Model.manytomanyfield.all() Gives Attributeerror: 'manytomanydescriptor' Object Has No Attribute 'all'

I'm using Django 2.0.2, Python 3.6.4 and PyCharm 2017.3.3 Models: (in models.py) class Position(models.Model): title = models.CharField(max_length=50) gang = models.Foreign

Solution 1:

Evaluating relationships are done with an instance that is an initialized instance of the class.

An instance of the Application.

application = Application.objects.first()
application.positions.all()

Change the form queryset after initialization.

classRankingForm(forms.ModelForm):
    rank = forms.IntegerField(max_value=3, min_value=1)
    position = forms.ModelMultipleChoiceField(queryset=Positions.objects.none())

    classMeta:
        model = Ranking
        exclude = ['applicant']
        fields = ['rank', 'position']

    def__init__(self, *args, **kwargs):
        super(RankingForm, self).__init__(*args, **kwargs)
        self.fields['rank'].widget.attrs.update({'class': 'form-control'})  
        self.fields['position'].queryset = self.instance.positions.all()

Solution 2:

You can access the current instance of your model that the ModelForm object is working with using the instance attribute. You can then use it to create the correct queryset in __init__:

classRankingForm(forms.ModelForm):
    ...

    def__init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields['rank'].widget.attrs.update({'class': 'form-control'})
        self.fields['position'].queryset = self.instance.positions.all()