用 ModelChoiceField 替换多对多关系

Question

我无法尝试将多对多关系呈现为 ModelChoiceField 而不是 ModelMultipleChoiceField。所以我尝试了以下（简化）：

models.py:

class Project(models.Model):
    name = models.CharField(max_length=20, unique=True)
    manager = models.ManyToManyField(User, related_name="manager_related")

forms.py:

class ProjectForm(forms.ModelForm):
    manager = forms.ModelChoiceField(queryset=User.objects.all(),
                               empty_label='Choose Manager', required=False)

    class Meta:
        model = Project
        fields = ['name', 'manager']

表单正确呈现，我可以 select 列表中的注册用户。但是在提交表单后，我会收到 TypeError 消息 'User' object is not iterable。我认为 save() 函数需要两个值来保存多对多关系，但 ModelChoiceField returns 只需要一个。我不知道如何解决...

Answer 1

您可以通过更改小部件来处理此问题：

forms.py:

class ProjectForm(forms.ModelForm):
    class Meta:
        model = Project
        fields = ['name', 'manager']
        widgets = {
            'manager': forms.Select(),
        }

Select widget is the default widget for ModelChoiceField 并且 Django 适当地呈现它：

ModelChoiceField

class ModelChoiceField(**kwargs)

Default widget: Select

或者您可以使用 SelectMultiple and CheckboxSelectMultiple。

Answer 2

经过一番摸索，我得到了一个可行的解决方案。 Wtowers 提案无效。为什么？阅读那个：

所以我们必须自己处理所有事情。

forms.py

# helper class: returning full_name instead of username
class UserModelChoiceField(forms.ModelChoiceField):
    def label_from_instance(self, obj):
        return obj.get_full_name()


class ProjectForm(forms.ModelForm):
    manager = UserModelChoiceField(queryset=User.objects.all(), label='Manager', required=True)

    class Meta:
        model = Project
        fields = ['name']

views.py

if request.method == 'POST':
    form = ProjectForm(request.POST)
    if form.is_valid():
        # get cleaned data from form
        prj_name = form.cleaned_data['name']
        prj_manager = form.cleaned_data['manager']  # this is a User-object

        # generate project and store it to db
        prj = Project(name=prj_name)
        prj.save()

        # handling now m2m relation for manager
        prj.manager.add(prj_manager)

        return HttpResponseRedirect("/project/list")

else:
    form = ProjectForm()

用 ModelChoiceField 替换多对多关系

Replacing ManyToMany-Relation with ModelChoiceField

python

django

django-models

django-forms