NAME
    DBIx::Class::AuditLog - Simple activity audit logging for DBIx::Class

SYNOPSIS
    Enable the AuditLog schema component in your DBIx::Class::Schema class
    file:

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

        __PACKAGE__->load_components(qw/Schema::AuditLog/);

    Enable the AuditLog component in your the individual DBIx::Class table
    class files that you want to enable logging on:

        package My::Schema::Result::Table
        use base qw/DBIx::Class::Core/;
 
        __PACKAGE__->load_components(qw/AuditLog/);

    In your application wrap any insert/update/delete in a transaction to
    have audit logging activated:

        $my_schema->txn_do(
            sub {
                $my_row->update({ ... });
            }
        );

    Optionally pass an extra hashref to the txn_do method to indicate a user
    and/or a description for the transaction:

        $my_schema->txn_do(
            sub {
                $my_row->update({ ... });
            },
            {
                user => 'username_or_id', # optional
                description => 'description of transaction' # optional
            }
        );

DESCRIPTION
    DBIx::Class::AuditLog is meant for tracking changes made to specific
    tables in your database.

    Any insert/update/delete that requires auditing must be wrapped in a
    "txn_do" statement.

    Transactions are saved as Changesets. Each Changeset can have many
    Actions. An Action can be of type insert/update/delete. Actions can have
    many Changes. Changes show the data that was changed during an action.

    By default all updated columns will be audited in any table where the
    AuditLog component is loaded.

ADDITIONAL DBIC COLUMN ATTRIBUTES
    Individual columns can have additional attributes added to change the
    Audit Log functionality.

  audit_log_column
    On an individual column basis you can disable auditing by setting
    'audit_log_column' to 0:

        __PACKAGE__->add_columns(
          "admin_id",
          { data_type => "integer", is_auto_increment => 1, is_nullable => 0, audit_log_column => 0 },
          "admin_name",
          { data_type => "varchar", is_nullable => 0, size => 20 },
          "admin_pasword",
          { data_type => "varchar", is_nullable => 0, size => 20 },
        );

    If you are using a DBIx::Class generated schema, and don't want to
    modify the column defintions directly, you can add the following to the
    editable portion of the Result Class file:

        __PACKAGE__->add_columns(
            "+admin_id",
            { audit_log_column => 0, }
        );

  force_audit_log_column
    By default, columns are only audited if their value changed. It is
    possible to force auditing on a per-column basis by setting
    'force_audit_log_column' to 1:

        __PACKAGE__->add_columns(
            "+admin_id",
            { force_audit_log_column => 1, }
        );

    If auditing is forced for a column, the 'audit_log_column' attribute is
    ignored.

  modify_audit_value
    It is possible to modify the values stored by DBIC::AuditLog on a
    per-column basis by setting the 'modify_audit_value' attibute to either
    a CodeRef, a method name or any true value. The configured code will be
    run as an object method of the current DBIC::Result object, and expects
    the original value as parameter.

    If 'modify_audit_value' is set to a true value which is NOT a method in
    the current objects class, AuditLog will look for a method called
    'modify_audit_$colname', where $colname is the name of the corresponding
    column.

    Note: AuditLog will simply die if it can not find the modification
    method while 'modify_audit_value' is true.

   EXAMPLES:
    The following examples have the same result:

    *   passing a coderef:

            __PACKAGE__->add_columns(
                "+name",
                { modify_audit_value => sub{
                    my ($self, $value) = @_;
                    $value =~ tr/A-Z/a-z/;
                    return $value;
                }, }
            );

    *   passing a method name:

            __PACKAGE__->add_columns(
                "+name",
                { modify_audit_value => 'to_lowercase'}, 
            );
        
            sub to_lowercase{
                my ($self, $value) = @_;
                $value =~ tr/A-Z/a-z/;
                return $value;
            }

    *   passing a true value which is NOT a method name:

            __PACKAGE__->add_columns(
                "+name",
                { modify_audit_value => 1}, 
            );
        
            sub modify_audit_name{
                my ($self, $value) = @_;
                $value =~ tr/A-Z/a-z/;
                return $value;
            }

TABLE STRUCTURE
    The AuditLog schema is a self-contained schema that keeps no
    relationships to your main schema.

    The AuditLog schema consists of 6 tables:

        +-------------------------+
        | Tables_audit_log_schema |
        +-------------------------+
        | audit_log_action        |
        | audit_log_change        |
        | audit_log_changeset     |
        | audit_log_field         |
        | audit_log_table         |
        | audit_log_user          |
        +-------------------------+

    User
        This table contains a unique list of users that have executed
        transactions. The 'name' field is used to store the User identifier.
        This could be used for a user's name or id or other unique
        identifier as needed.

        This table does not get a relationship to any table in your main
        schema.

            mysql> select * from audit_log_user order by id;
            +----+---------------------+
            | id | name                |
            +----+---------------------+
            |  1 | TestAdminUser       |
            |  2 | YetAnotherAdminUser |
            |  3 | ioncache            |
            |  4 | markj               |
            +----+---------------------+
            4 rows in set (0.01 sec)

    Changeset
        An AuditLogChangeset is an identifier for a transaction. It can have
        many Actions. It can optionally be owned by a User. And optionally
        have a description.

            mysql> select * from audit_log_changeset order by id;
            +----+----------------------------------------------+---------------------+------+
            | id | description                                  | timestamp           | user |
            +----+----------------------------------------------+---------------------+------+
            |  1 | adding new user: JohnSample                  | 2012-06-22 17:16:25 |    1 |
            |  2 | updating username: JaneSample                | 2012-06-22 17:16:25 |    1 |
            |  3 | delete user: JohnSample                      | 2012-06-22 17:16:25 |    2 |
            |  4 | adding new user: TehPwnerer -- no admin user | 2012-06-22 17:16:25 | NULL |
            |  5 | multi-action changeset                       | 2012-06-22 17:16:25 |    3 |
            |  6 | NULL                                         | 2012-06-22 17:16:25 |    4 |
            +----+----------------------------------------------+---------------------+------+
            6 rows in set (0.00 sec)

    Action
        An AuditLogAction is an insert/update/delete belonging to a
        Changeset. It is also owned by Table.

            mysql> select * from audit_log_action order by id;
            +----+-----------+---------------+-------------+--------+
            | id | changeset | audited_table | audited_row | type   |
            +----+-----------+---------------+-------------+--------+
            |  1 |         1 |             1 |           8 | insert |
            |  2 |         2 |             1 |           7 | update |
            |  3 |         3 |             1 |           7 | delete |
            |  4 |         4 |             1 |           9 | insert |
            |  5 |         5 |             1 |          10 | insert |
            |  6 |         5 |             1 |          11 | insert |
            |  7 |         5 |             1 |          11 | update |
            |  8 |         5 |             1 |           9 | update |
            |  9 |         6 |             1 |          13 | insert |
            | 10 |         6 |             1 |          13 | update |
            +----+-----------+---------------+-------------+--------+
            10 rows in set (0.00 sec)

    Change
        An AuditLogChange contains changed data for one AuditLogField in an
        AuditLogAction. The original value is stored in the old_value field
        and the new value is stored in the new_value field.

            mysql> select * from audit_log_change order by id;
            +----+--------+-------+--------------+--------------+
            | id | action | field | old_value    | new_value    |
            +----+--------+-------+--------------+--------------+
            |  1 |      1 |     1 | NULL         | JohnSample   |
            |  2 |      1 |     2 | NULL         | 8            |
            |  3 |      1 |     3 | NULL         | 999-888-7777 |
            |  4 |      3 |     1 | JohnSample   | NULL         |
            |  5 |      3 |     2 | 7            | NULL         |
            |  6 |      3 |     3 | 999-888-7777 | NULL         |
            |  7 |      4 |     1 | NULL         | TehPnwerer   |
            |  8 |      4 |     2 | NULL         | 9            |
            |  9 |      4 |     3 | NULL         | 999-888-7777 |
            | 10 |      5 |     1 | NULL         | Superman     |
            | 11 |      5 |     2 | NULL         | 10           |
            | 12 |      5 |     3 | NULL         | 123-456-7890 |
            | 13 |      6 |     1 | NULL         | Spiderman    |
            | 14 |      6 |     2 | NULL         | 11           |
            | 15 |      6 |     3 | NULL         | 987-654-3210 |
            | 16 |      8 |     1 | TehPnwerer   | TehPwnerer   |
            | 17 |      8 |     3 | 999-888-7777 | 416-123-4567 |
            | 18 |      9 |     1 | NULL         | Drunk Hulk   |
            | 19 |      9 |     2 | NULL         | 13           |
            | 20 |      9 |     3 | NULL         | 123-456-7890 |
            +----+--------+-------+--------------+--------------+
            20 rows in set (0.00 sec)

    AuditedTable
        An AuditLogAuditedTable contains a unique list of tables that are
        being tracked. The name field contains the name of a table from your
        database. AuditLogAuditedTable rows are added as needed whenever an
        insert/update/date occurs.

        Note: at least for DB2, the table name will have the schema name
        added as well, eg., myschema.foo for the foo table in schema
        myschema.

            mysql> select * from audit_log_table order by id;
            +----+------+
            | id | name |
            +----+------+
            |  1 | user |
            +----+------+
            1 row in set (0.00 sec)

    Field
        An AuditLogField contains a unique list of fields for each table
        that is being audited. The name field contains the name of a field
        from a specific table inyour database. AuditLogField rows are added
        as needed whenever an insert/update/date occurs.

            mysql> select * from audit_log_field order by id;
            +----+---------------+-------+
            | id | audited_table | name  |
            +----+---------------+-------+
            |  1 |             1 | name  |
            |  2 |             1 | id    |
            |  3 |             1 | phone |
            +----+---------------+-------+
            3 rows in set (0.00 sec)

DEPLOYMENT
    To deploy an AuditLog schema, load your main schema, and then run the
    deploy command on the audit_log_schema:

        my $schema = AuditTest::Schema->connect( "DBI:mysql:database=audit_test",
            "root", "somepassword", { RaiseError => 1, PrintError => 0 } );
    
        $schema->audit_log_schema->deploy;

    The db user that is deploying the schema must have the correct create
    table permissions.

    Note: this should only be run once.

METHODS
  audit_log_schema
    Returns: DBIC schema

    The Audit Log schema can be accessed from your main schema by calling
    the audit_log_schema method.

        my $al_schema = $schema->audit_log_schema;

  get_changes
    Required: id, table
    Optional: action_type, change_order, field, timestamp
    Returns: DBIC resultset

    A convenience method for reading changes from the Audit Log.

        my $al_schema = $schema->audit_log_schema;
        my $changes = $al_schema->get_changes({
            id           => 1,
            table        => 'foo',
            field        => 'bar',           # optional
            action_type  => 'insert',        # optional, 1 of insert, update, delete
            timestamp    => { '>=', $time }, # optional, $time must be a DateTime object,
            change_order => 'asc',           # optional, 1 of asc, desc
        });

TODO
    *   add auto-deploy of schema if it doesn't exist

    *   add more convenience method(s) for retrieving changes from the Audit
        Log schema

SEE ALSO
    *   DBIx::Class

    *   DBIx::Class::Journal

ACKNOWLEDGEMENTS
    Development time supported by OANDA www.oanda.com
    <http://www.oanda.com>.

    Many ideas and code borrowed from DBIx::Class::Journal.

AUTHOR
    Mark Jubenville (ioncache <mailto:ioncache@gmail.com>)

COPYRIGHT AND LICENCE
    This software is copyright (c) 2012 by Mark Jubenville.

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

