Using CKEditor with Flatpages

admin.py

from django.contrib import admin
from django.contrib.flatpages.models import FlatPage

# Note: we are renaming the original Admin and Form as we import them!
from django.contrib.flatpages.admin import FlatPageAdmin as FlatPageAdminOld
from django.contrib.flatpages.admin import FlatpageForm as FlatpageFormOld

from django import forms
from ckeditor.widgets import CKEditorWidget

class FlatpageForm(FlatpageFormOld):
    content = forms.CharField(widget=CKEditorWidget())
    class Meta:
        model = FlatPage # this is not automatically inherited from FlatpageFormOld
        fields = '__all__'


class FlatPageAdmin(FlatPageAdminOld):
    form = FlatpageForm


# We have to unregister the normal admin, and then reregister ours
admin.site.unregister(FlatPage)
admin.site.register(FlatPage, FlatPageAdmin)

In order to make it work with latest versions of Django you should add

class Meta:
    fields = '__all__'

Use with ckeditor https://django-ckeditor.readthedocs.io/en/latest/index.html#installation