4 - Create a New Association Subclass

Owned by Stephen Fuqua
Last updated: Feb 22, 2023 by Stephen Fuqua
2 min read

Problem

The design of a MetaEd model requires the subclassing of an association.  

Solution

Create a new association subclass in the MetaEd source files and reference it where necessary. Build MetaEd. All technical artifacts related to the new association subclass will be updated.

Supported Association Subclasses

GeneralStudentProgramAssociation is the only Association that can be subclassed. MetaEd provides validation warnings if subclassing of other Associations is attempted.

When an existing association needs additional data to support a specialization of the model, it should be subclassed. The naming convention should follow the naming convention for associations with a semantic discriminator indicating what the specialization of data is for this new type. The base association name is the original association to build on. No property in this type can be marked as is part of primary key. Creating a subclass does not affect the original association. Instead it creates a new type that uses the original association as a base and adds new data.

Consider the following declarations:

Association GeneralStudentProgramAssociation
    documentation "This association represents the Program(s) that a student participates in or is served by."
    domain entity Student
        documentation "The Student associated with the Program."
    domain entity Program
        documentation "The Program associated with the Student."
    ...
    reference EducationOrganization
        documentation "The EducationOrganization where the Student is participating in or receiving the Program services."
        is part of identity
    ...
Association StudentXYZProgramAssociation based on EdFi.GeneralStudentProgramAssociation
	documentation "This association represents the XYZ program."
	string XYZProgramCode
            documentation "The program code representing this XYZ."
        is required
            max length 10

StudentXYZProgramAssociation is a new Association Subclass which is based on GeneralStudentProgramAssociation. Like its parent, the subclass associates Student and Program and has a reference to EducationOrganization. StudentXYZProgramAssociation modifies GeneralStudentProgramAssociation with the addition of an XYZProgramCode.