实体框架多对多

Question

Since upgrading to EF 6.1.3 I am unable to save anything to the DB.

I get an error:

"Unable to update the EntitySet 'ProjectTask' because it has a DefiningQuery and no element exists in the element to support the current operation."

The Tables define a many to many relationship:

Project

• Id INT PK

ProjectTask

• ProjectId INT
• TaskId INT

Task

• Id INT PK

with all foreign keys defined. Pretty standard.

Some posts indicated that the joining table ProjectTask must have a primary key defined. But, if I do that EF creates the ProjectTask class in the data model which is not good.

Answer 1

As a few people mentioned. Creating a composite key on ProjectTask table was the solution.

ALTER TABLE dbo.ProjectTask
    ADD CONSTRAINT ProjectTask_ProjectId_TaskId UNIQUE (ProjectId, TaskId)