def join_course(self, course_id, code=None):
from courses.models import Course, UserCourse # do this because users.py & courses.py import each other
if code is not None:
course = Course.objects.filter(code=code).first()
elif course_id is not None:
course = Course.filter(pk=course_id).first()
else:
return ''
if course is None:
return 'Invalid code'
if UserCourse.objects.filter(user=self, course=course).first():
return 'You are already in the course'
if course.teacher.pk == self.pk:
return 'You teach that course'
UserCourse(user=self, course=course).save()
return course
