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 overridden 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 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.
- 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.