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Editorial Team
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Asked: 2026-05-26T09:14:25+00:00

Say I have a client dataset CDSPerson that acts as a wrapper around a

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Say I have a client dataset CDSPerson that acts as a wrapper around a Persons database table. Say I have another table, PersonBenefits, that joins 1:1 back to the Persons table.

Say I wrap a Delphi class around CDSPerson, PersonClass, and another class around CDSPersonBenefits, PersonBenefitsClass, to read and write records. PersonBenefitsClass inherits from PersonClass so it can provide data from both tables. I’d like to be able to write data back to either table through PersonBenefitsClass.

Has anyone developed a clean way to handle the SQL query, provider flags and commit logic in the inherited class so that (a) fields stay aligned with the parent class and (b) both database tables can be updated?

Is there a reference for this that I can’t find? Is this just a bad idea? I’m using Delphi 2007.

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1 Answer

  1. Editorial Team

    If you’re going to develop a business-object-to-database mapping framework, (commonly known as ORM, Object-Relational Mapper,) you’re going to need to put in a bit of architecture to make relationships like this work properly. Here’s one way to do it:

    PersonClass and BenefitsClass both inherit from BusinessObjectClass. BusinessObjectClass is a base class that contains the general logic to interact with the dataset. It has a list object of some sort that contains a list of relation objects.

    Each relation object is a special object that contains either one or a list of BusinessObjectClass descendants, plus extra data describing the foreign-key relationship between the two tables. When BusinessObjectClass does its queries and its updates, it needs to iterate through all its relation objects and have them do their own queries and updates as appropriate.

    In your composite object, (PersonWithBenefitsClass,) in the constructor, call inherited and then set up a relation object that describes the related BenefitsClass. Make sure that any inserts of new objects are done in the right order to preserve referential integrity.

    That’s the basic idea. (One basic idea. There are probably plenty of other ways to do it.) I’ll leave the details of exactly how you implement it up to you.

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