libalzabo-perl 0.92-3 / usr / share / perl5 / Alzabo / QuickRef.pod

=head1 NAME

Alzabo::QuickRef - A quick reference to methods in the Alzabo classes

=head1 GENERAL

This reference is intended to provide a quick reference to I<some> of
the more commonly used methods that Alzabo provides.  In addition,
this reference can give you an idea of what classes contain certain
I<types> of methods, so you have an idea of where to look in order to
figure out how to achieve a certain task.

=head2 Alzabo, Alzabo::Create, and Alzabo::Runtime

These modules are mostly used just to load other modules.  The
C<Alzabo::Runtime> module can be used to preload schemas at compile
time by doing:

  use Alzabo::Runtime qw( schema1 schema2 schema3 );

=head2 Alzabo::MethodMaker

This module can be used to generate many useful convenience methods.
This is done by auto-generating methods in new packages and
re-blessing some of the schema objects into these packages.  To have
it generate all the possible methods for a schema you would do:

  use Alzabo::MethodMaker ( schema => 'some_schema',
                            # Root for new packages
                            class_root => 'My::Data',
                            # Make all possible methods
                            all => 1 );

This will make convenience methods for such things as getting table
and column objects, following various types of foreign keys, and
getting data from row objects.

=head1 METHODS

=head2 Retrieving data

=head3 Alzabo::Runtime::Schema

This object allows you to connect to the database.  It contains
several data retrieval methods including
L<C<join>|Alzabo::QuickRef/join>.

=over 4

=item * load_from_file

=for html_docs type=class

Load an existing schema object from disk.  Returns a new schema
object.

=for html_docs link=L<More|Alzabo::Create::Schema/load_from_file($name)>

=item * set_user ($user)

=for html_docs type=object

Set the username to be used when connecting to the database.

=for html_docs link=L<More|Alzabo::Runtime::Schema/set_user ($user)>

=item * set_password ($password)

=for html_docs type=object

Set the password to be used when connecting to the database.

=for html_docs link=L<More|Alzabo::Runtime::Schema/set_password ($password)>

=item * set_host ($host)

=for html_docs type=object

Set the host to be used when connecting to the database.

=for html_docs link=L<More|Alzabo::Runtime::Schema/set_host ($host)>

=item * connect (%params)

=for html_docs type=object

Connect to the RDBMS.  This will use the previously set
username/password/host, though these can be overridden by the
C<%params> given to the call.

B<Important>: This method must be called before any data retrieval is
attempted.

=for html_docs link=L<More|Alzabo::Runtime::Schema/connect (%params)>

=item * join

=for html_docs type=object

Fetch rows from one or more tables based on a table join.  Returns
either a L<C<Alzabo::Runtime::RowCursor>|Alzabo::Runtime::RowCursor>
or L<C<Alzabo::Runtime::JoinCursor>|Alzabo::Runtime::JoinCursor>
object.

=for html_docs link=L<More|Alzabo::Runtime::Schema/join>

=item * function/select

=for html_docs type=object

Allows you to execute arbitrary column aggregate SQL functions such as
C<AVG> or C<MAX> with a multi-table join.

=for html_docs link=L<More|Alzabo::Runtime::Schema/function and select>

=item * table ($name)

=for html_docs type=object

Returns an L<C<Alzabo::Runtime::Table>|Alzabo::Runtime::Table> object.
This is important because most of the row fetching operations are
table object methods.

=for html_docs link=L<More|Alzabo::Runtime::Schema/table ($name)>

=back

=head3 Alzabo::Runtime::Table

Objects in this class have methods allowing you to insert new rows as
well as retrieving exist data in the form of
L<C<Alzabo::Runtime::Row>|Alzabo::Runtime::Row> or
L<C<Alzabo::Runtime::RowCursor>|Alzabo::Runtime::RowCursor> objects.

All methods that return a single row return an
L<C<Alzabo::Runtime::Row>|Alzabo::Runtime::Row> object.

All methods that return multiple rows return an
L<C<Alzabo::Runtime::RowCursor>|Alzabo::Runtime::RowCursor> object.

All methods that return rows can be given the C<no_cache> parameter,
which ensures that the row(s) returned will not be cached.  Rows
obtained in this manner should not be updated or deleted, as this will
play havoc with the caching system.  See the
L<C<Alzabo::Runtime::Row>|Alzabo::Runtime::Row> documentation for more
details.

All methods that return multiple rows in the form of a cursor object
can take an C<order_by> parameter.  See the
L<C<Alzabo::Runtime::Table>|Alzabo::Runtime::Table> documentation for
more details.

=over 4

=item * insert

=for html_docs type=object

Insert a new row and return it.

=for html_docs link=L<More|Alzabo::Runtime::Table/insert>

=item * row_by_pk

=for html_docs type=object

Returns the row identified by the primary key give.

=for html_docs link=L<More|Alzabo::Runtime::Table/row_by_pk>

=item * rows_where

=for html_docs type=object

Retrieves a set of rows based on a where clause.  Please see the
method documentation for details on how where clauses are constructed.

=for html_docs link=L<More|Alzabo::Runtime::Table/rows_where>

=item * all_rows

=for html_docs type=object

Retrieves all the rows in the table.

=for html_docs link=L<More|Alzabo::Runtime::Table/all_rows>

=item * function/select

=for html_docs type=object

Allows you to execute arbitrary column aggregate SQL functions such as
C<AVG> or C<MAX>.

=for html_docs link=L<More|Alzabo::Runtime::Table/function and select>

=item * potential_row

=for html_docs type=object

Make a new L<C<Alzabo::Runtime::Row>|Alzabo::Runtime::Row> in the
"potential" state.

=for html_docs link=L<More|Alzabo::Runtime::Table/potential_row>

=back

=head3 Alzabo::Runtime::Row

Objects in this class represent a single row of data.  You can
retrieve the actual column values from it, update it, or delete it.

=over 4

=item * select (@list_of_column_names)

=for html_docs type=object

Given a list of column names, this method returns the values for those
columns.

=for html_docs link=L<More|Alzabo::Runtime::Row/select (@list_of_column_names)>

=item * update (%hash_of_columns_and_values)

=for html_docs type=object

Given a hash of columns and values, this method will update the
database and the object to match those values.

=for html_docs link=L<More|Alzabo::Runtime::Row/update (%hash_of_columns_and_values)>

=item * delete

=for html_docs type=object

Deletes the row from the database.  Further attempts to retrieve data
from this row will throw an exception.

=for html_docs link=L<More|Alzabo::Runtime::Row/delete>

=item * rows_by_foreign_key

=for html_docs type=object

Given a foreign key object from the row's table to another table,
returns either an L<C<Alzabo::Runtime::Row>|Alzabo::Runtime::Row>
object or an
L<C<Alzabo::Runtime::RowCursor>|Alzabo::Runtime::RowCursor> object for
the row(s) in the table to which the relationship exists, based on the
value of the relevant column(s) in the current row.

This method can also take a C<no_cache> and/or C<order_by> parameter.

=for html_docs link=L<More|Alzabo::Runtime::Row/rows_by_foreign_key>

=back

=head3 Alzabo::Runtime::RowCursor

Objects in this class are used to return multiple rows as a cursor,
rather than as a list.  This is much more efficient, at the expense of
a few extra lines in your code.

=over 4

=item * next

=for html_docs type=object

Returns the next L<C<Alzabo::Runtime::Row>|Alzabo::Runtime::Row>
object, or undef if there are no more.

=for html_docs link=L<More|Alzabo::Runtime::RowCursor/next>

=item * all_rows

=for html_docs type=object

Returns a list of all the remaining
L<C<Alzabo::Runtime::Row>|Alzabo::Runtime::Row> objects, or an empty
list if there are no more.

=for html_docs link=L<More|Alzabo::Runtime::RowCursor/all_rows>

=back

=head2 Creating/removing a schema

=head3 Alzabo::Create::Schema

This object represents a schema, and contains one or more table
objects.  It is only used when creating or altering a schema, as
opposed to when fetching data.  Data manipulation is done via the
C<Alzabo::Runtime::*> classes.

=over 4

=item * reverse_engineer

=for html_docs type=class

Connect to a database and reverse engineer a schema.  Returns a new
schema object.

=for html_docs link=L<More|Alzabo::Create::Schema/reverse_engineer>

=item * load_from_file

=for html_docs type=class

Load an existing schema object from disk.  Returns a new schema
object.

=for html_docs link=L<More|Alzabo::Create::Schema/load_from_file($name)>

=item * create

=for html_docs type=object

If the schema has not yet been instantiated in an RDBMS, this method
will instantiate the schema.  If it has been previously instantiated,
it will bring the schema in the RDBMS into sync with its object
representation (altering tables/columns, etc.)  Where possible, exist
data will be preserved.

=for html_docs link=L<More|Alzabo::Create::Schema/create>

=item * make_sql

=for html_docs type=object

Returns an array, each element of which is a SQL statement.  The SQL
is either the SQL to create the schema from scratch or the SQL needed
to update the RDBMS to match the current object.  See the
L<C<create>|Alzabo::QuickRef/create> method for more details.

=for html_docs link=L<More|Alzabo::Create::Schema/make_sql>

=item * drop

=for html_docs type=object

Drop the database from the RDBMS where it was created.  Does not
remove the schema object itself from disk.

=for html_docs link=L<More|Alzabo::Create::Schema/drop>

=item * delete

=for html_docs type=object

Delete the schema object files from disk.  Does not drop the database
from the RDBMS.

=for html_docs link=L<More|Alzabo::Create::Schema/delete>

=back

=head1 AUTHOR

Dave Rolsky, E<lt>autarch@urth.orgE<gt>

=cut