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Alzabo::QuickRef - A quick reference to methods in the Alzabo classes |
Alzabo::QuickRef - A quick reference to methods in the Alzabo classes
The general design of Alzabo is as follows.
There are objects representing the schema, which contains table objects. Table objects contain column, foreign key, and index objects. Column objects contain column definition objects. A single column definition may be shared by multiple columns, but has only one owner.
This is a diagram of these inheritance relationships:
Alzabo::* (::Schema, ::Table, ::Column, ::ColumnDefinition, ::ForeignKey, ::Index)
/ \
is parent to
/ \
Alzabo::Create::* Alzabo::Runtime::*
This a diagram of how objects contain other objects:
Schema - makes--Alzabo::SQLMaker subclass object (many)
/ \
contains contains--Alzabo::Driver subclass object (1)
| \
Table (0 or more) Alzabo::RDBMSRules subclass object (1)
/ \ (* Alzabo::Create::Schema only)
/ \
contains--------------------
/ \ \
/ \ \
ForeignKey Column (0 or more) Index (0 or more)
(0 or more) |
contains
|
ColumnDefinition (1)
Note that more than one column _may_ share a single definition object
(this is explained in the
Alzabo::Create::ColumnDefinition
documentation). This is only relevant if you are writing a schema
creation interface.
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 );
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.
Connect to a database and reverse engineer a schema. Returns a new schema object.
link=LLoad an existing schema object from disk. Returns a new schema object.
link=LIf 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.
link=LReturns 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 the database from the RDBMS where it was created. Does not remove the schema object itself from disk.
link=LDelete the schema object files from disk. Does not drop the database from the RDBMS.
link=L
This object allows you to connect to the database. It contains one
data retrieval, method join.
Load an existing schema object from disk. Returns a new schema object.
link=LSet the username to be used when connecting to the database.
link=LSet the password to be used when connecting to the database.
link=LSet the host to be used when connecting to the database.
link=LConnect 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.
link=LFetch rows from one or more tables based on a table join. Returns
either a Alzabo::Runtime::RowCursor
or Alzabo::Runtime::JoinCursor
object.
Returns an Alzabo::Runtime::Table object.
This is important because most the row fetching operations are part of
that class.
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 a new row and return it.
link=LReturns the row identified by the primary key give.
link=LRetrieves a set of rows based on a where clause. Please see the method documentation for details on how where clauses are constructed.
link=LRetrieves all the rows in the table.
link=LAllows you to execute arbitrary column aggregate SQL functions such as
AVG or MAX.
Objects in this class represent a single row of data. You can retrieve the actual column values from it, update it, or delete it.
Given a list of column names, this method returns the values for those columns.
link=LGiven a hash of columns and values, this method will update the database and the object to match those values.
link=LDeletes the row from the database. Further attempts to retrieve data from this row will throw an exception.
link=LGiven 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.
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.
Returns the next Alzabo::Runtime::Row
object, or undef if there are no more.
Returns a list of all the remaining
Alzabo::Runtime::Row objects, or an empty
list if there are no more.
Dave Rolsky, <autarch@urth.org>
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Alzabo::QuickRef - A quick reference to methods in the Alzabo classes |