how to check the username before registering?

please help to write the test.

views.py:

def ajax_username_check(request):
    """
    ajax check username for registration form
    return true - no matched
    return false - matched
    """ 
    result = True   

    if request.method == 'POST' and request.is_ajax():
        username = request.POST.get('username', '')
        try:
            check_username_match = User.objects.get(username=username)
        except:
            pass
        else:
            result = False

    data = {
        'result': result,       
    }

    return HttpResponse(json.dumps(data), content_type='application/json')

tests.py:

class TestAjaxCheckUsername(TestCase):
    def setUp(self):
        self.client = Client()
        self.record = User.objects.create(
            user_id=2, 
            username='qqqqqq', 
            password='pbkdf2_sha256$12000$Bm1GmmeGtnyU$v4E1UUcXWjk7pmQEkIWXvY2Hsw2ycG783R/bVpoVEWk=', 
            is_active=1, 
            is_staff=0,
            is_superuser=0,
            email='asasas@mail.ru'
        )

    def test_diary(self):  
        json_string = json.dumps({'username':'qqqqqq'})  

        self.response = self.client.post('/ajax_username_check/', json_string, "text/json", HTTP_X_REQUESTED_WITH='XMLHttpRequest')
        self.assertContains(self.response, true)

error message:

ERROR: test_diary (app_accounts.tests.TestAjaxCheckUsername)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/kalinins/.virtualenvs/kinopom_project/kinopom/app_accounts/tests.py", line 17, in setUp
    email='asasas@mail.ru'
  File "/home/kalinins/.virtualenvs/kinopom_project/kinopom_env/local/lib/python2.7/site-packages/django/db/models/manager.py", line 157, in create
    return self.get_queryset().create(**kwargs)
  File "/home/kalinins/.virtualenvs/kinopom_project/kinopom_env/local/lib/python2.7/site-packages/django/db/models/query.py", line 320, in create
    obj = self.model(**kwargs)
  File "/home/kalinins/.virtualenvs/kinopom_project/kinopom_env/local/lib/python2.7/site-packages/django/db/models/base.py", line 417, in __init__
    raise TypeError("'%s' is an invalid keyword argument for this function" % list(kwargs)[0])
TypeError: 'user_id' is an invalid keyword argument for this function

I am trying to verify the existence of a user named qqqqqq using Ajax-request. I need to check the return value for the function ajax_username_check()

I have read this post and tried to use it, but to no avail

Solution

User has no field user_id, it has a field id. However, I wouldn't set that either, as the ID may already exist and usually Django chooses the model ids. So I would just remove the user_id=2 line.

Two other comments: first, never use a bare except: like that, use except User.DoesNotExist: explicitly, otherwise you might accidentally catch who knows what exception.

Second, I wouldn't use get() here at all: what you're looking for is whether the User exists or not. So:

result = {'result': User.objects.filter(username=username).exists()}

should do.