIO's internal execution control flow.

Example:

package My::Schema;
use base qw/DBIO::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{DBIO_TRACE} is true.

sqlt_deploy_hook

Arguments: $sqlt_schema

An optional sub which you can declare in your own Schema class that will get called during deployment of the schema via "deploy".

For an example of what you can do with this, see "Adding Indexes And Functions To Your SQL" in DBIO::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 deployment process before SQL is generated. If you want to execute post-deploy statements which can not be generated automatically, the currently suggested method is to overload "deploy" and use dbh_do.

AUTHOR

DBIO & DBIx::Class Authors

COPYRIGHT AND LICENSE

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

To install DBIO, copy and paste the appropriate command in to your terminal.

cpanm

cpanm DBIO

CPAN shell

perl -MCPAN -e shell
install DBIO

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

VERSION

SYNOPSIS

DESCRIPTION

METHODS

connect

Overloading

resultset

sources

source

class

txn_do

txn_scope_guard

txn_begin

txn_commit

txn_rollback

storage

populate

connection

Overloading

compose_namespace

svp_begin

svp_release

svp_rollback

clone

throw_exception

deploy

deployment_statements

create_ddl_dir

ddl_filename

thaw

freeze

dclone

schema_version

register_class

register_source

unregister_source

register_extra_source

load_namespaces

skill

SETUP METHODS

load_namespaces

Warnings

Examples

load_classes

storage_type

exception_action

stacktrace

sqlt_deploy_hook

AUTHOR

COPYRIGHT AND LICENSE

Module Install Instructions

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