# 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).

If you want a querylog but don't want or need the [Plack](http://search.cpan.org/perldoc?Plack) debug panel, you
should take a look at [Plack::Middleware::DBIC::QueryLog](http://search.cpan.org/perldoc?Plack::Middleware::DBIC::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 `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, `<[email protected]>`

# COPYRIGHT & LICENSE

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

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