How to show an update form while keeping the original data in Django?

Question

I'm using Django Forms to do some updating work. For example, I write a FilmForm to present a film information form:

class FilmForm(forms.Form):
    name = forms.CharField()
    director = forms.CharField()
    release_year = forms.DateField()
    ......(many other infos)

And I create and save a model instance using the form. Next time I want to modify only one info, like 'director', and update the model info using the FilmForm .

def FilmUpdate(request,pk):
    if request.method == 'POST':
        ...
    else:
        form = FilmForm()
        return render(request,'film_update.html', {'form':form})

but when the form show up, the html inputs are all blank,and have to input all the original data again while the only item I want modify is just 'director'. So how to present the update form with the original data keeping?

Answer 1

def FilmUpdate(request,pk):
    instance = Film.objects.get(id=pk)
    if request.method == 'POST':
        form = FilmForm(instance=instance, data=request.POST, files=request.FILES)
        ...
    else:
        form = FilmForm(instance=instance)
        return render(request,'film_update.html', {'form':form})

you should pass instance arg to FilmForm