Question

If I have a Django form such as:

class ContactForm(forms.Form):     subject = forms.CharField(max_length=100)     message = forms.CharField()     sender = forms.EmailField() 

And I call the as_table() method of an instance of this form, Django will render the fields as the same order as specified above.

My question is how does Django know the order that class variables where defined?

(Also how do I override this order, for example when I want to add a field from the classe’s init method?)

Answer 1

I went ahead and answered my own question. Here’s the answer for future reference:

In Django form.py does some dark magic using the __new__ method to load your class variables ultimately into self.fields in the order defined in the class. self.fields is a Django SortedDict instance (defined in datastructures.py).

So to override this, say in my example you wanted sender to come first but needed to add it in an init method, you would do:

class ContactForm(forms.Form):     subject = forms.CharField(max_length=100)     message = forms.CharField()     def __init__(self,*args,**kwargs):         forms.Form.__init__(self,*args,**kwargs)         #first argument, index is the position of the field you want it to come before         self.fields.insert(0,'sender',forms.EmailField(initial=str(time.time())))