NAME¶
DBIx::DBSchema::DBD - DBIx::DBSchema Driver Writer's Guide and Base Class
SYNOPSIS¶
perldoc DBIx::DBSchema::DBD
package DBIx::DBSchema::DBD::FooBase
use DBIx::DBSchema::DBD;
@ISA = qw(DBIx::DBSchema::DBD);
DESCRIPTION¶
Drivers should be named DBIx::DBSchema::DBD::DatabaseName, where DatabaseName is
the same as the DBD:: driver for this database. Drivers should implement the
following class methods:
- columns CLASS DBI_DBH TABLE
- Given an active DBI database handle, return a listref of listrefs (see
perllol), each containing six elements: column name, column type,
nullability, column length, column default, and a field reserved for
driver-specific use.
- column CLASS DBI_DBH TABLE COLUMN
- Same as columns above, except return the listref for a single
column. You can inherit from DBIx::DBSchema::DBD to provide this
function.
- primary_key CLASS DBI_DBH TABLE
- Given an active DBI database handle, return the primary key for the
specified table.
- unique CLASS DBI_DBH TABLE
- Deprecated method - see the indices method for new drivers.
Given an active DBI database handle, return a hashref of unique indices. The
keys of the hashref are index names, and the values are arrayrefs which
point a list of column names for each. See "HASHES OF LISTS" in
perldsc and DBIx::DBSchema::Index.
- index CLASS DBI_DBH TABLE
- Deprecated method - see the indices method for new drivers.
Given an active DBI database handle, return a hashref of (non-unique)
indices. The keys of the hashref are index names, and the values are
arrayrefs which point a list of column names for each. See "HASHES OF
LISTS" in perldsc and DBIx::DBSchema::Index.
- indices CLASS DBI_DBH TABLE
- Given an active DBI database handle, return a hashref of all indices, both
unique and non-unique. The keys of the hashref are index names, and the
values are again hashrefs with the following keys:
- name - Index name (redundant)
- using - Optional index method
- unique - Boolean indicating whether or not this is a unique index
- columns - List reference of column names (or expressions)
(See FS::DBIx::DBSchema::Index)
New drivers are advised to implement this method, and existing drivers are
advised to (eventually) provide this method instead of
index and
unique.
For backwards-compatibility with current drivers, the base DBIx::DBSchema::DBD
class provides an
indices method which uses the old
index and
unique methods to provide this data.
- default_db_catalog
- Returns the default database catalog for the DBI table_info command.
Inheriting from DBIx::DBSchema::DBD will provide the default empty
string.
- default_db_schema
- Returns the default database schema for the DBI table_info command.
Inheriting from DBIx::DBSchema::DBD will provide the default empty
string.
- constraints CLASS DBI_DBH TABLE
- Given an active DBI database handle, return the constraints (currently,
foreign keys) for the specified table, as a list of hash references.
Each hash reference has the following keys:
- constraint - contraint name
- columns - List refrence of column names
- table - Foreign taable name
- references - List reference of column names in foreign table
- match -
- on_delete -
- on_update -
- column_callback DBH TABLE_NAME COLUMN_OBJ
- Optional callback for driver-specific overrides to SQL column definitions.
Should return a hash reference, empty for no action, or with one or more of
the following keys defined:
effective_type - Optional type override used during column creation.
explicit_null - Set true to have the column definition declare NULL columns
explicitly
effective_default - Optional default override used during column creation.
effective_local - Optional local override used during column creation.
- add_column_callback DBH TABLE_NAME COLUMN_OBJ
- Optional callback for additional SQL statments to be called when adding
columns to an existing table.
Should return a hash reference, empty for no action, or with one or more of
the following keys defined:
effective_type - Optional type override used during column creation.
effective_null - Optional nullability override used during column creation.
sql_after - Array reference of SQL statements to be executed after the
column is added.
- alter_column_callback DBH TABLE_NAME OLD_COLUMN_OBJ NEW_COLUMN_OBJ
- Optional callback for overriding the SQL statments to be called when
altering columns to an existing table.
Should return a hash reference, empty for no action, or with one or more of
the following keys defined:
sql_alter - Alter SQL statement(s) for changing everything about a column.
Specifying this overrides processing of individual changes (type,
nullability, default, etc.).
sql_alter_type - Alter SQL statement(s) for changing type and length (there
is no default).
sql_alter_null - Alter SQL statement(s) for changing nullability to be used
instead of the default.
- column_value_needs_quoting COLUMN_OBJ
- Optional callback for determining if a column's default value require
quoting. Returns true if it does, false otherwise.
TYPE MAPPING¶
You can define a %typemap array for your driver to map "standard" data
types to database-specific types. For example, the MySQL TIMESTAMP field has
non-standard auto-updating semantics; the MySQL DATETIME type is what other
databases and the ODBC standard call TIMESTAMP, so one of the entries in the
MySQL %typemap is:
'TIMESTAMP' => 'DATETIME',
Another example is the Pg %typemap which maps the standard types BLOB and LONG
VARBINARY to the Pg-specific BYTEA:
'BLOB' => 'BYTEA',
'LONG VARBINARY' => 'BYTEA',
Make sure you use all uppercase-keys.
AUTHOR¶
Ivan Kohler <ivan-dbix-dbschema@420.am>
COPYRIGHT¶
Copyright (c) 2000-2005 Ivan Kohler Copyright (c) 2007-2013 Freeside Internet
Services, Inc. All rights reserved. This program is free software; you can
redistribute it and/or modify it under the same terms as Perl itself.
BUGS¶
SEE ALSO¶
DBIx::DBSchema, DBIx::DBSchema::DBD::mysql, DBIx::DBSchema::DBD::Pg,
DBIx::DBSchema::Index, DBI, DBI::DBD, perllol, "HASHES OF LISTS" in
perldsc