Error when trying to update entity using Entity Framework 4

Question

I have the following Edit method:

[HttpPost]
public ActionResult Edit(Movie movie)
{
    try
    {
        _db.ApplyCurrentValues("Movies1",movie);
        _db.SaveChanges();
        return RedirectToAction("Index"); 
     }
     catch
     {
         return View();
     }
 }

I get the error below when I run it:

An object with a key that matches the key of the supplied object could not be found in the ObjectStateManager. Verify that the key values of the supplied object match the key values of the object to which changes must be applied.

A couple points:

I did not get the error the first time I did an update, only subsequent updates.
Movies1 is the the name of the EntitySet when I view the edmx designer. Is this what it shold be or should it be the name of the table (Movie)?
I have seen things regarding Attach, but I am confused as to what exactly that is.

Eranga · Accepted Answer · 2012-01-13 00:49:33Z

2

Inorder to apply current values an entity with that given key should be present in ObjectStateManager. The documentation for the ApplyCurrentValues states

Copies the scalar values from the supplied object into the object in the ObjectContext that has the same key.

You can attach the entity and apply current values.

    _db.Movies.Attach(movie);
    _db.ObjectStateManager.ChangeState(movie, EntityState.Modified);
    _db.SaveChanges();

edited Jan 13, 2012 at 0:49

answered Jan 12, 2012 at 16:43

Eranga

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2 Comments

Slauma Over a year ago

I think reloading from DB instead of calling Attach would be a better example. Your code snippet removes the exception, but is somehow an empty operation because you are updating an entity with itself = No changed properties = No UPDATE to DB.

Eranga Over a year ago

@Slauma Yes. Thanks for noticing the issue. Updated answer to change the state of the object.

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