Task 3 - Limit the number of talks per session

Goal

Aim of this task is to limit the number of talks that user can add to single session.

Objectives

Frontend

• At the creation talk template we need to display the number of talks
• if session has already maximum number of talks:
  • disable "Add talk" button
  • mark talks number counter with red color

Backend

• Add new field to Session model (max_talks)
• Remember to add a migration after changing the model.
• Run migration in order to actually change state of the database.
• Implement validation at the talk serializer when creating new talk.