oracular (3) Alzabo::QuickRef.3pm.gz
NAME
Alzabo::QuickRef - A quick reference to methods in the Alzabo classes
GENERAL
This reference is intended to provide a quick reference to some of the more commonly used methods that
Alzabo provides. In addition, this reference can give you an idea of what classes contain certain types
of methods, so you have an idea of where to look in order to figure out how to achieve a certain task.
Alzabo, Alzabo::Create, and Alzabo::Runtime
These modules are mostly used just to load other modules. The "Alzabo::Runtime" module can be used to
preload schemas at compile time by doing:
use Alzabo::Runtime qw( schema1 schema2 schema3 );
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.
METHODS
Retrieving data
Alzabo::Runtime::Schema
This object allows you to connect to the database. It contains several data retrieval methods including
"join".
• load_from_file
Load an existing schema object from disk. Returns a new schema object.
• set_user ($user)
Set the username to be used when connecting to the database.
• set_password ($password)
Set the password to be used when connecting to the database.
• set_host ($host)
Set the host to be used when connecting to the database.
• connect (%params)
Connect to the RDBMS. This will use the previously set username/password/host, though these can be
overridden by the %params given to the call.
Important: This method must be called before any data retrieval is attempted.
• join
Fetch rows from one or more tables based on a table join. Returns either a
"Alzabo::Runtime::RowCursor" or "Alzabo::Runtime::JoinCursor" object.
• function/select
Allows you to execute arbitrary column aggregate SQL functions such as "AVG" or "MAX" with a multi-
table join.
• table ($name)
Returns an "Alzabo::Runtime::Table" object. This is important because most of the row fetching
operations are table object methods.
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 "Alzabo::Runtime::Row" or "Alzabo::Runtime::RowCursor" objects.
All methods that return a single row return an "Alzabo::Runtime::Row" object.
All methods that return multiple rows return an "Alzabo::Runtime::RowCursor" object.
All methods that return rows can be given the "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 "Alzabo::Runtime::Row" documentation for more details.
All methods that return multiple rows in the form of a cursor object can take an "order_by" parameter.
See the "Alzabo::Runtime::Table" documentation for more details.
• insert
Insert a new row and return it.
• row_by_pk
Returns the row identified by the primary key give.
• rows_where
Retrieves a set of rows based on a where clause. Please see the method documentation for details on
how where clauses are constructed.
• all_rows
Retrieves all the rows in the table.
• function/select
Allows you to execute arbitrary column aggregate SQL functions such as "AVG" or "MAX".
• potential_row
Make a new "Alzabo::Runtime::Row" in the "potential" state.
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.
• select (@list_of_column_names)
Given a list of column names, this method returns the values for those columns.
• update (%hash_of_columns_and_values)
Given a hash of columns and values, this method will update the database and the object to match
those values.
• delete
Deletes the row from the database. Further attempts to retrieve data from this row will throw an
exception.
• rows_by_foreign_key
Given a foreign key object from the row's table to another table, returns either an
"Alzabo::Runtime::Row" object or an "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 "no_cache" and/or "order_by" parameter.
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.
• next
Returns the next "Alzabo::Runtime::Row" object, or undef if there are no more.
• all_rows
Returns a list of all the remaining "Alzabo::Runtime::Row" objects, or an empty list if there are no
more.
Creating/removing a schema
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
"Alzabo::Runtime::*" classes.
• reverse_engineer
Connect to a database and reverse engineer a schema. Returns a new schema object.
• load_from_file
Load an existing schema object from disk. Returns a new schema object.
• create
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.
• make_sql
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
"create" method for more details.
• drop
Drop the database from the RDBMS where it was created. Does not remove the schema object itself from
disk.
• delete
Delete the schema object files from disk. Does not drop the database from the RDBMS.
AUTHOR
Dave Rolsky, <autarch@urth.org>