Problems with save ManyToMany field data

Question

I have modal with 2 ManyToManyField. I have problems when try to save my form. Why save_m2m() method dont work?

As you see in my form for function field I use ModelChoiceField and for program field I use ModelMultipleChoiceField.

modals.py:

class Requirement(models.Model):
    group_requirement = models.ForeignKey(GroupRequirement, on_delete=models.CASCADE)

    function = models.ManyToManyField("Function")
    program = models.ManyToManyField('Program')

forms.py:

class RequirementForm(forms.ModelForm):
    function = forms.ModelChoiceField(widget=Select2Widget(), queryset=Function.objects.none())
    program = forms.ModelMultipleChoiceField(widget=Select2MultipleWidget(), queryset=Program.objects.none())

    class Meta:
        model = Requirement
        fields = ('function', 'program')

    def __init__(self, all_functions, all_programs, *args, **kwargs):
        super(RequirementForm, self).__init__(*args, **kwargs)
        self.fields['function'].queryset = all_functions
        self.fields['program'].queryset = all_programs

views.py:

def requirement_add(request, project_id, group_requirement_id):
    group_requirement = get_object_or_404(GroupRequirement, pk=group_requirement_id)

    all_functions = Function.objects.filter(project=project_id)
    all_programs = Program.objects.filter(project=project_id)

    if request.method == 'POST':
        requirement_form = RequirementForm(data=request.POST, all_functions=all_functions, all_programs=all_programs)
        if requirement_form.is_valid():
           requirement = requirement_form.save(commit=False)
           requirement.group_requirement = group_requirement
           requirement.save()
           requirement_form.save_m2m()

ERROR:

Traceback (most recent call last):
  File "C:\Users\Nurzhan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\handlers\exception.py", line 39, in inner
    response = get_response(request)
  File "C:\Users\Nurzhan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\handlers\base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\Users\Nurzhan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\handlers\base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\Nurzhan\PycharmProjects\RMS\project\views.py", line 1397, in requirement_add
    requirement_form.save_m2m()
  File "C:\Users\Nurzhan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\forms\models.py", line 436, in _save_m2m
    f.save_form_data(self.instance, cleaned_data[f.name])
  File "C:\Users\Nurzhan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\models\fields\related.py", line 1573, in save_form_data
    getattr(instance, self.attname).set(data)
  File "C:\Users\Nurzhan\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\models\fields\related_descriptors.py", line 928, in set
    objs = tuple(objs)
TypeError: 'Function' object is not iterable

What is `all_functions` which you pass to the `RequirementForm` constructor in the view? — user2390182, May 13 '17 at 17:19
I create queryset (all_functions) in view and then send it to form. This constructor works fine. I show in `function` field list of function objects. I just didnt add that part where I create `all_functions` cause I thought its not important. — Nurzhan Nogerbek, May 13 '17 at 17:51
My function field is ManyToManyField. But in form user can add only one object (in my cause one function). Maybe problem because of that? — Nurzhan Nogerbek, May 13 '17 at 18:05
I add to my post part where I creare `all_functions` and `all_programs`. Can you check it? — Nurzhan Nogerbek, May 13 '17 at 18:31

score 0 · Answer 1 · answered May 14 '17 at 05:30

Well my problem was that I tried to save one object to ManyToManyField by ModelChoiceField. ManyToManyField expect queryset. I decided to take data from form fields and save them in view by this code:

views.py:

function= requirement_form.cleaned_data['function']
programs = requirement_form.cleaned_data['programs']

requirement= requirement_form.save(commit=False)

requirement.function.add(function)
for program in programs:
    requirement.program.add(program)

Problems with save ManyToMany field data

1 Answers1