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Postgresql Auto logging for DBIx

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README.pod

NAME

DBIx-Class-PgLog

PgSQL Auto Logging for DBIx transactions - inspired from DBIx::Class::AuditLog

The PgLog schema consists of 2 tables LogSet and Log, Log table extensively makes use of the power of Postgres to store the Columns, OldValues and NewValues in an Column Array format to avoid the relational database structure which imporves the performance of write and read from PgLog.

INSTALLATION

To install this module, run the following commands:

        perl Makefile.PL
        make
        make test
        make install

SYNOPSIS

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

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

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

Enable the PgLog 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/PgLog/);

If you want to use methods created by DBIx::Class::Relationship::Base, like "add_to_$rel" or "set_$rel", if you are planing to use "delete" in DBIx::Class::ResultSet or "update" in DBIx::Class::ResultSet or if you use modules which make use of these methods (like HTML::FormHandler or DBIx::Class::ResultSet::RecursiveUpdate, load the PgLog-component in your ResultSet classes:

    package My::Schema::ResultSet::Table;

    use base 'DBIx::Class::ResultSet';

    __PACKAGE__->load_components('ResultSet::PgLog');

    1;

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

* Mandatorily Pass an extra hashref to the txn_do method to indicate a UserId and optional Description for the transaction:

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

DESCRIPTION

DBIx::Class::PgLog is meant for Logging 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 LogSets. Each LogSet can have many Log's with TableAction as INSERT/UPDATE/DELETE.

ADDITIONAL DBIC COLUMN ATTRIBUTES

Individual columns can have additional attributes added to change the Audit Log functionality.

pg_log_column

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

    __PACKAGE__->add_columns(
      "admin_id",
      { data_type => "integer", is_auto_increment => 1, is_nullable => 0, pg_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",
        { pg_log_column => 0, }
    );

modify_pg_log_value

It is possible to modify the values stored by DBIC::PgLog on a per-column basis by setting the 'modify_pg_log_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_pg_log_value' is set to a true value which is NOT a method in the current objects class, PgLog will look for a method called 'modify_pg_log_$colname', where $colname is the name of the corresponding column.

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

The following examples have the same result:

passing a coderef:

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

passing a method name:

    __PACKAGE__->add_columns(
        "+name",
        { modify_pg_log_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_pg_log_value => 1},
    );

    sub modify_pg_log_name{
        my ($self, $value) = @_;
        $value =~ tr/A-Z/a-z/;
        return $value;
    }

TABLE STRUCTURE

The PgLog schema is a self-contained schema that keeps no relationships to your main schema.

The PgLog schema consists of 2 tables LogSet and Log, Log table extensively makes use of the power of Postgres to store the Columns, OldValues and NewValues in an Column Array format to avoid the relational database structure which imporves the performance of write and read from PgLog.

                List of relations
         Schema |  Name  | Type  | Owner  
        --------+--------+-------+--------
         public | LogSet | table | sheeju
         public | Log    | table | sheeju
LogSet

The PgLogLogSet is an identifier for a transaction which has optional Description, mandatory UserId.

        pg_log_test=> \d "LogSet"
                                     Table "public.LogSet"
           Column    |   Type   |                       Modifiers                       
        -------------+----------+-------------------------------------------------------
         Id          | integer  | not null default nextval('"LogSet_Id_seq"'::regclass)
         Epoch       | integer  | not null
         Description | text     | not null
         UserId      | integer  | not null
        Indexes:
            "LogSet_pkey" PRIMARY KEY, btree ("Id")
Log

The PgLogLog table is main table which stores the Table, TableAction, Columns and its Old and New Values for each transaction.

        pg_log_test=> \d "Log";
                                              Table "public.Log"
            Column    |           Type           |                     Modifiers                      
        --------------+--------------------------+----------------------------------------------------
         Id           | integer                  | not null default nextval('"Log_Id_seq"'::regclass)
         LogSetId     | bigint                   | not null
         Epoch        | integer                  | not null
         Table        | character varying(128)   | not null
         TableId      | bigint                   | not null
         TableAction  | tableactiontype          | not null default 'UPDATE'::tableactiontype
         Columns      | character varying(255)[] | 
         OldValues    | text[]                   | 
         NewValues    | text[]                   | 
         UserId       | integer                  | not null
        Indexes:
            "Log_pkey" PRIMARY KEY, btree ("Id")

DEPLOYMENT

To deploy an PgLog schema, load your main schema, and then run the deploy command on the pg_log_schema:

        my $schema = PgLogTestPg::Schema->connect( "DBI:Pg:dbname=pg_log_test",
            "sheeju", "sheeju", { RaiseError => 1, PrintError => 1, 'quote_char' => '"', 'quote_field_names' => '0', 'name_sep' => '.' } ) || die("cant connect");;
        
        $schema->pg_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

pg_log_schema

Returns: DBIC schema

The PgLog schema can be accessed from your main schema by calling the pg_log_schema method.

    my $pl_schema = $schema->pg_log_schema;

SEE ALSO

ACKNOWLEDGEMENTS

Development time supported by Exceleron www.exceleron.com.

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

AUTHOR

Sheeju Alex (sheeju)

LICENSE AND COPYRIGHT

Copyright (C) 2013 Sheeju Alex

This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:

http://www.perlfoundation.org/artistic_license_2_0

Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made by someone other than you, you are nevertheless required to ensure that your Modified Version complies with the requirements of this license.

This license does not grant you the right to use any trademark, service mark, tradename, or logo of the Copyright Holder.

This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed.

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