Dancer::Plugin::Database(3pm)				User Contributed Perl Documentation			     Dancer::Plugin::Database(3pm)

NAME

       Dancer::Plugin::Database - easy database connections for Dancer applications

SYNOPSIS

	   use Dancer;
	   use Dancer::Plugin::Database;

	   # Calling the database keyword will get you a connected database handle:
	   get '/widget/view/:id' => sub {
	       my $sth = database->prepare(
		   'select * from widgets where id = ?',
	       );
	       $sth->execute(params->{id});
	       template 'display_widget', { widget => $sth->fetchrow_hashref };
	   };

	   # The handle is a Dancer::Plugin::Database::Handle object, which subclasses
	   # DBI's DBI::db handle and adds a few convenience features, for example:
	   get '/insert/:name' => sub {
	       database->quick_insert('people', { name => params->{name} });
	   };

	   get '/users/:id' => sub {
	       template 'display_user', {
		   person => database->quick_select('users', { id => params->{id} }),
	       };
	   };

	   dance;

       Database connection details are read from your Dancer application config - see below.

DESCRIPTION

       Provides an easy way to obtain a connected DBI database handle by simply calling the database keyword within your Dancer application

       Returns a Dancer::Plugin::Database::Handle object, which is a subclass of DBI's "DBI::db" connection handle object, so it does everything
       you'd expect to do with DBI, but also adds a few convenience methods.  See the documentation for Dancer::Plugin::Database::Handle for full
       details of those.

       Takes care of ensuring that the database handle is still connected and valid.  If the handle was last asked for more than
       "connection_check_threshold" seconds ago, it will check that the connection is still alive, using either the "$dbh->ping" method if the DBD
       driver supports it, or performing a simple no-op query against the database if not.  If the connection has gone away, a new connection will
       be obtained and returned.  This avoids any problems for a long-running script where the connection to the database might go away.

       Care is taken that handles are not shared across processes/threads, so this should be thread-safe with no issues with transactions etc.
       (Thanks to Matt S Trout for pointing out the previous lack of thread safety.  Inspiration was drawn from DBIx::Connector.)

CONFIGURATION

       Connection details will be taken from your Dancer application config file, and should be specified as, for example:

	   plugins:
	       Database:
		   driver: 'mysql'
		   database: 'test'
		   host: 'localhost'
		   port: 3306
		   username: 'myusername'
		   password: 'mypassword'
		   connection_check_threshold: 10
		   dbi_params:
		       RaiseError: 1
		       AutoCommit: 1
		   on_connect_do: ["SET NAMES 'utf8'", "SET CHARACTER SET 'utf8'" ]
		   log_queries: 1
		   handle_class: 'My::Super::Sexy::Database::Handle'

       The "connection_check_threshold" setting is optional, if not provided, it will default to 30 seconds.  If the database keyword was last
       called more than this number of seconds ago, a quick check will be performed to ensure that we still have a connection to the database, and
       will reconnect if not.  This handles cases where the database handle hasn't been used for a while and the underlying connection has gone
       away.

       The "dbi_params" setting is also optional, and if specified, should be settings which can be passed to "DBI->connect" as its fourth
       argument; see the DBI documentation for these.

       The optional "on_connect_do" setting is an array of queries which should be performed when a connection is established; if given, each
       query will be performed using "$dbh->do".  (If using MySQL, you might want to use this to set "SQL_MODE" to a suitable value to disable
       MySQL's built-in free data loss 'features', for example:

	 on_connect_do: "SET SQL_MODE='TRADITIONAL'"

       (If you're not familiar with what I mean, I'm talking about the insane default behaviour of "hmm, this bit of data won't fit the column
       you're trying to put it in.. hmm, I know, I'll just munge it to fit, and throw a warning afterwards - it's not like you're relying on me
       to, y'know, store what you ask me to store".  See http://effectivemysql.com/presentation/mysql-idiosyncrasies-that-bite/
       <http://effectivemysql.com/presentation/mysql-idiosyncrasies-that-bite/> for just one illustration.  In hindsight, I wish I'd made a
       sensible "sql_mode" a default setting, but I don't want to change that now.)

       The optional "log_queries" setting enables logging of queries generated by the helper functions "quick_insert" et al in
       Dancer::Plugin::Database::Handle.  If you enable it, generated queries will be logged at 'debug' level.	Be aware that they will contain
       the data you're passing to/from the database, so be careful not to enable this option in production, where you could inadvertently log
       sensitive information.

       If you prefer, you can also supply a pre-crafted DSN using the "dsn" setting; in that case, it will be used as-is, and the
       driver/database/host settings will be ignored.  This may be useful if you're using some DBI driver which requires a peculiar DSN.

       The optional "handle_class" defines your own class into which database handles should be blessed.  This should be a subclass of
       Dancer::Plugin::Database::Handle (or DBI::db directly, if you just want to skip the extra features).

   DEFINING MULTIPLE CONNECTIONS
       If you need to connect to multiple databases, this is easy - just list them in your config under "connections" as shown below:

	   plugins:
	       Database:
		   connections:
		       foo:
			   driver: "SQLite"
			   database: "foo.sqlite"
		       bar:
			   driver: "mysql"
			   host: "localhost"
			   ....

       Then, you can call the "database" keyword with the name of the database connection you want, for example:

	   my $foo_dbh = database('foo');
	   my $bar_dbh = database('bar');

RUNTIME CONFIGURATION

       You can pass a hashref to the "database()" keyword to provide configuration details to override any in the config file at runtime if
       desired, for instance:

	   my $dbh = database({ driver => 'SQLite', database => $filename });

       (Thanks to Alan Haggai for this feature.)

AUTOMATIC UTF-8 SUPPORT
       As of version 1.20, if your application is configured to use UTF-8 (you've defined the "charset" setting in your app config as "UTF-8")
       then support for UTF-8 for the database connection will be enabled, if we know how to do so for the database driver in use.

       If you do not want this behaviour, set "auto_utf8" to a false value when providing the connection details.

GETTING A DATABASE HANDLE

       Calling "database" will return a connected database handle; the first time it is called, the plugin will establish a connection to the
       database, and return a reference to the DBI object.  On subsequent calls, the same DBI connection object will be returned, unless it has
       been found to be no longer usable (the connection has gone away), in which case a fresh connection will be obtained.

       If you have declared named connections as described above in 'DEFINING MULTIPLE CONNECTIONS', then calling the database() keyword with the
       name of the connection as specified in the config file will get you a database handle connected with those details.

       You can also pass a hashref of settings if you wish to provide settings at runtime.

CONVENIENCE FEATURES (quick_select, quick_update, quick_insert, quick_delete)
       The handle returned by the "database" keyword is a Dancer::Plugin::Database::Handle object, which subclasses the "DBI::db" DBI connection
       handle.	This means you can use it just like you'd normally use a DBI handle, but extra convenience methods are provided, as documented in
       the POD for Dancer::Plugin::Database::Handle.

       Examples:

	 # Quickly fetch the (first) row whose ID is 42 as a hashref:
	 my $row = database->quick_select($table_name, { id => 42 });

	 # Fetch all badgers as an array of hashrefs:
	 my @badgers = database->quick_select('animals', { genus => 'Mellivora' });

	 # Update the row where the 'id' column is '42', setting the 'foo' column to
	 # 'Bar':
	 database->quick_update($table_name, { id => 42 }, { foo => 'Bar' });

	 # Insert a new row, using a named connection (see above)
	 database('connectionname')->quick_insert($table_name, { foo => 'Bar' });

	 # Delete the row with id 42:
	 database->quick_delete($table_name, { id => 42 });

	 # Fetch all rows from a table (since version 1.30):
	 database->quick_select($table_name, {});

       There's more extensive documentation on these features in Dancer::Plugin::Database::Handle, including using the "order_by", "limit",
       "columns" options to sort / limit results and include only specific columns.

HOOKS

       This plugin uses Dancer's hooks support to allow you to register code that should execute at given times - for example:

	   hook 'database_connected' => sub {
	       my $dbh = shift;
	       # do something with the new DB handle here
	   };

       Currrently defined hook positions are:

       "database_connected"
	   Called when a new database connection has been established, after performing any "on_connect_do" statements, but before the handle is
	   returned.  Receives the new database handle as a parameter, so that you can do what you need with it.

       "database_connection_lost"
	   Called when the plugin detects that the database connection has gone away.  Receives the no-longer usable handle as a parameter, in
	   case you need to extract some information from it (such as which server it was connected to).

       "database_connection_failed"
	   Called when an attempt to connect to the database fails.  Receives a hashref of connection settings as a parameter, containing the
	   settings the plugin was using to connect (as obtained from the config file).

       "database_error"
	   Called when a database error is raised by "DBI".  Receives two parameters: the error message being returned by DBI, and the database
	   handle in question.

       If you need other hook positions which would be useful to you, please feel free to suggest them!

AUTHOR

       David Precious, "<davidp@preshweb.co.uk>"

CONTRIBUTING

       This module is developed on Github at:

       http://github.com/bigpresh/Dancer-Plugin-Database <http://github.com/bigpresh/Dancer-Plugin-Database>

       Feel free to fork the repo and submit pull requests!  Also, it makes sense to watch the repo <https://github.com/bigpresh/Dancer-Plugin-
       Database/toggle_watch> on GitHub for updates.

       Feedback and bug reports are always appreciated.  Even a quick mail to let me know the module is useful to you would be very nice - it's
       nice to know if code is being actively used.

ACKNOWLEDGEMENTS

       Igor Bujna

       Franck Cuny

       Alan Haggai

       Christian Sanchez

       Michael Stiller

       Martin J Evans

       Carlos Sosa

       Matt S Trout

       Matthew Vickers

       Christian Walde

       Alberto Simo~es

       James Aitken (LoonyPandora)

       Mark Allen (mrallen1)

       Sergiy Borodych (bor)

       Mario Domgoergen (mdom)

       Andrey Inishev (inish777)

       Nick S. Knutov (knutov)

BUGS

       Please report any bugs or feature requests to "bug-dancer-plugin-database at rt.cpan.org", or through the web interface at
       http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Dancer-Plugin-Database <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Dancer-Plugin-
       Database>.  I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

       You can find documentation for this module with the perldoc command.

	   perldoc Dancer::Plugin::Database

       You can also look for information at:

       o   RT: CPAN's request tracker

	   http://rt.cpan.org/NoAuth/Bugs.html?Dist=Dancer-Plugin-Database <http://rt.cpan.org/NoAuth/Bugs.html?Dist=Dancer-Plugin-Database>

       o   AnnoCPAN: Annotated CPAN documentation

	   http://annocpan.org/dist/Dancer-Plugin-Database <http://annocpan.org/dist/Dancer-Plugin-Database>

       o   CPAN Ratings

	   http://cpanratings.perl.org/d/Dancer-Plugin-Database <http://cpanratings.perl.org/d/Dancer-Plugin-Database>

       o   Search CPAN

	   http://search.cpan.org/dist/Dancer-Plugin-Database/ <http://search.cpan.org/dist/Dancer-Plugin-Database/>

       You can find the author on IRC in the channel "#dancer" on <irc.perl.org>.

LICENSE AND COPYRIGHT

       Copyright 2010-12 David Precious.

       This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as
       published by the Free Software Foundation; or the Artistic License.

       See http://dev.perl.org/licenses/ for more information.

SEE ALSO

       Dancer

       DBI

       Dancer::Plugin::SimpleCRUD

perl v5.14.2							    2012-06-28					     Dancer::Plugin::Database(3pm)