Tangram::Type::Set::FromOne (3pm)

   use Tangram;

   # or
   use Tangram::Core;
   use Tangram::Type::Set::FromOne;

   $schema = Tangram::Schema->new(

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

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

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

This class maps references to Set::Object collections in an intrusive fashion. The persistent fields are grouped in a hash under the \*(C`iset\*(C' 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.

\s-1CAUTION:\s0 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 Mandatory field \*(C`class\*(C' specifies the class of the elements.

• aggreg Optional field \*(C`aggreg\*(C' specifies that the elements of the collection must be removed (erased) from persistent storage along with the containing object. The default is not to aggregate.

• back Optional field \*(C`back\*(C' 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.

• coll Optional field \*(C`coll\*(C' 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 (after passing through the normalisation function), and 'm' is the field name.

• deep_update Optional field \*(C`deep_update\*(C' specificies that all elements have to be updated automatically when \*(C`update\*(C' is called on the collection object. Automatic update ensures consisitency between the Perl representation and the \s-1DBMS\s0 state, but degrades update performance so use it with caution. The default is not to do automatic updates.

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