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6 - Add Reference Property

Problem​

The design of a MetaEd model requires the addition of a reference property to an entity.

Solution​

Identify the affected entity in the MetaEd source files. Add the reference property and rebuild MetaEd. All technical artifacts related to the property will be updated.

Discussion​

A reference property defines a reference to a domain entity or association for the containing entity. The domain entity name or association name should be the name of an existing entity. If the containing entity defines more than one property of the same entity type, the role name can be used to differentiate between the properties (see the Add Reference with Role Name Cookbook entry).

Consider the following code snippets:

Abstract Entity EducationOrganization 
    ...
Domain Entity Program
 documentation "This entity represents any program designed to work in conjunction with..."
    string ProgramId
        documentation "A unique number or alphanumeric code assigned to a program."
        ...

Program does not currently have a reference to an EducationOrganization, but it turns out that it should be part of Program's identity. After adding a reference property, the code for Program should look like:

Domain Entity Program
 documentation "This entity represents any program designed to work in conjunction with..."
    string ProgramId
        documentation "A unique number or alphanumeric code assigned to a program."
        ...
    domain entity EducationOrganization
        documentation "Relates the program to an EducationOrganization."
        is part of identity
    ...
warning

In a complex model it is possible that fields from one reference entity – that is, the identity fields – will overlap with identity fields from another reference, or overlap with fields that are on the base class. In such situations, the modeler may need to provide additional information on if these fields are to be seen as identical. For this reason, we strongly suggest that developers of complex values review these sections: