CODEWITHSUNDEEP
asp.net-mvc-3entity-framework-4
Ulises
Ulises

Reputation: 13429

How do I delete a related object with a 1 to 1 relationship in the Entity Framework?

I'm using EF Model First and in my Employee class I have a Manager property with a 1 to 1 relationship to itself, the Employee class:

public partial class Employee
{
    public Employee()
    {          
    }

    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public virtual Employee Manager { get; set; }
}

Now, when I get an existing object from the database and change the manager with:

employee.Manager = otherEmployeeInstance;
Context.Entry(employee).State = System.Data.EntityState.Modified;
Context.SaveChanges();

It works just fine; however, if I want to remove the manager this will not work:

employee.Manager = null;

It looks to me that I first need to "load" the manager (Employee) instance into the context since this makes it work:

var dummyVar = employee.Manager.Id;
employee.Manager = null;

So the question is, what's the best (proper) way to remove a related object?

Upvotes: 1

Views: 1608

Answers (1)

Amirhossein Mehrvarzi
Amirhossein Mehrvarzi

Reputation: 18974

obviously, when you want to delete an entity of the one-to-one relationship, the EF doesn't allow to delete it without preparing it before. that is, removing any dependent entity information from that entity. Remember, we are using Relational Database system and any breaking relation without any coordination causes to anomaly and failure. When you want to remove a relation, you can use this at your controller: 

employee.Remove(Manager);//Automatically Removes Navigational Properties at both entities
db.SaveChanges();

Instead of this :

employee.Manager = null;

Upvotes: 2

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