ASP.NET MVC Concurrency with RowVersion in Edit Action
- by Jorin
I'm wanting to do a simple edit form for our Issue Tracking app. For simplicity, the HttpGet Edit action looks something like this:
// Issues/Edit/12
public ActionResult Edit(int id)
{
var thisIssue = edmx.Issues.First(i => i.IssueID == id);
return View(thisIssue);
}
and then the HttpPost action looks something like this:
[HttpPost]
public ActionResult Edit(int id, FormCollection form)
{
// this is the dumb part where I grab the object before I update it.
// concurrency is sidestepped here.
var thisIssue = edmx.Issues.Single(c => c.IssueID == id);
TryUpdateModel(thisIssue);
if (ModelState.IsValid)
{
edmx.SaveChanges();
TempData["message"] = string.Format("Issue #{0} successfully modified.", id);
return RedirectToAction("Index");
}
return View(thisIssue);
}
Which works wonderfully. However, the concurrency check doesn't work because in the Post, I'm re-retreiving the current entity right before I attempt to update it. However, with EF, I don't know how to use the fanciness of SaveChanges() but attach my thisIssue to the context. I tried to call edmx.Issues.Attach(thisIssue) but I get
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.
How do I handle concurrency in MVC with EF and/or how do I properly Attach my edited object to the context?
Thanks in advance
