NAME

       DBIx::Introspector - Detect what database you are connected to

VERSION

       version 0.001005

SYNOPSIS

        my $d = DBIx::Introspector->new(drivers => '2013-12.01');

        # standard dialects
        $d->decorate_driver_unconnected(Pg     => concat_sql => '? || ?');
        $d->decorate_driver_unconnected(SQLite => concat_sql => '? || ?');

        # non-standard
        $d->decorate_driver_unconnected(MSSQL  => concat_sql => '? + ?');
        $d->decorate_driver_unconnected(mysql  => concat_sql => 'CONCAT( ?, ? )');

        my $concat_sql = $d->get($dbh, $dsn, 'concat_sql');

DESCRIPTION

       "DBIx::Introspector" is a module factored out of the DBIx::Class database detection code.
       Most code that needs to detect which database it is connected to assumes that there is a
       one-to-one mapping from database drivers to database engines.  Unfortunately reality is
       rarely that simple.  For instance, DBD::ODBC is typically used to connect to SQL Server,
       but ODBC can be used to connect to PostgreSQL, MySQL, and Oracle.  Additionally, while
       ODBC is the most common way to connect to SQL Server, it is not the only option, as
       DBD::ADO can also be used.

       "DBIx::Introspector" can correctly detect which database you are connected to, because it
       was factored out of a complex, working codebase.  On top of that it has been written to be
       very extensible.  So if you needed to detect which version of your given database you are
       connected to that would not be difficult.

       Furthermore, "DBIx::Introspector" does its best to try to detect information based on the
       dsn you give it if you have not yet connected, so you can possibly avoid connection or at
       least defer connection.

METHODS

   "add_driver"
        $dbii->add_driver({
          name => 'Pg',
          parents => ['DBI'],
          unconnected_options => {
             concat_sql => '? || ?',
             random_func => 'RANDOM()',
          })

       Takes a hashref defining a new driver .

   "replace_driver"
        $dbii->replace_driver({
          name => 'Pg',
          parents => ['DBI'],
          unconnected_options => {
             concat_sql => '? || ?',
             random_func => 'RANDOM()',
          })

       Takes a hashref replacing an existing driver .  Replaces the driver already defined with
       the same name.

   "decorate_driver_connected"
        $dbii->decorate_driver_connected('MSSQL', 'concat_sql', '? + ?')

       Takes a "driver name", "key" and a "value".  The "key value" pair will be inserted into
       the driver's "connected_options".

   "decorate_driver_unconnected"
        $dbii->decorate_driver_unconnected('SQLite', 'concat_sql', '? || ?')

       Takes a "driver name", "key" and a "value".  The "key value" pair will be inserted into
       the driver's "unconnected_options".

   "get"
        $dbii->get($dbh, $dsn, 'concat_sql')

       Takes a "dbh", "dsn", "key", and optionally a hashref of "options".

       The "dbh" can be a coderef returning a "dbh".  If you provide the "dbh_fallback_connect"
       option it will be used to connect the "dbh" if it is not already connected and then
       queried, if the "dsn" was insufficient.

       So for example, one might do:

        my $dbh;
        $dbii->get(sub { $dbh }, $dsn, 'concat_sql', {
           dbh_fallback_connect => sub { $dbh = DBI->connect($dsn, $user, $pass) },
        });

       Which will only connect if it has to, like if the user is using the "DBD::ODBC" driver to
       connect.

ATTRIBUTES

   "drivers"
       This has no default and is required, though a sane defaultish value does exist.

       Currently there is one predefined set of drivers, named "2013-12.01".  If drivers or facts
       or just the general structure of drivers changes they will always be as a new named set of
       drivers.  "2013-12.01" matches the 0.08250 release of DBIx::Class and probably many
       previous and following releases.

       If you need to define it from scratch, you can just pass an arrayref of drivers; see the
       "DRIVER DEFINITION" section on what is required for that.  But generally it will look
       something like this (from the tests):

        my $d = DBIx::Introspector->new(
          drivers => [ map DBIx::Introspector::Driver->new($_),
             {
                name => 'DBI',
                connected_determination_strategy => sub { $_[1]->{Driver}{Name} },
                unconnected_determination_strategy => sub {
                   my $dsn = $_[1] || $ENV{DBI_DSN} || '';
                   my ($driver) = $dsn =~ /dbi:([^:]+):/i;
                   $driver ||= $ENV{DBI_DRIVER};
                   return $driver
                },
             },
             {
                name => 'SQLite',
                parents => ['DBI'],
                connected_determination_strategy => sub {
                   my ($v) = $_[1]->selectrow_array('SELECT "value" FROM "a"');
                   return "SQLite$v"
                },
                connected_options => {
                   bar => sub { 2 },
                },
                unconnected_options => {
                   borg => sub { 'magic ham' },
                },
             },
             { name => 'SQLite1', parents => ['SQLite'] },
             { name => 'SQLite2', parents => ['SQLite'] },
          ]
        );

DRIVER DEFINITION

       Drivers ("DBIx::Introspector::Driver" objects) have the following six attributes:

   "name"
       Required.  Must be unique among the drivers contained in the introspector.

   "parents"
       Arrayref of parent drivers.  This allows parent drivers to implement common options among
       children.  So for example on might define a driver for each version of PostgreSQL, and
       have a parent driver that they all use for common base info.

   "connected_determination_strategy"
       This is a code reference that is called as a method on the driver with the "dbh" as the
       first argument and an optional "dsn" as the second argument.  It should return a driver
       name.

   "unconnected_determination_strategy"
       This is a code reference that is called as a method on the driver with the "dsn" as the
       first argument.  It should return a driver name.

   "connected_options"
       Hashref of "key value" pairs for detecting information based on the "dbh".  A value that
       is not a code reference is returned directly, though I suggest non-coderefs all go in the
       "unconnected_options" so that they may be used without connecting if possilbe.

       If a code reference is passed it will get called as a method on the driver with the
       following list of values:

       "dbh"
         This is the connected "dbh" that you can use to introspect the database.

       "dsn"
         This is the "dsn" passed to "get", possibly undefined.

   "unconnected_options"
       Hashref of "key value" pairs for detecting information based on the "dsn".  A value that
       is not a code reference is returned directly.

       If a code reference is passed it will get called as a method on the driver with the
       following list value:

       "dsn"
         This is the connected "dsn" that you can use to introspect the database.

AUTHOR

       Arthur Axel "fREW" Schmidt <frioux+cpan@gmail.com>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2015 by Arthur Axel "fREW" Schmidt.

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