NAME

Tangram::IntrSet - map Set::Object using a foreign key

SYNOPSIS

use Tangram;

# or
use Tangram::Core;
use Tangram::IntrSet;

$schema = Tangram::Schema->new(

	classes => { Basket => { fields => {

	iset =>
	{
		# long form
		fruits =>
		{
			class => 'Fruit',
			coll => 'basket',
		},

		# or (short form)
		fruits => 'Fruit',
	}

DESCRIPTION

This class maps references to Set::Object collections in an intrusive fashion. The persistent fields are grouped in a hash under the iset key in the field hash.

The set may contain only objects of persistent classes. These classes must have a common persistent base class.

Tangram uses a column on the element's table to store the id of the object containing the collection.

CAUTION: the same object may not be an element of the same collection, in two different objects. This mapping may be used only for one-to-many relationships.

The field names are passed in a hash that associates a field name with a field descriptor. The field descriptor may be either a hash or a string. The hash uses the following fields:

• class

• coll

• back

Mandatory field class specifies the class of the elements.

Optional field coll sets the name the column containing the id of the containing object. This defaults to 'C_m', where 'C' is the class of the containing object, and 'm' is the field name.

Optional field back sets the name of a field that is inserted in the elements. That field acts as a demand-loaded, read-only reference to the object containing the collection.

If the descriptor is a string, it is interpreted as the name of the element's class. This is equivalent to specifying only the class field in the hash variant.