# NAME

Plack::Middleware::Debug::DBIC::QueryLog - DBIC Query Log and Query Analyzer 

## SYNOPSIS

Adds a debug panel and querylog object for logging [DBIx::Class](http://search.cpan.org/perldoc?DBIx::Class) queries.  Has
support for [Catalyst](http://search.cpan.org/perldoc?Catalyst) via a [Catalyst::TraitFor::Model::DBIC::Schema::QueryLog](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog)
compatible trait, [Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack).

    use Plack::Builder;

    my $app = ...; ## Build your Plack App

    builder {
      enable 'Debug', panels =>['DBIC::QueryLog']; 
      $app;
    };

And in you [Catalyst](http://search.cpan.org/perldoc?Catalyst) application, if you are also using
[Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack)

    package MyApp::Web::Model::Schema;
    use parent 'Catalyst::Model::DBIC::Schema';

	__PACKAGE__->config({
        schema_class => 'MyApp::Schema',
        traits => ['QueryLog::AdoptPlack'],
        ## .. rest of configuration
	});

# DESCRIPTION

[DBIx::Class::QueryLog](http://search.cpan.org/perldoc?DBIx::Class::QueryLog) is a tool in the [DBIx::Class](http://search.cpan.org/perldoc?DBIx::Class) software ecosystem
which benchmarks queries.  It lets you log the SQL that [DBIx::Class](http://search.cpan.org/perldoc?DBIx::Class)
is generating, along with bind variables and timestamps.  You can then pass
the querylog object to an analyzer (such as [DBIx::Class::QueryLog::Analyzer](http://search.cpan.org/perldoc?DBIx::Class::QueryLog::Analyzer))
to generate sorted statistics for all the queries between certain log points.

Query logging in [Catalyst](http://search.cpan.org/perldoc?Catalyst) is supported for [DBIx::Class](http://search.cpan.org/perldoc?DBIx::Class) via a trait for
[Catalyst::Model::DBIC::Schema](http://search.cpan.org/perldoc?Catalyst::Model::DBIC::Schema) called
[Catalyst::TraitFor::Model::DBIC::Schema::QueryLog](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog).  This trait will
log all the SQL used by [DBIx::Class](http://search.cpan.org/perldoc?DBIx::Class) for a given request cycle.  This is very
useful since it can help you identify troublesome or bottlenecking queries.

However, [Catalyst::TraitFor::Model::DBIC::Schema::QueryLog](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog) does not provide
out of the box outputting of your analyzed query logs.  Usually you need to
add a bit of templating work to the bottom of your webpage footer, or dump the
output to the logs.  We'd like to provide a lower ceremony experience.

Additionally, it would be nice if we could provide this functionality for all
[Plack](http://search.cpan.org/perldoc?Plack) based applications, not just [Catalyst](http://search.cpan.org/perldoc?Catalyst).  Ideally we'd play nice with
[Plack::Middleware::Debug](http://search.cpan.org/perldoc?Plack::Middleware::Debug) so that the table of our querylog would appear as
a neat Plack based Debug panel.  This bit of middleware provides that function.

Basically we create a new instance of [DBIx::Class::QueryLog](http://search.cpan.org/perldoc?DBIx::Class::QueryLog) and place it
into `$env->{'plack.middleware.dbic.querylog'}` so that it is accessible by
all applications running inside of [Plack](http://search.cpan.org/perldoc?Plack).  You need to 'tell' your application's
instance of [DBIx::Class](http://search.cpan.org/perldoc?DBIx::Class) to use this `$env` key and make sure you set
[DBIx::Class](http://search.cpan.org/perldoc?DBIx::Class)'s debug object correctly:

    use Plack::Middleware::Debug::DBIC::QueryLog;
    my $querylog = $env->{+Plack::Middleware::Debug::DBIC::QueryLog::PSGI_KEY};
    my $cloned_schema = $schema->clone;
    $cloned_schema->storage->debug(1);
    $cloned_schema->storage->debugobj($querylog);

That way when you view the debug panel, we have SQL to review.

There's an application in '/example' you can review for help.  However, if you
are using [Catalyst](http://search.cpan.org/perldoc?Catalyst) and a modern [Catalyst::Model::DBIC::Schema](http://search.cpan.org/perldoc?Catalyst::Model::DBIC::Schema) you can use
the trait [Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack),
which is compatible with [Catalyst::TraitFor::Model::DBIC::Schema::QueryLog](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog).

See the L</SYNOPSIS> example for more details.

# OPTIONS

This debug panel defines the following options.

## querylog_class

This is the class which is used to build the `querylog` unless one is already
defined.  It defaults to [DBIx::Class::QueryLog](http://search.cpan.org/perldoc?DBIx::Class::QueryLog).  You should probably leave
this alone unless you need to subclass or augment [DBIx::Class::QueryLog](http://search.cpan.org/perldoc?DBIx::Class::QueryLog).

If the class name you pass has not already been included (via `use` or 
`require`) we will automatically try to c<require> it.

## querylog_args

Takes a HashRef which is passed to [DBIx::Class::QueryLog](http://search.cpan.org/perldoc?DBIx::Class::QueryLog) at construction.

# SEE ALSO

[Plack::Middleware::Debug](http://search.cpan.org/perldoc?Plack::Middleware::Debug), [Catalyst::TraitFor::Model::DBIC::Schema::QueryLog](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog),
[Catalyst::Model::DBIC::Schema](http://search.cpan.org/perldoc?Catalyst::Model::DBIC::Schema), [Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack](http://search.cpan.org/perldoc?Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack)

# AUTHOR

John Napiorkowski, `<jjnapiork@cpan.org>`

# COPYRIGHT & LICENSE

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