实体框架-保存数据库更改不起作用

Question

When submitting a form and passing in my model (Forms) I am trying to save the changes to my DB.

Forms model has a PeopleInvolved object as a property.

The model is updated successfully, the changes also get added to the peopleInvolved object successfully, however, the SaveChanges() call doesn't save anything.

.NET Framework 4.5.1 - EF 6.1.1

public class Forms
{
        public int Id { get; set; }
        public string UserId { get; set; }
        public PeopleInvolved PeopleInvolved { get; set; }     
}

public async Task<ActionResult> EditForm(Forms model, string returnUrl)
{
    ViewData["ReturnUrl"] = returnUrl;
    ApplicationUser user = await GetCurrentUserAsync();

    if (!ModelState.IsValid) 
        return RedirectToAction("Index", model);

    if (model.PeopleInvolved != null)
    {
        PeopleInvolved peopleInvolved = _db.PeopleInvolved.Single(x => x.FormId == user.FormId);
        peopleInvolved = model.PeopleInvolved;

        _db.SaveChanges();

        return RedirectToLocal(returnUrl + "?PeopleInvolved?Success");
    }
}

Answer 1

You didn't actually change anything from the database.

Your call to the database returned a PeopleInvolved object and stored a reference to it in the peopleInvolved variable. Then you change that variable to be a reference to the PeopleInvolved property on the model object. You never actually change the object returned from the database call.

Simplistic solution is to do something like

peopleInvolved.Property1 = model.PeopleInvolved.Property1;
peopleInvolved.Property2 = model.PeopleInvolved.Property2;

to update the actual object that was returned from the database.

Answer 2

You can update like this. If you have to override model.PeopleInvolved.FormId with user.FormId update that property.

db.PeopleInvolved.Attach(model.PeopleInvolved);
db.Entry(model.PeopleInvolved)).State =  System.Data.Entity.EntityState.Modified;    
db.SaveChanges();