Menu
I am importing a database into Entity Framework and I'm having trouble with a many-to-many relationship that looks like this:
My understanding is that if the "join table" (the middle one) contains only two fields (the foreign keys) then EF will automatically remove the middle table and create a many-to-many relationship. Unfortunately I don't have control over the database schema, so does anyone know if there's a way to replicate that behaviour manually?
For the record, there is no purpose behind that Id field in Employee_Employee_Type, it's just poorly designed.
990
To configure many-to-many relationship Using Data Annotations, you need to create the Join Table in the model. The Join Table BookCategory will have properties for the primary key of both the table. It will have two navigational properties one each for Book and Category class.
A self-referencing many-to-many relationship exists when a given record in the table can be related to one or more other records within the table and one or more records can themselves be related to the given record.
According to Entity Framework 4 recipes, page 554, this is how you'd do it (it's not pretty).
Essentially, you want to create a View of the Employee_Employee_type mapping table, but without the extra column, then manually map it to the other two tables. Below are pics of the relevant pages. I think (and hope!) this is covered by academic free-use copyright laws...
The book is fantastic, BTW, so I'd recommend buying it. Hopefully that will endear me to the author if he happens upon this.
151
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
