Django-form_valid()与save() [英] Django - form_valid() vs save()

问题描述

在Django表单中，为了保存其他数据，我通常使用 form_valid()，但由于我也可以使用formclass的 save()方法.

In django forms, for saving other data I usually use form_valid() but as I can also use save() method of formclass.

今天，我覆盖了 save()而不是 form_valid()，我的manytomanyfield遇到了问题.

Today I overrided save() instead of form_valid() and I got problem with my manytomanyfield.

使用时，不会保存manytomanyfield的值，但是当我使用 form_valid()时，它们开始保存.谁能告诉我两者的原因和不同之处，哪一种是最方便的方法?在什么情况下?

When using , the values of manytomanyfield are not saved but when I use form_valid() they start saving. Can anybody tell me the reason and what are the differences between both, which is the most convenient method and in what situation?

这是我对save()方法的重载:

Here is my overriding of save() method:

class ProductCreateForm(forms.ModelForm):
    sizes = make_ajax_field(ProductCreateModel,'sizes','sizes')
    colours = make_ajax_field(ProductCreateModel,'colours','colours')

    class Meta:
        model = ProductCreateModel

        fields = ('title','category',
                    'regions',)

    def __init__(self,*args,**kwargs):
        self.request = kwargs.pop("request")
        super(ProductCreateForm, self).__init__(*args, **kwargs)

    def save(self):
        product = super(ProductCreateForm, self).save(commit=False)
        user =  self.request.user

        product.location = user.user_location
        product.save()
        return product

当我重写form_valid()方法时:

When I override form_valid() method:

   def get_form_kwargs(self):
       kwargs = super(ProductCreateView,self).get_form_kwargs()
       kwargs.update({'request':self.request})
       return kwargs

   def form_valid(self, form):
       product = form.save(commit=False)
       user =  self.request.user
       form.instance.user = user
       form.instance.location = user.user_location
       form.save()
       return super(ProductCreateView, self).form_valid(form)

sizes ， colours 和 regions 是m2m字段，正如我在覆盖 save()值时提到的那样的m2m无法保存，但是当我覆盖 form_valid 时，它们开始保存.

sizes,colours and regions are m2m fields, as I mentioned when I overrides save() values of m2m not get saved but when I overrides form_valid they start saving.

推荐答案

如果使用 commit = False 保存表单，则必须调用表单的 save_m2m 方法进行保存多对多数据.有关更多信息，请参见文档.

If you save a form with commit=False, you must call the form's save_m2m method to save the many-to-many data. See the docs for more info.

如果您决定使用 form_valid 方法，我将更改以下内容:

If you decide to use the form_valid method, I would change the following things:

• 更新由 form.save()返回的实例并保存它，而不是再次调用 form.save().
• 明确调用 form.save_m2m()
• 返回重定向响应，而不是调用 super().form_valid()(这将再次保存表单)

• update the instance returned by form.save() and save it, instead of calling form.save() again.
• explicitly call form.save_m2m()
• return a redirect response instead of calling super().form_valid() (which will save the form again)

将它们放在一起，您将得到:

Putting that together, you get:

def form_valid(self, form):
    product = form.save(commit=False)
    product.user =  self.request.user
    product.location.location = user.user_location
    product.save()
    form.save_m2m()
    return redirect('/success-url/')

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