Django ReadOnlyAdmin

@register.inclusion_tag('admin/submit_line.html', takes_context=True)
def submit_row(context):
    """
    Displays the row of buttons for delete and save.
    """
    ctx = original_submit_row(context)
    ctx.update({
        'show_save_and_add_another': context.get('show_save_and_add_another', ctx['show_save_and_add_another']),
        'show_save_and_continue': context.get('show_save_and_continue', ctx['show_save_and_continue']),
        'read_only': context.get('read_only', False)
    })
    return ctx


class ReadOnlyAdmin(admin.ModelAdmin):
    """
    Mixin to be used for customizing admin for Readonly access.
    1. change_view_readonly_fields - Makes fields editable in add view but readonly in edit view.
    2. Makes all fields/model fields readonly and user can not change anything in edit view.
    3. Hides the "Save And Add Another" & "Save And Continue" buttons.
    4. Make Readonly JSON fields pretty.

    TODO: Hide "Save" button as well from readonly view.
    This will require Django admin template override - "admin/submit_line.html".

    """

    change_view_readonly_fields = ()

    def __init__(self, model, admin_site):
        super(ReadOnlyAdmin, self).__init__(model, admin_site)

        # Store JSON fields of the model
        self._json_fields = tuple([f.name for f in self.model._meta.fields if isinstance(f, StrictJsonField)])

    @property
    def json_fields(self):
        return self._json_fields

    def user_is_readonly(self, request):
        """
        This method defines the readonly access. By default all users other than superuser gets readonly access
        but it can be customized at per ModelAdmin level.
        """
        return not request.user.is_superuser

    def get_form(self, request, obj=None, **kwargs):
        form = super(ReadOnlyAdmin, self).get_form(request, obj, **kwargs)

        # Remove json_fields from readonly and make them disabled instead.
        json_readonly_fields = tuple(set(self._get_all_readonly_fields(request, obj)) & set(self.json_fields))

        for field_name in json_readonly_fields:
            if field_name in form.base_fields:
                form.base_fields[field_name].widget = ReadOnlyTextAreaWidget(getattr(obj, field_name, ''))

        return form

    def _get_all_readonly_fields(self, request, obj=None):
        readonly_fields = self.readonly_fields

        if self.user_is_readonly(request):
            readonly_fields = self.fields or tuple([f.name for f in self.model._meta.fields])

        if obj:  # editing an existing object
            readonly_fields = readonly_fields + tuple(set(self.change_view_readonly_fields) - set(readonly_fields))

        return readonly_fields

    def get_readonly_fields(self, request, obj=None):

        # Remove json_fields from readonly and make them disabled instead.
        readonly_fields = tuple(set(self._get_all_readonly_fields(request, obj)) - set(self.json_fields))

        return readonly_fields

    def change_view(self, request, object_id, form_url='', extra_context=None):
        extra_context = self.update_context(request, extra_context)
        return super(ReadOnlyAdmin, self).change_view(request, object_id,
                                                      form_url, extra_context=extra_context)

    def add_view(self, request, form_url='', extra_context=None):
        extra_context = self.update_context(request, extra_context)
        return super(ReadOnlyAdmin, self).add_view(request,
                                                   form_url, extra_context=extra_context)

    def update_context(self, request, extra_context):
        extra_context = extra_context or {}
        extra_context['show_save_and_add_another'] = False
        extra_context['show_save_and_continue'] = False
        if self.user_is_readonly(request):
            extra_context['read_only'] = False
        return extra_context