Flexible change tracking framework for DBIx::Class
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NAME

DBIx::Class::AuditAny - Flexible change tracking framework for DBIx::Class

Coverage Status

SYNOPSIS

my $schema = My::Schema->connect(@connect);

use DBIx::Class::AuditAny;

my $Auditor = DBIx::Class::AuditAny->track(
  schema => $schema, 
  track_all_sources => 1,
  collector_class => 'Collector::AutoDBIC',
  collector_params => {
    sqlite_db => 'db/audit.db',
  }
);

DESCRIPTION

This module provides a generalized way to track changes to DBIC databases. The aim is to provide quick/turn-key options to be able to hit the ground running, while also being highly flexible and customizable with sane APIs.

DBIx::Class::AuditAny wants to be a general framework on top of which other Change Tracking modules for DBIC can be written, while also providing fully fleshed, end-user solutions that can be dropped in and work out-of-the-box.

Background

This module was originally written in 2012 for an internal client project, and the process of getting it released open-source as a stand-alone, general-purpose module was started in 2013. However, I got busy with other projects and wasn't able to complete a CPAN release at that time (mainly due to missing docs and minor loose ends). I finally came back to this project (May 2015) to actually get a release out to CPAN. So, even though the release date is in 2015, the majority of the code is actually several years old (and has been running perfectly in production for several client apps the whole time).

API and Usage

AuditAny uses a different API than typical DBIC components. Instead of loading at the schema/result class level with load_components, AuditAny is used by attaching an "Auditor" to an existing schema object instance:

my $schema = My::Schema->connect(@connect);

my $Auditor = DBIx::Class::AuditAny->track(
  schema => $schema, 
  track_all_sources => 1,
  collector_class => 'Collector::AutoDBIC',
  collector_params => {
    sqlite_db => 'db/audit.db',
  }
);

The rationale of this approach is that change tracking isn't necessarily something that needs to be, or should be, defined as a built-in attribute of the schema class. Additionally, because of the object-based approach, it is possible to attach multiple Auditors to a single schema object with multiple calls to DBIx::Class::AuditAny->track.

DATAPOINTS

As changes occur in the tracked schema, information is collected in the form of datapoints at various stages - or contexts - before being passed to the configured Collector. A datapoint has a globally unique name and code used to calculate its value. Code is called at the stage defined by the context of the datapoint. The available contexts are:

set
base
change
source
column

set (AKA changeset) datapoints are specific to an entire set of changes - insert/ update/delete statements grouped in a transaction. Example changeset datapoints include changeset_ts and other broad items. base datapoints are logically the same as set but only need to be calculated once (instead of with every change set). These include things like schema and schema_ver.

change datapoints apply to a specific insert, update or delete statement, and range from simple items such as action (one of 'insert', 'update' or 'delete') to more exotic and complex items like column_changes_json. source datapoints are logically the same as change, but like base datapoints, only need to be calculated once (per source). These include things like table_name and source (source name).

Finally, column datapoints cover information specific to an individual column, such as column_name, old_value and new_value.

There are a number of built-in datapoints (currently stored in DBIx::Class::AuditAny::Util::BuiltinDatapoints which is likely to change), but custom datapoints can also be defined. The Auditor config defines a specific set of datapoints to be calculated (built-in and/or custom). If no datapoints are specified, the default list is used (currently change_ts, action, source, pri_key_value, column_name, old_value, new_value).

The list of datapoints is specified as an ArrayRef in the config. For example:

datapoints => [qw(action_id column_name new_value)],

Custom Datapoints

Custom datapoints are specified as HashRef configs with 3 parameters:

name

The unique name of the datapoint. Should be all lowercase letters, numbers and underscore and must be different from all other datapoints (across all contexts).

context

The context of the datapoint: base, source, set, change or column.

method

CodeRef to calculate and return the value. The CodeRef is called according to the context, and a different context object is supplied for each context. Each context has its own context object type except base which is supplied the Auditor object itself. See Audit Context Objects below.

Custom datapoints are defined in the datapoint_configs param. After defining a new datapoint config it can then be used like any other datapoint. For example:

datapoints => [qw(action_id column_name new_value client_ip)],
datapoint_configs => [
  {
    name => 'client_ip',
    context => 'set',
    method => sub {
      my $contextObj = shift;
      my $c = some_func(...);
      return $c->req->address; 
    }
  }
]

Datapoint Names

Datapoint names must be unique, which means all the built-in datapoint names are reserved. However, if you really want to use an existing datapoint name, or if you want a built-in datapoint to use a different name, you can rename any datapoints like so:

rename_datapoints => {
  new_value => 'new',
  old_value => 'old',
  column_name => 'column',
},

COLLECTORS

Once the Auditor calculates the configured datapoints it passes them to the configured Collector. There are several built-in Collectors provided, but writing a custom Collector is a trivial matter. All you need to do is write a Moo-compatible class which consumes the DBIx::Class::AuditAny::Role::Collector role and implement a record_changes() method. This method is called with a ChangeSet object supplied as the argument at the end of every database transaction which performs a write operation.

No matter how small or large the transaction, the ChangeSet object provides APIs to a nested structure to be able to access all information regarding what changed during the given transaction. (See AUDIT CONTEXT OBJECTS below).

Supplied Collector Classes

The following built-in collector classes are already provided:

AUDIT CONTEXT OBJECTS

Inspired in part by the Catalyst Context object design, the internal machinery which captures and organizes the change datapoints associated with a modifying transaction is wrapped in a nested structure of 3 kinds of "context" objects:

This provides a clean and straightforward API for which Collector classes are able to identify and act on the data in any manner they want, be it recording to a database, logging to a simple file, or taking any kind of programmatic action. Collectors can really be thought of as a structure for powerful external triggers.

ATTRIBUTES

Note: Documentation of all the individual attrs and methods of this class (shown below) is still TBD. However, most meaningful scenarios involving interacting with these is already covered above, or is covered further down in the Examples.

datapoints

allow_multiple_auditors

auto_include_user_defined_datapoints

build_init_args

calling_action_function

change_context_class

changeset_context_class

collector_class

collector_params

column_context_class

datapoint_configs

default_datapoint_class

disable_datapoints

primary_key_separator

record_empty_changes

rename_datapoints

schema

source_context_class

time_zone

track_actions

track_immutable

track_init_args

tracked_action_functions

tracked_sources

METHODS

get_dt

track

get_datapoint_orig

add_datapoints

all_datapoints

get_context_datapoint_names

get_context_datapoints

local_datapoint_data

track_sources

track_all_sources

init_all_sources

init_sources

start_unless_changeset

start_changeset

finish_changeset

finish_if_changeset

clear_changeset

record_changes

EXAMPLES

simple dedicated audit db

Record all changes into a *separate*, auto-generated and initialized SQLite schema/db with default datapoints (Quickest/simplest usage - SYNOPSIS example):

Uses the Collector DBIx::Class::AuditAny::Collector::AutoDBIC

my $schema = My::Schema->connect(@connect);

use DBIx::Class::AuditAny;

my $Auditor = DBIx::Class::AuditAny->track(
  schema => $schema, 
  track_all_sources => 1,
  collector_class => 'Collector::AutoDBIC',
  collector_params => {
    sqlite_db => 'db/audit.db',
  }
);

recording to the same db

Record all changes - into specified target sources within the *same*/tracked schema - using specific datapoints:

Uses the Collector DBIx::Class::AuditAny::Collector::DBIC

DBIx::Class::AuditAny->track(
  schema => $schema, 
  track_all_sources => 1,
  collector_class => 'Collector::DBIC',
  collector_params => {
    target_source => 'MyChangeSet',      # ChangeSet source name
    change_data_rel => 'changes',        # Change source, via rel within ChangeSet
    column_data_rel => 'change_columns', # ColumnChange source, via rel within Change
  },
  datapoints => [ # predefined/built-in named datapoints:
    (qw(changeset_ts changeset_elapsed)),
    (qw(change_elapsed action source pri_key_value)),
    (qw(column_name old_value new_value)),
  ],
);

coderef collector to a file

Dump raw change data for specific sources (Artist and Album) to a file, ignore immutable flags in the schema/result classes, and allow more than one DBIx::Class::AuditAny Auditor to be attached to the same schema object:

Uses 'collect' sugar param to setup a bare-bones CodeRef Collector (DBIx::Class::AuditAny::Role::Collector)

my $Auditor = DBIx::Class::AuditAny->track(
  schema => $schema, 
  track_sources => [qw(Artist Album)],
  track_immutable => 1,
  allow_multiple_auditors => 1,
  collect => sub {
    my $cntx = shift;      # ChangeSet context object
    require Data::Dumper;
    print $fh Data::Dumper->Dump([$cntx],[qw(changeset)]);
    
    # Do other custom stuff...
  }
);

more customizations

Record all updates (but *not* inserts/deletes) - into specified target sources within the same/tracked schema - using specific datapoints, including user-defined datapoints and built-in datapoints with custom names:

DBIx::Class::AuditAny->track(
  schema => CoolCatalystApp->model('Schema')->schema, 
  track_all_sources => 1,
  track_actions => [qw(update)],
  collector_class => 'Collector::DBIC',
  collector_params => {
    target_source => 'MyChangeSet',      # ChangeSet source name
    change_data_rel => 'changes',        # Change source, via rel within ChangeSet
    column_data_rel => 'change_columns', # ColumnChange source, via rel within Change
  },
  datapoints => [
    (qw(changeset_ts changeset_elapsed)),
    (qw(change_elapsed action_id table_name pri_key_value)),
    (qw(column_name old_value new_value)),
  ],
  datapoint_configs => [
    {
      name => 'client_ip',
      context => 'set',
      method => sub {
        my $c = some_func(...);
        return $c->req->address; 
      }
    },
    {
      name => 'user_id',
      context => 'set',
      method => sub {
        my $c = some_func(...);
        $c->user->id;
      }
    }
  ],
  rename_datapoints => {
    changeset_elapsed => 'total_elapsed',
    change_elapsed => 'elapsed',
    pri_key_value => 'row_key',
    new_value => 'new',
    old_value => 'old',
    column_name => 'column',
  },
);

user-defined collector

Record all changes into a user-defined custom Collector class - using default datapoints:

my $Auditor = DBIx::Class::AuditAny->track(
  schema => $schema, 
  track_all_sources => 1,
  collector_class => '+MyApp::MyCollector',
  collector_params => {
    foo => 'blah',
    anything => $val
  }
);

query the audit db

Access/query the audit db of Collector::DBIC and Collector::AutoDBIC collectors:

my $audit_schema = $Auditor->collector->target_schema;
$audit_schema->resultset('AuditChangeSet')->search({...});

# Print the ddl that auto-generated and deployed with a Collector::AutoDBIC collector:
print $audit_schema->resultset('DeployInfo')->first->deployed_ddl;

more examples

See the unit tests (which are extensive) for more examples.

TODO

  • Enable tracking multi-primary-key sources (code currently disabled)

  • Write more tests

  • Write more documentation

  • Add more built-in datapoints

  • Expand the Collector API to be able to provide datapoint configs

  • Separate set/change/column datapoints into 'pre' and 'post' stages

  • Add mechanism to enable/disable tracking (localizable global?)

  • Switch to use Types::Standard

SIMILAR MODULES

DBIx::Class::Journal

DBIx::Class::Journal was the first DBIC change tracking module released to CPAN. It works, but is inflexible and mandates a single mode of operation, which is not ideal in many ways.

DBIx::Class::AuditLog

DBIx::Class::AuditLog takes a more casual approach than DBIx::Class::Journal, which makes it easier to work with. However, it still forces a narrow and specific manner in which it stores the change history data which doesn't fit all workflows.

AuditAny was designed specifically for flexibility. By separating the Auditor - which captures the change data as it happens - from the Collector, which handles storing the data, all sorts of different styles and manners of formatting and storing the audit data can be achieved. In fact, DBIx::Class::AuditLog could be written using AuditAny, and store the data in exactly the same manner by implementing a custom collector class.

DBIx::Class::Shadow

Shadow is a different animal. It is very sophisticated, and places accuracy above all else, with the idea of being able to do things such as reliably "revive" the previous state of rows, etc. The downside of this is that it is also not flexible, in that it handles the entire change life cycle within its logic. This is different from AuditAny, which is more like a packet capture lib for DBIC (like tcpdump/libpcap is a packet capture lib for networks). Unlike the others, Shadow could not be implemented using AuditAny, because the way it captures the change data is specific and fundamentally different.

Unfortunately, DBIx::Class::Shadow is unfinished and has never been released to CPAN (as of the time of this writing, in May 2015). Its current, unfinished status can be seen in GitHub:

SUPPORT

IRC:

Join #rapidapp on irc.perl.org.

AUTHOR

Henry Van Styn <vanstyn@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2012-2015 by IntelliTree Solutions llc.

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