Is this not a tuple?

问题

I can't figure out what I'm doing wrong here. My error is: ImproperlyConfigured at /admin/ 'CategoryAdmin.fields' must be a list or tuple.

Isn't the CategoryAdmin.fields a tuple? Am I reading this wrong?

admin.py ..

class CategoryAdmin(admin.ModelAdmin):
    fields = ('title')
    list_display = ('id', 'title', 'creation_date')

class PostAdmin(admin.ModelAdmin):
    fields = ('author', 'title', 'content')
    list_display = ('id', 'title', 'creation_date')

admin.site.register(
    models.Category, 
    CategoryAdmin
)
admin.site.register(
    models.Post, 
    PostAdmin
)

回答1:

No, it is not. You need to add a comma:

fields = ('title',)

It is the comma that makes this a tuple. The parenthesis are really just optional here:

>>> ('title')
'title'
>>> 'title',
('title',)

The parenthesis are of course still a good idea, with parenthesis tuples are easier to spot visually, and the parenthesis distinguish the tuple in a function call from other parameters (foo(('title',), 'bar') is different from foo('title', 'bar')).

回答2:

It should be:

fields = ('title', )

Example:

In [64]: type(('title'))
Out[64]: str

In [65]: type(('title', ))
Out[65]: tuple

回答3:

You need a comma after title:

fields = ('title',)

回答4:

Replace it with this:

fields = ('title', )

来源：https://stackoverflow.com/questions/15412055/is-this-not-a-tuple