title: How to display model's primary key in django during update
body: <p>In some of my models I have used the primary key defined by the system (Django) whereas in some others I have defined my own primary keys. </p>
  
  <p>In the second instance (i.e. for models with custom primary keys), while updating / changing a record, I am able to show the primary key (as a readonly field) in the page being presented to the user (through a template). This is what I am unable to replicate for models with system defined primary key.</p>