CODEWITHSUNDEEP
djangopython-3.xdjango-modelsdjango-admin
Nagesh Mhapadi
Nagesh Mhapadi

Reputation: 152

overriding empty_value_display for specified field not working in django Admin

I have written a model as follows:

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)
    title = models.CharField(max_length=3)
    birth_date = models.DateField(blank=True, null=True)

And my modeladmin is as follows:

from django.contrib import admin

class AuthorAdmin(admin.ModelAdmin):
    fields = ('name', 'title', 'view_birth_date')

    def view_birth_date(self, obj):
        return obj.birth_date

    view_birth_date.empty_value_display = '-empty-'

As documented in django 2.1 https://docs.djangoproject.com/en/2.1/ref/contrib/admin/#django.contrib.admin.ModelAdmin.empty_value_display, I am trying to do this but its not working.

Its gives me fielderror. Even I didn't understand its purpose. My traceback:

Traceback (most recent call last):
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\contrib\admin\options.py", line 703, in get_form
return modelform_factory(self.model, **defaults)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\forms\models.py", line 551, in modelform_factory
return type(form)(class_name, (form,), form_class_attrs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\forms\models.py", line 266, in __new__
raise FieldError(message)
django.core.exceptions.FieldError: Unknown field(s) (view_birth_date) specified for Author
During handling of the above exception, another exception occurred: 
Traceback (most recent call last):
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\core\handlers\exception.py", line 34, in inner
response = get_response(request)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\core\handlers\base.py", line 126, in _get_response
response = self.process_exception_by_middleware(e, request)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\core\handlers\base.py", line 124, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\contrib\admin\options.py", line 604, in wrapper
return self.admin_site.admin_view(view)(*args, **kwargs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\utils\decorators.py", line 142, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\views\decorators\cache.py", line 44, in _wrapped_view_func
response = view_func(request, *args, **kwargs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\contrib\admin\sites.py", line 223, in inner
return view(request, *args, **kwargs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\contrib\admin\options.py", line 1639, in change_view
return self.changeform_view(request, object_id, form_url, extra_context)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\utils\decorators.py", line 45, in _wrapper
return bound_method(*args, **kwargs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\utils\decorators.py", line 142, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\contrib\admin\options.py", line 1525, in changeform_view
return self._changeform_view(request, object_id, form_url, extra_context)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\contrib\admin\options.py", line 1554, in _changeform_view
ModelForm = self.get_form(request, obj, change=not add)
File "C:\Users\monikat\Envs\django_training\lib\site-packages\django\contrib\admin\options.py", line 707, in get_form % (e, self.__class__.__name__)
django.core.exceptions.FieldError: Unknown field(s) (view_birth_date) specified for Author. Check fields/fieldsets/exclude attributes of class AuthorAdmin.

Does anyone know why this error is coming?

Upvotes: 0

Views: 1687

Answers (1)

not2acoder
not2acoder

Reputation: 1152

The problem is that you have defined view_birth_date in the fields attribute of model admin class.

Since it is not present in your db model, it is giving error. Such custom fields will work for list_display, in which you can fetch the value from a method as you have done above, see the docs.

Now if you want some custom field to display on the add/change page , you have to create a custom form and there you can define your custom fields. If the custom field is just for representation , you can define it as readonly as :

class AuthorAdmin(admin.ModelAdmin):
    fields = ('name', 'title', 'view_birth_date')
    readonly_fields = ['view_birth_date']

    def view_birth_date(self, obj):
        return obj.title

    view_birth_date.empty_value_display = '-empty-'

Hope it helps!

Upvotes: 1

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