Add a Custom property to ASP.NET MVC Identity after user login
<p>I am trying to add an item to the users Identity, but I think this could also be done another way.</p>

<p>I have added a few custom fields to the User Identity, but what I am trying to do is once the user has successfully logged in, I check if they are assigned to multiple branches(Store Locations) and then offer a list for the user to select which Branches they want data to be displayed for. </p>

<p>I have done this successfully, but now I want to store each of the branches in the users session/ cookie/ Identity (not sure what terminology to use). The user is displayed a number of checkboxes, and once they click save, I am unsure of what to do.</p>

<p>I need to save it in this function:</p>

<pre><code>[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SelectBranch(params string[] branchNames)
        {

            foreach (var branch in branchNames)
            {
                //add branch to session/cookie/identity

            }

            return RedirectToAction("Index");
        }
</code></pre>

<p>What steps do I need to take to be able to do this?</p>