How to save a ManyToMany relationship from a ModelForm in Django - django

Question

I'm not sure to save my ManyToMany relationship. I found my exact problem in this thread: Django embedded ManyToMany form, except instead of Sales and Products models, I have models that make up a movie.
I tried the solution, but I receive a syntax error. I don't understand how Django should link the EquipmentModel, LightModel, and ActorModel to the ManyToMany relationship in MovieModel. So far (before trying the other thread's solution), the CharFields that are displayed on the form for LightModel, EquipmentModel, and ActorModel are not linked to the ManyToManyField in MovieModel. So when I save the forms and try to access a particular Movie's actors, all I see is a blank list. The solution from the other thread seems to make sense since it tries to link the models to the ManyToMany relationship in MovieModel, but I don't understand how Django knows which MovieModel to add to (how does it get the correct movieID?).
On a side note, is there a way to check for duplicate movies when the user presses the 'Submit' button on the form? I want to avoid creating duplicates.
views.py:
def add_movie(request, movieID=""):
if request.method == "POST":
form = MovieModelForm(request.POST)
eform = EquipmentModelForm(request.POST)
lform = LightModelForm(request.POST)
aform = ActorModelForm(request.POST)
print 'checking form'
print request.POST.items()
if form.is_valid() and eform.is_valid() and lform.is_valid() and aform.is_valid():
print 'form is valid'
movie_to_add = form.save()
e = eform.save()
l = lform.save()
a = aform.save()
movie_to_add.actors.add(a)
movie_to_add.lights.add(l)
movie_to_add.equipments.add(e)
# return HttpResponseRedirect('/data')
else:
# code for create forms ....
return render_to_response('add_movie.html', {'form':form, 'eform':eform,'lform':lform, 'aform':aform,}, context_instance=RequestContext(request))
Other code that may help:
forms.py
class LightModelForm(forms.ModelForm):
class Meta:
model = LightModel
class ActorModelForm(forms.ModelForm):
class Meta:
model = ActorModel
class EquipmentModelForm(forms.ModelForm):
class Meta:
model = EquipmentModel
class MovieModelForm(forms.ModelForm):
class Meta:
model = MovieModel
fields = ("title", "rank")
models.py
class EquipmentModel(models.Model):
equip = models.CharField(max_length=20)
class ActorModel(models.Model):
actor = models.CharField(max_length=20)
class LightModel(models.Model):
light = models.CharField(max_length=20)
class MovieModel(models.Model):
rank = models.DecimalField(max_digits=5000, decimal_places=3)
title = models.CharField(max_length=20)
equipments = models.ManyToManyField(EquipmentModel, blank=True, null=True)
actors = models.ManyToManyField(ActorModel, blank=True, null=True)
lights = models.ManyToManyField(LightModel, blank=True, null=True)
def __str__(self):
return self.title
Edit: removed unnecessary init and fields thanks to DTing
Edit2: Fixed!

Answer 1

There is a whole lot of stuff going wrong here in addition to what spulec said.
Your models.py look okay.
class EquipmentModel(models.Model):
equip = models.CharField(max_length=20)
class ActorModel(models.Model):
actor = models.CharField(max_length=20)
class LightModel(models.Model):
light = models.CharField(max_length=20)
class MovieModel(models.Model):
rank = models.DecimalField(max_digits=5000, decimal_places=3)
title = models.CharField(max_length=20)
equipments = models.ManyToManyField(EquipmentModel, blank=True, null=True)
actors = models.ManyToManyField(ActorModel, blank=True, null=True)
lights = models.ManyToManyField(LightModel, blank=True, null=True)
def __str__(self):
return self.title
You don't need to override the __init__ method on forms if you are not changing anything on init. You also don't need to be explicit about the fields if you want to include them all.
class LightModelForm(forms.ModelForm):
class Meta:
model = LightModel
class ActorModelForm(forms.ModelForm):
class Meta:
model = ActorModel
class EquipmentModelForm(forms.ModelForm):
class Meta:
model = EquipmentModel
class MovieModelForm(forms.ModelForm):
class Meta:
model = MovieModel
fields = ("title", "rank")
your view doesn't really make sense unless for every movie you are trying to add you also want to:
add a new movie to the db using the submitted post data
create one actor object and add to db
create one light object and add to db
create one equipment object and add to db
take those three objects and add them to another movie's m2m relationships.
This other movie is some movie that you pulled from the urlconf and passed to your view, not the one you just created.
This all seems a little strange.
what i think you want to do is create all the equipment, actors and lights objects so they are in your db already, and use the default m2m formfield widget to select them when adding a movie.
so:
forms.py
class MovieModelForm(forms.ModelForm):
class Meta:
model = MovieModel
urls.py:
url(r'^add_movie/$', add_movie)
views.py:
def add_movie(request):
if request.method=='POST':
form = MovieModelForm(request.POST)
if form.is_valid():
form.save()
return HttpResponse('success')
else:
form = MovieModelForm()
context = {'form':form }
return render_to_response('some_template.html', context,context_instance=RequestContext(request))
you could combine adding actors, lights, and equipment into the same form but that's a bit much for me to write out right now.
As far as modifying your original code to add those lights, actors, and equipment to the movie you just created, you could do this:
if form.is_valid() and eform.is_valid() and lform.is_valid() and aform.is_valid():
new_movie = form.save()
e = eform.save()
l = lform.save()
a = aform.save()
new_movie.actors.add(a)
new_movie.lights.add(l)
new_movie.equipments.add(e)

Answer 2

Change it to:
movie_to_add = get_object_or_404(MovieModel, id=movieID)