Alzabo::Runtime::Schema - Schema objects
use Alzabo::Runtime::Schema qw(some_schema); my $schema = Alzabo::Runtime::Schema->load_from_file( name => 'foo' ); $schema->set_user( $username ); $schema->set_password( $password ); $schema->connect;
This object can only be loaded from a file. The file is created whenever a corresponding Alzabo::Create::Schema object is saved.
Alzabo::Schema
Loads a schema from a file. This is the only constructor for this class.
name => $schema_name
An Alzabo::Runtime::Schema object.
Alzabo::Runtime::Schema
Alzabo::Exception::Params
The username used by the schema when connecting to the database.
Set the username to use when connecting to the database.
The password used by the schema when connecting to the database.
Set the password to use when connecting to the database.
The host used by the schema when connecting to the database.
Set the host to use when connecting to the database.
A boolean value indicating whether this schema will attempt to maintain referential integrity.
Sets the value returned by the referential_integrity method. If true, then when Alzabo::Runtime::Row objects are deleted, updated, or inserted, they will report this activity to any relevant Alzabo::Runtime::ForeignKey objects for the row, so that the foreign key objects can take appropriate action.
referential_integrity
Alzabo::Runtime::Row
Alzabo::Runtime::ForeignKey
Defaults to false.
Calls the Alzabo::Driver->connect method for the driver owned by the schema. The username, password, and host set for the schema will be passed to the driver, as will any additional parameters given to this method. See the Alzabo::Driver->connect method for more details.
Alzabo::Driver->connect
Joins are done by taking the tables provided in order, and finding a relation between them. If any given table pair has more than one relation, then this method will fail. The relations, along with the values given in the optional where clause will then be used to generate the necessary SQL. See Alzabo::Runtime::JoinCursor for more information.
Alzabo::Runtime::JoinCursor
tables => Alzabo::Runtime::Table object or objects
Alzabo::Runtime::Table
The tables being joined together. The order of these tables is significant if there are more than 2 tables, as we expect to find relationships between tables 1 & 2, 2 & 3, 3 & 4, etc.
This can be either a single table or an array reference of table objects.
select => Alzabo::Runtime::Table object or objects (optional)
This parameter specifies from which tables you would like rows returned. If this parameter is not given, then the tables parameter will be used instead.
where
See the documentation on where clauses for the Alzabo::Runtime::Table class.
order_by
See the documentation on order by clauses for the Alzabo::Runtime::Table class.
limit
See the documentation on limit clauses for the Alzabo::Runtime::Table class.
If the select parameter (or tables parameter) specified that more than one table is desired, then this method will return an Alzabo::Runtime::JoinCursor object representing the results of the join. Otherwise, the method returns an Alzabo::Runtime::RowCursor object.
select
tables
Alzabo::Runtime::RowCursor
Joins are done by taking the tables provided, in order, and finding a relation between them, excluding the last table given. If any given table pair has more than one relation, then this method will fail. The relations, along with the values given in the optional where clause will then be used to generate the necessary SQL. See Alzabo::Runtime::JoinCursor for more information.
The tables being joined together. The order of these tables is significant if there are more than 2 tables, as we expect to find relationships between tables 1 & 2, 2 & 3, 3 & 4, etc. The first and last tables are the ones which are joined together using an outer join.
For example, given the tables 'foo', 'bar', 'baz', and 'quux', in that order, we could read this as follows. Join 'foo', 'bar', and 'baz', then do a left join between 'foo' and 'quux'.
An Alzabo::Runtime::OuterJoinCursor object. representing the results of the join.
Alzabo::Runtime::OuterJoinCursor
This information is never saved to disk. This means that if you're operating in an environment where the schema object is reloaded from disk every time it is used, such as a CGI program spanning multiple requests, then you will have to make a new connection every time. In a persistent evironment, this is not a problem. In a mod_perl environment, you could load the schema and call the set_user and set_password methods in the server startup file. Then all the mod_perl children will inherit the schema with the user and password already set. Otherwise you will have to provide it for each request.
set_user
set_password
You may ask why you have to go to all this trouble to deal with the user and password information. The basic reason was that I did not feel I could come up with a solution to this problem that was secure, easy to configure and use, and cross-platform compatible. Rather, I think it is best to let each user decide on a security practice with which they feel comfortable. If anybody does come up with such a scheme, then code submissions are more than welcome.
If Alzabo is attempting to maintain referential integrity and you are not using either the Alzabo::ObjectCache or Alzabo::ObjectCacheIPC module, then situations can arise where objects you are holding onto in memory can get out of sync with the database and you will not know this. If you are using one of the cache modules then attempts to access data from an expired or deleted object will throw an exception, allowing you to try again (if it is expired) or give up (if it is deleted). Please see Alzabo::ObjectCache for more details.
Alzabo::ObjectCache
Alzabo::ObjectCacheIPC
Dave Rolsky, <autarch@urth.org>
To install Alzabo, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Alzabo
CPAN shell
perl -MCPAN -e shell install Alzabo
For more information on module installation, please visit the detailed CPAN module installation guide.