1. A computer implemented method for accessing a data store, comprising: instantiating an entity object in a server computer, the entity object including a plurality of attributes, the plurality of attributes including a superset of all attributes of a set of underlying object types, the plurality of attributes further including a discriminator attribute having a value, the value determining which type of the underlying object types the entity object should behave as; retrieving an instance of a helper object for the underlying object type, the instance of the helper object determined by the value of the discriminator attribute; passing the entity object to the helper object; and invoking at least one method of the helper object to store values for plurality of attributes of the entity object into the data store.