Working with checkboxes and querying the database in Django - django

Question

My goal is to create a page that lists all the courses available in the database and have the user select which courses they would like to be a tutor for.
I have a CustomUser model, a courses model, and finally a TutorTeachesCourse model that takes user and courses as foreign keys.
# model.py
from django.contrib.auth.models import AbstractUser
class CustomUser(AbstractUser):
is_tutee = models.BooleanField(default=False)
is_tutor = models.BooleanField(default=False)
courses = models.ManyToManyField(Courses)
class Courses(models.Model):
course_name = models.CharField(max_length=100, null = False)
course_number = models.CharField(max_length=100, null = False)
department = models.ForeignKey(Department, on_delete=models.CASCADE)
course_description = models.CharField(max_length=1000, blank=True)
#tutor = models.ManyToManyField(CustomUser) #moved m2m relationship to user model
objects = models.Manager()
def __str__(self):
return self.course_name
# forms.py
class EditTutoredCoursesForm(forms.Form):
model = CustomUser
course = forms.ModelMultipleChoiceField(
queryset = Courses.objects.all(),
widget = forms.CheckboxSelectMultiple,
)
def clean(self):
cleaned_data = super(EditTutoredCoursesForm, self).clean()
is_tutor = cleaned_data.get('is_tutor')
if not is_tutor:
raise forms.ValidationError('Validation error.')
def save(self,commit=True):
rel=super(EditTutoredCoursesForm,self).save(commit=False)
rel.is_tutor=self.cleaned_data['is_tutor']
if commit:
rel.save()
return rel
# views.py
def edit_tutored_courses(request):
user = request.user
if request.method == 'POST':
form = EditTutoredCoursesForm(request.POST)
if form.is_valid():
user.courses.set(form.cleaned_data['courses'])
user = form.save(commit=True)
messages.success(request, 'Success!')
return redirect(reverse('view_profile'))
else:
form = EditTutoredCoursesForm()
context = {
'form' : form,
}
return render(request, 'edit_tutored_courses.html', context)
And here the page where the user selects/unselects the courses they wish to tutor/not tutor.
# edit_tutored_courses.html
<table style="width:50%">
<tr>
<th>Course Name</th>
</tr>
<form method="POST" action="">
{% csrf_token %}
{% for is_tutor in form %}
{% for course in is_tutor %}
<tr>
<td>{{ course }}</td>
<td>{{ user }}</td>
</tr>
{% endfor %}
{% endfor %}
</table>
<input type="submit" value="Save Changes"/>
</form>
I can display the courses on my page but I don't know how to make changes to the database. I want the checkboxes to mean that once I click "submit" the table TutorTeachesCourses populates with that user with the checked courses, and if I uncheck the boxes it means it deletes the existing one. (That means I also need to make the page automatically check the boxes that exists int he database. How do I do all of this?