title: Reverse for 'detail' with arguments '('',)' not found. 1 pattern(s) tried: ['(?P<pk>[0-9]+)/$']
body: <p>Am trying to develop an app for student management. Every thing seems to be working fine. but am receiving an errors at some point. If i open the list view it shows all the student, if i click a student photo it will open a detail view of that student for me, then if i click add button inside the view it will show me (NoReverseMatch at <code>/add_subj/3/</code>
  Reverse for 'detail' with arguments <code>'('',)'</code> not found. 1 pattern(s) tried: <code>['(?P[0-9]+)/$']</code> ). I want to be able to add subject to a particular id. Please need some help, am new in django.</p>
  
  <p>This is the link to my models.py, views.py and urls
  <a href="https://gist.github.com/AnyiLloyd/a963e9e3f52aa8f46fd7ef9a6ec0dddb" rel="nofollow noreferrer">https://gist.github.com/AnyiLloyd/a963e9e3f52aa8f46fd7ef9a6ec0dddb</a></p>