Correspondence of the event that the result of form.is_valid () is always False in Django2 system

Events and environment

Event

** is_valid ** was executed by the ** post ** method of ** View ** class written in ** views.py **. The result of ** is_valid ** is ** False ** no matter what input is made on the web browser.

The validation method is not implemented in forms.py.

The following is an excerpt of the source code. There is a ** Meta ** class in the ** Form ** class, but this is a recognition that has nothing to do with this event.

views.py

class View(View):
    def post(self, request, *args, **kwargs):
        form = Form()
        is_valid = form.is_valid()
        print(is_valid)
        ...

forms.py

class Form(forms.ModelForm):
    class Meta:
        model = ExperimentResult
        fields = ("title", "comment",)
        widgets = {
            'title' : forms.TextInput(attrs={'class':'text_area'}),
            'comment' : forms.TextInput(attrs={'class':'text_area'})
        }

environment

The execution environment is ** django2.2.12 **, python3.7, Windows10.

• It is assumed that the OS and python version are irrelevant.

Cause

When instantiating the Form class, it is assumed that there is a "request" in the first argument of the init method.

When writing form = FormClass (), "request" is not passed to the init method. Therefore, when the "is_valid" method is executed, a validation error occurs because "request" is not passed, and False is always returned.

Correspondence

Insert data = request.POST as an argument when instantiating the Form class.

• In the case of GET method, it is assumed to be request.GET.

views.py

class View(View):
    def post(self, request, *args, **kwargs):
        form = Form(data=request.POST)
        is_valid = form.is_valid()
        print(is_valid)
        ...

After taking the above actions, I confirmed that True would return.

reference

https://stackoverflow.com/questions/20801452/django-form-is-valid-always-false