NAME¶
CGI::Application::Plugin::DBH - Easy DBI access from CGI::Application
VERSION¶
version 4.04
SYNOPSIS¶
use CGI::Application::Plugin::DBH (qw/dbh_config dbh/);
sub cgiapp_init {
my $self = shift;
# use the same args as DBI->connect();
$self->dbh_config($data_source, $username, $auth, \%attr);
# or to use more than one dbh
$self->dbh_config('my_handle',
[ $data_source, $user, $auth, \%attr ]);
$self->dbh_config('my_other_handle',
[ $data_source, $user, $auth, \%attr ]);
}
sub my_run_mode {
my $self = shift;
my $date = $self->dbh->selectrow_array("SELECT CURRENT_DATE");
# again with a named handle
$date = $self->dbh('my_handle')->selectrow_array("SELECT CURRENT_DATE");
# OR ...
my $dbh = $self->dbh;
# again with a named handle
$dbh = $self->dbh('my_other_handle');
my $date = $dbh->selectrow_array("SELECT CURRENT_DATE");
}
DESCRIPTION¶
CGI::Application::Plugin::DBH adds easy access to a DBI database handle to your
CGI::Application modules. Lazy loading is used to prevent a database
connection from being made if the "dbh" method is not called during
the request. In other words, the database connection is not created until it
is actually needed.
METHODS¶
dbh()¶
my $date = $self->dbh->selectrow_array("SELECT CURRENT_DATE");
# again with a named handle
$date = $self->dbh('my_handle')->selectrow_array("SELECT CURRENT_DATE");
# OR ...
my $dbh = $self->dbh;
# again with a named handle
$dbh = $self->dbh('my_other_handle');
my $date = $dbh->selectrow_array("SELECT CURRENT_DATE");
This method will return the current DBI database handle. The database handle is
created on the first call to this method, and any subsequent calls will return
the same handle.
dbh_config()¶
sub cgiapp_init {
my $self = shift;
# use the same args as DBI->connect();
$self->dbh_config($data_source, $username, $auth, \%attr);
# or to use more than one dbh
$self->dbh_config('my_handle',
[ $data_source, $user, $auth, \%attr ]);
$self->dbh_config('my_other_handle',
[ $data_source, $user, $auth, \%attr ]);
# ...or use some existing handle you have
$self->dbh_config($DBH);
$self->dbh_config('my_handle', $DBH); # this works too
# Use a callback to create your owh handle that is still lazy loaded
$self->dbh_config(sub { DBI->connect_cached(); });
}
Used to provide your DBI connection parameters. You can either pass in an
existing DBI database handle, or provide the usual parameters used for
DBI->
connect().
The recommended place to call "dbh_config" is in the
"cgiapp_init" stage of CGI::Application. If this method is called
after the database handle has already been accessed, then it will die with an
error message.
Automatic configuration using CGI::App instance parameters
An alternative to explicitly calling "dbh_config" in your application
is to rely on the presence of specific instance parameters that allow the
plugin to configure itself.
If you set the CGI::App parameter "::Plugin::DBH::dbh_config" to an
array reference the contents of that array will be used as parameters to
"dbh_config" (if it has not been explicitly called before).
The code in the synopsis can be rewritten as
use CGI::Application::Plugin::DBH (qw/dbh/);
# no longer a need to import dbh_config
sub cgiapp_init {
# you do not need to do anything here
}
sub my_run_mode {
# this part stays unchanged
....
}
and in the instance script ( or instance configuration file, if you have)
$app->param('::Plugin::DBH::dbh_config' =>
[ $data_source, $username, $auth, \%attr ] );
If you want to configure more than one handle, set up a hash with the handle
names as keys:
$app->param('::Plugin::DBH::dbh_config' =>
{ my_handle => [ $data_source, $username, $auth, \%attr ] ,
my_other_handle => [ $data_source, $username, $auth, \%attr ]
} );
Automatic configuration with DBI environment variables
If you do not set any parameters, and do not call "dbh_config", this
plugin checks to see if you set the DBI environment variable
"DBI_DSN". If present, this DSN will be used for the default handle.
Note that the DBI documentation does not encourage using this method
(especially in the context of web applications), that you will most likely
have to also set "DBI_USER" and "DBI_PASS", and that this
can only be used for the default handle.
dbh_default_name()¶
sub my_runmode {
my $self = shift;
my $old_handle_name = $self->dbh_default_name('my_handle');
$self->some_legacy_code(); # some_legacy_code() will get "my_handle"
# when it calls $self->dbh() without parameters
$self->dbh_default_name($old_handle_name); # Return to normal.
}
Can be used to alter the name of the handle that is returned by
dbh()
when called with no parameters. It can even be used to alter the name used for
the unnamed handle if called before
dbh_config().
Using this method is completely optional. If you don't have a use for it don't
use it. Internally the handle name "__cgi_application_plugin_dbh" is
used to keep track of the unnamed handle unless it is changed by
dbh_default_name() before a call to
dbh_config() without a name
parameter.
SEE ALSO¶
Ima::DBI is similar, but has much more complexity and features.
CGI::Application, DBI, CGI::Application::Plugin::ValidateRM
AUTHOR¶
Mark Stosberg <mark@stosberg.com>
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2013 by Mark Stosberg.
This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.