Model.objects.get（）有效，但在使用ForeignKey属性时无效

Question

I have a profile model that looks like this:

class Profile(models.Model):
    username = models.ForeignKey(User, blank=True, null=True)
    age = models.IntegerField(default=0)
    points = models.IntegerField(default=100)

    def __str__(self):
        return str(self.username)

Here's my template

<h3><a href="{% url 'profile' u=i.user %}" class='username_foreign'>{{ i.user }}</a></h3>

which points to this url:

url(r'^profile/(?P<u>\w+)/', profile, name='profile')

and here's my view function:

def profile(request, u):
    if request.method == 'GET':
        profile = Profile.objects.get(username=u)

    return render(request, 'base.html', {})

As you can see here I pass through u which is the username. But when I try to get() the profile via the username passed through, I get this error:

ValueError at /profile/zorgan/

invalid literal for int() with base 10: 'zorgan'

However when I use get() on any other attribute of my Profile model, it works fine. And it even prints my username . So when I do this:

def profile(request, u):
    if request.method == 'GET':
        print(u) #prints username
        profile = Profile.objects.get(points=50)
        print(profile.username) #successfully prints username (same as 'u')

    return render(request, 'base.html', {})

As you can see above, getting the Profile object via its attribute doesn't work for username . And the problem isn't related to the u as that successfully prints aswell. Any idea what the problem is?

Answer 1

The field you've called username isn't a username at all. It's a ForeignKey, which is an integer value pointing at a row in another table. You should call it what it is: user .

To look up the actual username, in the User table, you need to use the double-underscore syntax. This would work:

profile = Profile.objects.get(username__username=u)

but as I said, you should really rename that username field, in which case you would do:

profile = Profile.objects.get(user__username=u)

Another way to do it would be to look up the User directly and then get the Profile:

user = User.objects.get(username=u)
profile = user.profile

but this takes two separate queries, rather than one joined one.