How does Django Know the Order to Render Form Fields?

Question

If I have a Django form such as:

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


        

Answer 1

With Django >= 1.7 your must modify ContactForm.base_fields as below:

from collections import OrderedDict

...

class ContactForm(forms.Form):
    ...

ContactForm.base_fields = OrderedDict(
    (k, ContactForm.base_fields[k])
    for k in ['your', 'field', 'in', 'order']
)

This trick is used in Django Admin PasswordChangeForm: Source on Github

Answer 2

It has to do with the meta class that is used in defining the form class. I think it keeps an internal list of the fields and if you insert into the middle of the list it might work. It has been a while since I looked at that code.

Answer 3

I've used this to move fields about:

def move_field_before(frm, field_name, before_name):
    fld = frm.fields.pop(field_name)
    pos = frm.fields.keys().index(before_name)
    frm.fields.insert(pos, field_name, fld)

This works in 1.5 and I'm reasonably sure it still works in more recent versions.

Answer 4

New to Django 1.9 is Form.field_order and Form.order_fields().

# forms.Form example
class SignupForm(forms.Form):

    password = ...
    email = ...
    username = ...

    field_order = ['username', 'email', 'password']


# forms.ModelForm example
class UserAccount(forms.ModelForm):

    custom_field = models.CharField(max_length=254)

    def Meta:
        model = User
        fields = ('username', 'email')

    field_order = ['username', 'custom_field', 'password']

Answer 5

Using fields in inner Meta class is what worked for me on Django==1.6.5:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
Example form declaration with custom field order.
"""

from django import forms

from app.models import AppModel


class ExampleModelForm(forms.ModelForm):
    """
    An example model form for ``AppModel``.
    """
    field1 = forms.CharField()
    field2 = forms.CharField()

    class Meta:
        model = AppModel
        fields = ['field2', 'field1']

As simple as that.

Answer 6

Form fields have an attribute for creation order, called creation_counter. .fields attribute is a dictionary, so simple adding to dictionary and changing creation_counter attributes in all fields to reflect new ordering should suffice (never tried this, though).