What is the proper way to remove a reference using the .NET 4 Entity Framework?

Question

I have an instance of TPM_PROJECTVERSION called projectVersion , which has a property called TPM_USER5 which is of type TPM_USER . A TPM_PROJECTVERSION can have zero or one TPM_USER5 references (Sorry, I didn't come up with these names.)

When the user clicks a Delete button, I want to remove this reference, thus setting the column in the database to null. I've tried the following:

projectVersion.TPM_USER5 = null;

However, when I call context.SaveChanges() , the column is not updated and nothing happens. Under the debugger, I can see that projectVersion.TPM_USER5 is indeed null, and I also see that projectVersion.TPM_USER5Reference.IsLoaded is true. I've also tried:

context.DeleteObject(projectVersion.TPM_USER5);

If I do this, when I call context.SaveChanges() , I get the exception:

{"ORA-02292: integrity constraint (TPMDBO.TPM_PROJECTCHANGES_TPM_US_FK1) violated - child record found"}

I'd be happy to post more information about the entity mappings, but not sure exactly what's relevant. Any ideas?

Answer 1

If I understand correctly thus you removing only navigation property (TPM_USER5). Try set primitive property (TPM_USER5ID? - probably your db column name) to null.

Each navigation property must have relevant primitive property (not POCO entities) and you can use both to associate user to TPM_USER5 (primitive property - set id, navigation property - set reference).