Entity Framework 6 - Many-to-Many Table with Additional Information

Question

Seems I am not allowed to post images, so let me describe the image. It is a SQL table diagram showing the relationships between 4 tables. The Tables are:

1. People
   • Id
   • FirstName
   • LastName
2. PhoneNumbers
   • Id
   • Number
3. PhoneNumberTypes
   • Id
   • Name
   • Description
4. PeoplePhoneNumbers
   • PersonId
   • PhoneNumberTypeId
   • PhoneNumberId

The two main tables are People and PhoneNumbers. There is also a PhoneNumberTypes that describes the type of PhoneNumber (Home, Work, etc).

The PeoplePhoneNumbers table serves as a Many-To-Many relationship table between People and PhoneNumbers. However it also connects to PhoneNumberTypes to describe the relationship.

I have been trying to figure out how to handle this Entity Framework because EF does not allow you to add additional information to the Association(Many-To-Many) Table.

Besides the PhoneNumberType info, I also find that their are additional data pieces I need to record in the Association Table like "Start Date", "End Date", etc.

The only solution I have come up with so far is to create an entity in EF that combines the fields in PhoneNumberTypes, PhoneNumbers and PeoplePhoneNumbers into a single entity. Then use SQL stored procedures for CRUD operations against it.

I would prefer a more EF centric solution. Does anyone know of one?

Answer 1

PhoneNumberTypes should not be linked to PeoplePhoneNumbers. Let PeoplePhoneNumbers be what it is and only a junction table. PhoneNumberTypes should be linked to PhoneNumbers. EF should be able to create this setup by convention. Additional information describing phone number should also be linked off of PhoneNumbers. This design adheres to more Domain Driven Design (DDD) principles and also generates a better database design as well.