Documentation change: do not overwrite unchanged schema modules

[dbsrgits/DBIx-Class-Schema-Loader.git] / README

NAME
    DBIx::Class::Schema::Loader - Dynamic definition of a
    DBIx::Class::Schema

SYNOPSIS
      package My::Schema;
      use base qw/DBIx::Class::Schema::Loader/;

      __PACKAGE__->loader_options(
          constraint              => '^foo.*',
          # debug                 => 1,
      );

      # in seperate application code ...

      use My::Schema;

      my $schema1 = My::Schema->connect( $dsn, $user, $password, $attrs);
      # -or-
      my $schema1 = "My::Schema"; $schema1->connection(as above);

DESCRIPTION
    DBIx::Class::Schema::Loader automates the definition of a
    DBIx::Class::Schema by scanning database table definitions and setting
    up the columns, primary keys, and relationships.

    DBIx::Class::Schema::Loader currently supports only the DBI storage
    type. It has explicit support for DBD::Pg, DBD::mysql, DBD::DB2,
    DBD::SQLite, and DBD::Oracle. Other DBI drivers may function to a
    greater or lesser degree with this loader, depending on how much of the
    DBI spec they implement, and how standard their implementation is.

    Patches to make other DBDs work correctly welcome.

    See DBIx::Class::Schema::Loader::DBI::Writing for notes on writing your
    own vendor-specific subclass for an unsupported DBD driver.

    This module requires DBIx::Class 0.07006 or later, and obsoletes the
    older DBIx::Class::Loader.

    This module is designed more to get you up and running quickly against
    an existing database, or to be effective for simple situations, rather
    than to be what you use in the long term for a complex database/project.

    That being said, transitioning your code from a Schema generated by this
    module to one that doesn't use this module should be straightforward and
    painless, so don't shy away from it just for fears of the transition
    down the road.

METHODS
  loader_options
    Example in Synopsis above demonstrates a few common arguments. For
    detailed information on all of the arguments, most of which are only
    useful in fairly complex scenarios, see the
    DBIx::Class::Schema::Loader::Base documentation.

    If you intend to use "loader_options", you must call "loader_options"
    before any connection is made, or embed the "loader_options" in the
    connection information itself as shown below. Setting "loader_options"
    after the connection has already been made is useless.

  connection
    See DBIx::Class::Schema for basic usage.

    If the final argument is a hashref, and it contains a key
    "loader_options", that key will be deleted, and its value will be used
    for the loader options, just as if set via the "loader_options" method
    above.

    The actual auto-loading operation (the heart of this module) will be
    invoked as soon as the connection information is defined.

  clone
    See DBIx::Class::Schema.

  dump_to_dir
    Argument: directory name.

    Calling this as a class method on either DBIx::Class::Schema::Loader or
    any derived schema class will cause all affected schemas to dump manual
    versions of themselves to the named directory when they are loaded. In
    order to be effective, this must be set before defining a connection on
    this schema class or any derived object (as the loading happens as soon
    as both a connection and loader_options are set, and only once per
    class).

    See "dump_directory" in DBIx::Class::Schema::Loader::Base for more
    details on the dumping mechanism.

    This can also be set at module import time via the import option
    "dump_to_dir:/foo/bar" to DBIx::Class::Schema::Loader, where "/foo/bar"
    is the target directory.

    Examples:

        # My::Schema isa DBIx::Class::Schema::Loader, and has connection info
        #   hardcoded in the class itself:
        perl -MDBIx::Class::Schema::Loader=dump_to_dir:/foo/bar -MMy::Schema -e1

        # Same, but no hard-coded connection, so we must provide one:
        perl -MDBIx::Class::Schema::Loader=dump_to_dir:/foo/bar -MMy::Schema -e 'My::Schema->connection("dbi:Pg:dbname=foo", ...)'

        # Or as a class method, as long as you get it done *before* defining a
        #  connection on this schema class or any derived object:
        use My::Schema;
        My::Schema->dump_to_dir('/foo/bar');
        My::Schema->connection(........);

        # Or as a class method on the DBIx::Class::Schema::Loader itself, which affects all
        #   derived schemas
        use My::Schema;
        use My::OtherSchema;
        DBIx::Class::Schema::Loader->dump_to_dir('/foo/bar');
        My::Schema->connection(.......);
        My::OtherSchema->connection(.......);

        # Another alternative to the above:
        use DBIx::Class::Schema::Loader qw| dump_to_dir:/foo/bar |;
        use My::Schema;
        use My::OtherSchema;
        My::Schema->connection(.......);
        My::OtherSchema->connection(.......);

  make_schema_at
    This simple function allows one to create a Loader-based schema
    in-memory on the fly without any on-disk class files of any kind. When
    used with the "dump_directory" option, you can use this to generate a
    rough draft manual schema from a dsn without the intermediate step of
    creating a physical Loader-based schema class.

    The return value is the input class name.

    This function can be exported/imported by the normal means, as
    illustrated in these Examples:

        # Simple example, creates as a new class 'New::Schema::Name' in
        #  memory in the running perl interpreter.
        use DBIx::Class::Schema::Loader qw/ make_schema_at /;
        make_schema_at(
            'New::Schema::Name',
            { debug => 1 },
            [ 'dbi:Pg:dbname="foo"','postgres' ],
        );

        # Complex: dump loaded schema to disk, all from the commandline:
        perl -MDBIx::Class::Schema::Loader=make_schema_at,dump_to_dir:./lib -e 'make_schema_at("New::Schema::Name", { debug => 1 }, [ "dbi:Pg:dbname=foo","postgres" ])'

        # Same, but inside a script, and using a different way to specify the
        # dump directory:
        use DBIx::Class::Schema::Loader qw/ make_schema_at /;
        make_schema_at(
            'New::Schema::Name',
            { debug => 1, dump_directory => './lib' },
            [ 'dbi:Pg:dbname="foo"','postgres' ],
        );

  rescan
    Re-scans the database for newly added tables since the initial load, and
    adds them to the schema at runtime, including relationships, etc. Does
    not process drops or changes.

    Returns a list of the new monikers added.

EXAMPLE
    Using the example in DBIx::Class::Manual::ExampleSchema as a basis
    replace the DB::Main with the following code:

      package DB::Main;

      use base qw/DBIx::Class::Schema::Loader/;

      __PACKAGE__->loader_options(
          debug         => 1,
      );
      __PACKAGE__->connection('dbi:SQLite:example.db');

      1;

    and remove the Main directory tree (optional). Every thing else should
    work the same

KNOWN ISSUES
  Multiple Database Schemas
    Currently the loader is limited to working within a single schema (using
    the database vendors' definition of "schema"). If you have a
    multi-schema database with inter-schema relationships (which is easy to
    do in PostgreSQL or DB2 for instance), you only get to automatically
    load the tables of one schema, and any relationships to tables in other
    schemas will be silently ignored.

    At some point in the future, an intelligent way around this might be
    devised, probably by allowing the "db_schema" option to be an arrayref
    of schemas to load.

    In "normal" DBIx::Class::Schema usage, manually-defined source classes
    and relationships have no problems crossing vendor schemas.

AUTHOR
    Brandon Black, "blblack@gmail.com"

    Based on DBIx::Class::Loader by Sebastian Riedel

    Based upon the work of IKEBE Tomohiro

THANK YOU
    Matt S Trout, all of the #dbix-class folks, and everyone who's ever sent
    in a bug report or suggestion.

LICENSE
    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

SEE ALSO
    DBIx::Class, DBIx::Class::Manual::ExampleSchema