Pre-Setting django form data before displaying the form - django

Question

I am displaying a django form and I want to prepare some field data before it
is passed to to be rendered. In the django docs, I see plenty of places
where form data is accessed, but none where form data is set before display.
Any thoughts or suggestions on how to do this?
Here's an example similar to the django docs.
-----------forms.py--------------
class BookForm(ModelForm):
author = forms.CharField(max_length=100)
title = forms.CharField(max_length=3,
widget=forms.Select(choices=TITLE_CHOICES))
birth_date = forms.DateField(required=False)
-----------views.py--------------
def author_view(request):
if request.method == 'POST':
# DO My processing...
form = BookForm()
# How can I edit, or preset my form fields here?
c = Context({
'form': form,
})
return prepCxt(request, 'book.html', c) # Wrapper for easy display

Answer 1

In your views you have:
def author_view(request):
if request.method == 'POST':
# DO My processing...
form = BookForm()
# How can I edit, or preset my form fields here?
c = Context({
'form': form,
})
return prepCxt(request, 'book.html', c) # Wrapper for easy display
You should move your form=BookForm() before the if:
def author_view(request):
form = BookForm()
if request.method == 'POST':
# DO My processing...
What happens is that the if "POST" section adds a value in form and then it could get overriden.
Secondly if you are trying to change something in the way it display you are probably best adding default/initial values:
Django set default form values:
BookForm(initial={ 'myfield': 'myval'})
if you are tryiong to change values that you want to save to the DB then you:
if form.is_valid():
myobject = form.save(commit=false)
myobject.myfield = mval
myobj.save()
form = BookForm(instance = myobjext)
Something else? Please be more specific.