Peter Lavender > Padre > Padre::DB

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NAME ^

Padre::DB - An ORLite-based ORM Database API

SYNOPSIS ^

TO BE COMPLETED

DESCRIPTION ^

This module implements access to the database that Padre is using to store bits & pieces. It is using ORLite underneath, for an easy table scheme discovery at runtime. See below to learn about how to update the database scheme.

Updating database scheme

The database is created at runtime if it does not exist, but we are relying on Padre::DB::Migrate. To summarize Padre::DB::Migrate:

Therefore, in order to update the database, you need to do the following:

Congratulations! The database has been updated, and will be updated automatically when users will run the new Padre version...

Accessing and using the database

Now that the database has been updated, you can start using it. Each new table will have a Padre::DB::YourTable module created automatically at runtime by ORLite, providing you with the standard methods described below (see METHODS).

Note: we prefer using underscore for table names instead of camel case. ORLite is smart enough to convert underscore names to camel case module names.

But what if you want to provide some particular methods? For example, one can imagine that if you create a table accessed_files retaining the path and the opening timestamp, you want to create a method most_recent() that will return the last opened file.

In that case, that's quite easy, too:

METHODS ^

Those methods are automatically created for each of the tables (see above). Note that the modules automatically created provide both class methods and instance methods, where the object instances each represent a table record.

dsn

  my $string = Padre::DB->dsn;

The dsn accessor returns the DBI connection string used to connect to the SQLite database as a string.

dbh

  my $handle = Padre::DB->dbh;

To reliably prevent potential SQLite deadlocks resulting from multiple connections in a single process, each ORLite package will only ever maintain a single connection to the database.

During a transaction, this will be the same (cached) database handle.

Although in most situations you should not need a direct DBI connection handle, the dbh method provides a method for getting a direct connection in a way that is compatible with connection management in ORLite.

Please note that these connections should be short-lived, you should never hold onto a connection beyond your immediate scope.

The transaction system in ORLite is specifically designed so that code using the database should never have to know whether or not it is in a transation.

Because of this, you should never call the ->disconnect method on the database handles yourself, as the handle may be that of a currently running transaction.

Further, you should do your own transaction management on a handle provided by the <dbh> method.

In cases where there are extreme needs, and you absolutely have to violate these connection handling rules, you should create your own completely manual DBI->connect call to the database, using the connect string provided by the dsn method.

The dbh method returns a DBI::db object, or throws an exception on error.

begin

  Padre::DB->begin;

The begin method indicates the start of a transaction.

In the same way that ORLite allows only a single connection, likewise it allows only a single application-wide transaction.

No indication is given as to whether you are currently in a transaction or not, all code should be written neutrally so that it works either way or doesn't need to care.

Returns true or throws an exception on error.

commit

  Padre::DB->commit;

The commit method commits the current transaction. If called outside of a current transaction, it is accepted and treated as a null operation.

Once the commit has been completed, the database connection falls back into auto-commit state. If you wish to immediately start another transaction, you will need to issue a separate ->begin call.

Returns true or throws an exception on error.

rollback

The rollback method rolls back the current transaction. If called outside of a current transaction, it is accepted and treated as a null operation.

Once the rollback has been completed, the database connection falls back into auto-commit state. If you wish to immediately start another transaction, you will need to issue a separate ->begin call.

If a transaction exists at END-time as the process exits, it will be automatically rolled back.

Returns true or throws an exception on error.

do

  Padre::DB->do(
      'insert into table ( foo, bar ) values ( ?, ? )', {},
      \$foo_value,
      \$bar_value,
  );

The do method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction.

It takes the same parameters and has the same return values and error behaviour.

selectall_arrayref

The selectall_arrayref method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction.

It takes the same parameters and has the same return values and error behaviour.

selectall_hashref

The selectall_hashref method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction.

It takes the same parameters and has the same return values and error behaviour.

selectcol_arrayref

The selectcol_arrayref method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction.

It takes the same parameters and has the same return values and error behaviour.

selectrow_array

The selectrow_array method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction.

It takes the same parameters and has the same return values and error behaviour.

selectrow_arrayref

The selectrow_arrayref method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction.

It takes the same parameters and has the same return values and error behaviour.

selectrow_hashref

The selectrow_hashref method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction.

It takes the same parameters and has the same return values and error behaviour.

prepare

The prepare method is a direct wrapper around the equivalent DBI method, but applied to the appropriate locally-provided connection or transaction

It takes the same parameters and has the same return values and error behaviour.

In general though, you should try to avoid the use of your own prepared statements if possible, although this is only a recommendation and by no means prohibited.

pragma

  # Get the user_version for the schema
  my $version = Padre::DB->pragma('user_version');

The pragma method provides a convenient method for fetching a pragma for a database. See the SQLite documentation for more details.

SUPPORT ^

Padre::DB is based on ORLite.

Documentation created by ORLite::Pod 0.10.

For general support please see the support section of the main project documentation.

AUTHOR ^

Adam Kennedy <adamk@cpan.org>

COPYRIGHT ^

Copyright 2008-2013 The Padre development team as listed in Padre.pm.

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

The full text of the license can be found in the LICENSE file included with this module.

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