django：如何从CharField和ModelChoiceField获得价值

Question

I have a class GroupAdminForm which is used to extend the group admin page in Django. There are two fields, selected_to_change and print_name. What I am designing to do is to select a column in "selected_to_change" and enter a char name in "print_name" , in order to make a query like:

UPDATE "annotation" 
SET print_name= "value of print_name" 
WHERE id = "value of selected_to_change";

Here is the GroupAdminForm:

class GroupAdminForm(forms.ModelForm):
    users = forms.ModelMultipleChoiceField(queryset=User.objects.all(),
                                       widget=FilteredSelectMultiple('Users', False),
                                       required=False)

    select_to_change = forms.ModelChoiceField(queryset=Annotation.objects.all(), required=False)
    print_name = forms.CharField(required=False)

    class Meta:
        model = Group

    def __init__(self, *args, **kwargs):
        instance = kwargs.get('instance', None)
        if instance is not None:
            initial = kwargs.get('initial', {})
            initial['users'] = instance.user_set.all()
            initial['locations'] = instance.c_locations.all()
            kwargs['initial'] = initial
        super(GroupAdminForm, self).__init__(*args, **kwargs)

    def save(self, commit=True):
        group = super(GroupAdminForm, self).save(commit=commit)

        if commit:
            group.user_set = self.cleaned_data['users']
        else:
            old_save_m2m = self.save_m2m
            def new_save_m2m():
                old_save_m2m()
                group.user_set = self.cleaned_data['users']
            self.save_m2m = new_save_m2m
        return group

How can I get the values from the CharField and ModelChoiceField to make such queries in the method save()? Thanks.

Answer 1

You are already using data from the saved form in self.cleaned_data.

print self.cleaned_data['select_to_change']
print self.cleaned_data['print_name']