Question

I am trying to modify model coming from View and then update my database using that model. My code can be seen below:

public ActionResult Edit(Saving saving)
    {
        if (ModelState.IsValid)
        {
            Int32[] ids = saving.CatIds.Split(',').Select(n => Convert.ToInt32(n)).ToArray();
            foreach (var category in db.Category.Where(m => ids.Contains(m.id)).ToList())
                saving.Category.Add(category);
            db.ObjectStateManager.ChangeObjectState(saving, EntityState.Modified);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        return View(saving);
    }

my code gives this error:

The object cannot be attached because it is already in the object context. An object can only be reattached when it is in an unchanged state.

and if I try this code:

public ActionResult Edit(Saving saving)
    {
        if (ModelState.IsValid)
        {
            Int32[] ids = saving.CatIds.Split(',').Select(n => Convert.ToInt32(n)).ToArray();
            foreach (var category in db.Category.Where(m => ids.Contains(m.id)).ToList())
                saving.Category.Add(category);
            db.ObjectStateManager.ChangeObjectState(saving, EntityState.Unchanged); 
            db.Saving.Attach(saving);
            db.ObjectStateManager.ChangeObjectState(saving, EntityState.Modified);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        return View(saving);
    }

I am getting the error below:

Violation of PRIMARY KEY constraint ‘PK_ProductCategory_1’. Cannot insert duplicate key in object ‘dbo.ProductCategory’.

I dont know what to do and how to solve it. Any help will be appreciated. Thank You

Answer 1

Have you tried to just Attach it and then modify the properties?

if (ModelState.IsValid)
{
    db.Saving.Attach(saving);

    Int32[] ids = saving.CatIds.Split(',').Select(n => Convert.ToInt32(n)).ToArray();
    foreach (var category in db.Category.Where(m => ids.Contains(m.id)).ToList())
        saving.Category.Add(category);
    db.SaveChanges();

}