different fields for add and change pages in admin

Question

I have a django app with the following class in my admin.py:

class SoftwareVersionAdmin(ModelAdmin):
    fields = (\"product\", \"version_number\", \"descrip         


        

Answer 1

I couldn't get this working in django 1.6.5 using the above solutions. So I tried creating forms and having get_form serve those pre-defined forms depending on if the object exists or not:

models.py:

from django.db import models

class Project(models.Model):
    name = models.CharField('Project Name', max_length=255)
    slug = models.SlugField('Project Slug', max_length=255, unique=True)

forms.py: from django import forms from models import Project

class ProjectAddForm(forms.ModelForm):

    test = forms.Field()

    class Meta:
        model = Project


class ProjectEditForm(forms.ModelForm):

    class Meta:
        model = Project
        fields = ("name", 'slug')

admin.py

from django.contrib import admin
from models import Project
from forms import ProjectAddForm, ProjectEditForm


class ProjectAdmin(admin.ModelAdmin):

    def get_form(self, request, obj=None, **kwargs):
        # Proper kwargs are form, fields, exclude, formfield_callback
        if obj:
            self.form = ProjectEditForm
        else:
            self.form = ProjectAddForm
        return super(ProjectAdmin, self).get_form(request, obj, **kwargs)


admin.site.register(Project, ProjectAdmin)

Now I can intercept the non-persistent test field in the forms clean and do as I wish with it, just overwrite clean in the ProjectAddForm:

def clean(self):
    cleaned_data = super(ProjectAddForm, self).clean()
    test = cleaned_data.get("test")
    # Do logic here
    #raise forms.ValidationError("Passwords don't match.")
    return cleaned_data

Answer 2

This is how it's done in Django 1.10. Just override get_form and return add_form when object is None:

class FoobarAddForm(forms.ModelForm):
    class Meta:
        model = Foobar
        fields = ['some_field',]

@register(Foobar)
class AdminFoobar(admin.ModelAdmin):
    add_form = FoobarAddForm

    def get_form(self, request, obj=None, **kwargs):
        defaults = {}
        if obj is None:
            defaults['form'] = self.add_form
        defaults.update(kwargs)
        return super(AdminFoobar, self).get_form(request, obj, **defaults)

Answer 3

First have a look at source of ModelAdmin class' get_form and get_formsets methods located in django.contrib.admin.options.py. You can override those methods and use kwargs to get the behavior you want. For example:

class SoftwareVersionAdmin(ModelAdmin):
    def get_form(self, request, obj=None, **kwargs):
        # Proper kwargs are form, fields, exclude, formfield_callback
        if obj: # obj is not None, so this is a change page
            kwargs['exclude'] = ['foo', 'bar',]
        else: # obj is None, so this is an add page
            kwargs['fields'] = ['foo',]
        return super(SoftwareVersionAdmin, self).get_form(request, obj, **kwargs)