NAME

       Tangram::Type::Array::FromMany - map Perl arrays using a link table

SYNOPSIS

          use Tangram;

          # or
          use Tangram::Core;
          use Tangram::Type::Array::FromMany;

          $schema = Tangram::Schema->new(

             classes => { Company => { fields => {

             array =>
             {
                # long form
                employee =>
                {
                   class => 'Person',
                   table => 'Company_employees',
                   coll => 'company',
                   item => 'employee',
                   slot => 'slot'
                },

                # short form
                assets => 'Asset',
             }

DESCRIPTION

       Maps references to a Perl array. The persistent fields are grouped in a hash under the "array" key in the
       field hash.

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

       Tangram uses a link table to save the state of the collection. The table has three columns, which contain

       •   the id of the container objects

       •   the id of the elements

       •   the position of the element in the array

       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

       •   aggreg

       •   table

       •   coll

       •   item

       •   slot

       •   deep_update

       Mandatory field "class" specifies the class of the elements.

       Optional field "aggreg" 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.

       Optional  field  "table" sets the name of the link table. This defaults to 'C_F', where C is the class of
       the containing object and F is the field name.

       Optional field "coll" sets the name the column  containing  the  ids  of  the  containing  objects.  This
       defaults to 'coll'.

       Optional  field  "item"  sets  the  name  the column containing the ids of the elements. This defaults to
       'item'.

       Optional field "slot" sets the name the column containing the position of the elements. This defaults  to
       'slot'.

       Optional field "deep_update" specificies that all elements have to be updated automatically when "update"
       is called on the collection object. Automatic update ensures consisitency between the Perl representation
       and  the  DBMS  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 "class" field in the hash variant.

perl v5.36.0                                       2022-10-16                Tangram::Type::Array::FromMany(3pm)