title: UUIDField in Django (error:operator does not exist: integer = uuid)
body: <p>i want to use uuid field as my id (primary key) but there is something wrong with it and i can't fix it ...</p>
  
  <p>this is my model</p>
  
  <pre><code>class Course(models.Model):
  
      id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
      title = models.CharField(max_length=90)
      description = models.TextField()
      author = models.CharField(max_length=60)
      image = models.ImageField(upload_to='courses/images')
      intro_video = models.FileField(upload_to='courses/videos')
      free = models.BooleanField(default=False)
      price = models.CharField(max_length=60, blank=True)
      completed = models.BooleanField(default=False)
      duration = models.CharField(max_length=30, blank=True)
      created_at = models.DateTimeField(auto_now_add=True)
  
      def __str__(self):
          return self.title
  </code></pre>
  
  <p>when i try to add a new course it gave's me this error</p>
  
  <pre><code>ProgrammingError at /admin/courses/course/add/
  operator does not exist: integer = uuid
  LINE 1: ..., "created_at" = NULL WHERE "courses_course"."id" = 'a130811...
                                                               ^
  HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
  
  Exception Type: ProgrammingError
  Exception Value: operator does not exist: integer = uuid
  </code></pre>
  
  <p>my database is postgresql</p>
  
  <p>please help me.</p>