Correct way to override django admin's add_view()

Question

I need to override the view add_view() in django admin that gets called whenever I try to add a new model instance.

What I've tried:

class BaseMarketModelAdmin(admin.ModelAdmin):
    def save_model(self, request, obj, form, change):
        obj.creator = request.user
        return super().save_model(request, obj, form, change)

    def add_view(self, request, form_url='', extra_context=None):
        try:
            super(BaseMarketModelAdmin, self).add_view(
                request, form_url, extra_context
            )
        except ValidationError as e:
            return handle_exception(self, request, e)

    def change_view(self, request, object_id, form_url='', extra_context=None):
        try:
            return super(BaseMarketModelAdmin, self).change_view(
                request, object_id, form_url, extra_context
            )
        except ValidationError as e:
            return handle_exception(self, request, e)

The change_view() works without any problems, but when I try to add a new model instance using "Add ModelName" button in django admin I always get this exception:

AttributeError at /admin/market/exchange/add/
'NoneType' object has no attribute 'has_header'
Request Method: GET
Request URL:    http://127.0.0.1:8000/admin/market/exchange/add/
Django Version: 3.0.3
Exception Type: AttributeError
Exception Value:    
'NoneType' object has no attribute 'has_header'
Exception Location: /usr/local/lib/python3.7/site-packages/django/utils/cache.py in patch_response_headers, line 243
Python Executable:  /usr/local/bin/python
Python Version: 3.7.7

I tried checking the source code of django's add_view() which is placed in: django/contrib/admin/options.py and it seems that it only calls change_view() with no object_id. Then I tried this:

def add_view(self, request, form_url='', extra_context=None):
    return self.changeform_view(request, None, form_url, extra_context)

And it loads the new instance page correctly but does NOT call my BaseMarketModelAdmin.change_view() view!

Then I tried this:

def add_view(self, request, form_url='', extra_context=None):
    return BaseMarketModelAdmin.changeform_view(request, None, form_url, extra_context)

But it results in this exception:

AttributeError at /admin/market/exchange/add/
'NoneType' object has no attribute 'COOKIES'
Request Method: GET
Request URL:    http://127.0.0.1:8000/admin/market/exchange/add/
Django Version: 3.0.3
Exception Type: AttributeError
Exception Value:    
'NoneType' object has no attribute 'COOKIES'
Exception Location: /usr/local/lib/python3.7/site-packages/django/middleware/csrf.py in _get_token, line 170
Python Executable:  /usr/local/bin/python
Python Version: 3.7.7

Now I need to override that add_view() view. What is the correct way to do this?

Answer 1

It is missing the return value in the add_view method

    def add_view(self, request, form_url='', extra_context=None):
    try:
        return super(BaseMarketModelAdmin, self).add_view(
            request, form_url, extra_context
        )
    except ValidationError as e:
        return handle_exception(self, request, e)