Writing custom admin form classes
Admin forms can be created and used just like the standard form classes we discussed in Chapter 5, Django Forms. For admin form classes, we need to use the Django ModelForm class instead of the standard Form class found in the django.forms library, because the fields in these forms will link to model classes. Refer to the examples found in Chapter 5, Django Forms, to learn more about how to customize and change your form class behavior, for either a Form or ModelForm class. Here, we will demonstrate just initializing your admin forms and enabling all fields that exist, to allow any of the engine change and add view pages to load without the errors mentioned earlier.
Initializing an admin form
If you have not already done so, in the chapter_6 app folder, create a file called forms.py. We need to create the three different form classes used in the previous examples of this chapter and call them EngineForm, AddEngineForm, and EngineSuperUserForm...