Question

I am trying to use the Extensibility Method Definitions from my datacontext.designer.cs file to do some validation.

So I created a new file and added this code:

public partial class LawEnforcementDataContext : System.Data.Linq.DataContext {      partial void InsertCourse(Course instance) // this definition copied from generated file     {         ValidateCourse(instance);         this.ExecuteDynamicInsert(instance);     }      partial void UpdateCourse(Course instance) // this definition copied from generated file     {         ValidateCourse(instance);         this.ExecuteDynamicUpdate(instance);     }      private void ValidateCourse(Course instance)     {         if (instance.StartDate > instance.EndDate)         {             throw new ApplicationException('Start date cannot be later than end date.');         }     } } 

I can’t compile because of these errors:

Error   1   No defining declaration found for implementing declaration of partial method 'LawEnforcementDataContext.InsertCourse(reservation.lawenforcement.Course)' Error   2   No defining declaration found for implementing declaration of partial method 'LawEnforcementDataContext.UpdateCourse(reservation.lawenforcement.Course)' 

I don’t see what I am doing wrong. I have done this before. Also, after adding the above code, in code that references the classes created by the LINQ to SQL, it complains that my entity types no longer exist. It’s as if the partial class LawEnforcementDataContext is completely taking over the generated code.

EDIT

Here are the other halves of the partial declarations from the generated code:

    // the class     public partial class LawEnforcementDataContext : System.Data.Linq.DataContext      // the methods     partial void InsertCourse(Course instance);     partial void UpdateCourse(Course instance); 

Answer 1

Your two partial classes are defined in different namespaces, so the compiler does not ‘share’ them.

There is a setting under Properties in the DBML designer for this. Perhaps it reset?