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Many-to-many insert with Entity Framework

Anonymous User 10137 28-Sep-2013

I'm two entities in my Data Model, for example User and Role, both having the ID field as primary key. There's a many-to-many relationship between them. In the database there are three tables: Users, Roles and UsersRoles junction table.

I'm trying to add a new user to the Users table:

using(var myContext = new MyContext)

{

   var user = new User() { ... };

   user.Roles.Add(new Role() { ID = 1 });

}


The same role can be already be used by another Users, so, when I try to add a new User with the same Role, I become Primary key violation as EF tries to add a new record to the Roles table.

Is there any way to tell the Entity Framework not to add a new record to the Roles table, when such role already exists, but only update the Users and UserRoles tables? EF version 1.0

Thanks in advance.

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Updated on 28-Sep-2013
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1 Answers

Anonymous User

Anonymous User

28-Sep-2013

Hey Jay!

If the role already exists in the DB you must EF tell that by attaching the role to the context:

using(var myContext = new MyContext)

{

    var role1 = new Role() { ID = 1 };

    myContext.Roles.Attach(role1);

    var user = new User() { ... };

    user.Roles.Add(role1);

    myContext.Users.AddObject(user);

    myContext.SaveChanges();

}


(I hope that this also works the same way in EF 1.)

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