title: ASP.NET Core MVC dropdown list on _layout page to a Session variable
body: <p>I have been looking for a good example of this but all i find is regular ASP.NET MVC.  Although i would like to populate the drop down list from a database, and i already have a controller that pulls that for another page.  For now, all i want is a simple 5 selection drop down list that i can add manually on the layout page with the Nav Bar.  How would i make that selection dynamically a session and will remain the same on every page until another is selected?</p>
  
  <p>reason: This selection is the location of offices and each one has different data specific for that location, so i will use that Session variable in all controllers/Views.</p>