Why would Entity Framework carry out update when RowVersion has changed? - asp.net-mvc

Question

I'm having a problem trying to catch a DbUpdateConcurrencyException using Entity Framework 5. The problem that I'm having is that EF is updating the record, even though the RowVersion (Timestamp) property has changed since the row was retrieved from the database. The HttpGet Edit action gets a user profile from the database and I pass the values to a ViewModel, including a list of checkboxes for the user to select the roles and pass this to the view.
public ActionResult Edit(int id = 0)
{
UserProfile userProfile = unitOfWork.UserProfileRepository.GetUserProfileById(id);
UserProfileEditViewModel viewModel = new UserProfileEditViewModel
{
UserId = userProfile.UserId,
UserName = userProfile.UserName,
FirstName = userProfile.FirstName,
LastName = userProfile.LastName,
Email = userProfile.Email,
RowVersion = userProfile.RowVersion,
};
var allRoles = unitOfWork.RoleRepository.GetAllRoles();
var userProfileRoles = userProfile.Roles;
foreach (var role in allRoles)
{
if (userProfileRoles.Contains(role))
{
viewModel.Roles.Add(new RoleViewModel
{
RoleId = role.RoleId,
RoleName = role.RoleName,
Assigned = true,
});
}
else
{
viewModel.Roles.Add(new RoleViewModel
{
RoleId = role.RoleId,
RoleName = role.RoleName,
Assigned = false,
});
}
}
return View(viewModel);
}
I then have a basic edit view that has a HiddenFor for the RowVersion property.
#model MvcWebsite.ViewModels.UserProfileEditViewModel
#{
ViewBag.Title = "Edit";
}
<h2>Edit</h2>
#using (Html.BeginForm()) {
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
<fieldset>
<legend>UserProfile</legend>
#Html.HiddenFor(model => model.UserId)
#Html.HiddenFor(model => model.UserName)
#Html.HiddenFor(model => model.RowVersion)
<div class="editor-label">
#Html.LabelFor(model => model.UserName)
</div>
<div class="editor-field">
#Html.DisplayFor(model => model.UserName)
</div>
<div class="editor-label">
#Html.LabelFor(model => model.FirstName)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.FirstName)
#Html.ValidationMessageFor(model => model.FirstName)
</div>
<div class="editor-label">
#Html.LabelFor(model => model.LastName)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.LastName)
#Html.ValidationMessageFor(model => model.LastName)
</div>
<div class="editor-label">
#Html.LabelFor(model => model.Email)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.Email)
#Html.ValidationMessageFor(model => model.Email)
</div>
<div class="editor-field">
<table>
<tr>
#Html.EditorFor(model => model.Roles)
#Html.ValidationMessageFor(model => model.Roles)
</tr>
</table>
</div>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
}
<div>
#Html.ActionLink("Back to List", "Index")
</div>
#section Scripts {
#Scripts.Render("~/bundles/jqueryval")
}
I then have a HttpPost Edit action that takes the data from the viewModel and adds it to a user profile that I've retrieved from the database. I then change the properties of this profile to those that were retrieved from the client, including the RowVersion (changing the RowVersion back to its original state)
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(UserProfileEditViewModel model)
{
try
{
if (ModelState.IsValid)
{
var userProfile = unitOfWork.UserProfileRepository.GetUserProfileById(model.UserId);
userProfile.UserName = model.UserName;
userProfile.FirstName = model.FirstName;
userProfile.LastName = model.LastName;
userProfile.Email = model.Email;
userProfile.RowVersion = model.RowVersion;
var roleAssignments = model.Roles;
foreach (var roleAssignment in roleAssignments)
{
if (roleAssignment.Assigned)
{
userProfile.Roles.Add(unitOfWork.RoleRepository.GetRoleById(roleAssignment.RoleId));
}
else
{
userProfile.Roles.Remove(unitOfWork.RoleRepository.GetRoleById(roleAssignment.RoleId));
}
}
unitOfWork.UserProfileRepository.UpdateUserProfile(userProfile);
unitOfWork.Save();
return RedirectToAction("Details", new { id = userProfile.UserId });
}
}
catch (DbUpdateConcurrencyException ex)
{
... Code omitted for brevity
}
}
return View(model);
}
I test this by opening the edit page twice. I then update the second page and click save, which commits the changes to the database. The database shows that the row version has in fact been changed to reflect the update. When I change the second page and click save, even though the row version of this profile is different from the row version that was created when the first profile was saved, the changes are saved to the database also. I've checked that indeed, the row version in the database is actually changed twice.
I have a funny feeling that I'm missing the obvious here, but any help would be greatly appreciated.

Answer 1

typically you don't change the row version explicitly. this would be handled by the ORM itself. What you would do is compare the view model version to the domain version. if they do not match you then need to handle that scenario.
if(viewmodel.RowVersion != domainModel.RowVersion)
{
//model has changed, notify user...
}
else
{
//update domain model
//save changes
}
You could further prevent this by making RowVersion immutable
class domainmodel
{
...
public int RowVersion {get; private set;}
}