'NoneType' Objekt hat kein Attribut 'Name'

Question

Ich versuche ein Empfehlungssystem für Wein zu bauen. In reviews/view.py Seite habe ich diesen Fehler:

'NoneType' object has no attribute 'name' 

Dies war die Linie, wo ich diese Fehlermeldung anzeigt ist

User.objects.get(username=request.user.username).cluster_set.first().name 

der komplette Code:

from django.shortcuts import get_object_or_404, render 
from django.http import HttpResponseRedirect 
from django.core.urlresolvers import reverse 
from django.contrib.auth.models import User 
from .models import Review, Wine, Cluster 
from .forms import ReviewForm 
from .suggestions import update_clusters 

import datetime 

from django.contrib.auth.decorators import login_required 


def review_list(request): 
    latest_review_list = Review.objects.order_by('-pub_date')[:9] 
    context = {'latest_review_list': latest_review_list} 
    return render(request, 'reviews/review_list.html', context) 


def review_detail(request, review_id): 
    review = get_object_or_404(Review, pk=review_id) 
    return render(request, 'reviews/review_detail.html', {'review': review}) 


def wine_list(request): 
    wine_list = Wine.objects.order_by('-name') 
    context = {'wine_list': wine_list} 
    return render(request, 'reviews/wine_list.html', context) 


def wine_detail(request, wine_id): 
    wine = get_object_or_404(Wine, pk=wine_id) 
    form = ReviewForm() 
    return render(request, 'reviews/wine_detail.html', {'wine': wine, 'form': form}) 


@login_required 
def add_review(request, wine_id): 
    wine = get_object_or_404(Wine, pk=wine_id) 
    form = ReviewForm(request.POST) 
    if form.is_valid(): 
     rating = form.cleaned_data['rating'] 
     comment = form.cleaned_data['comment'] 
     user_name = request.user.username 
     review = Review() 
     review.wine = wine 
     review.user_name = user_name 
     review.rating = rating 
     review.comment = comment 
     review.pub_date = datetime.datetime.now() 
     review.save() 
     update_clusters() 
     # Always return an HttpResponseRedirect after successfully dealing 
     # with POST data. This prevents data from being posted twice if a 
     # user hits the Back button. 
     return HttpResponseRedirect(reverse('reviews:wine_detail', args=(wine.id,))) 

    return render(request, 'reviews/wine_detail.html', {'wine': wine, 'form': form}) 


def user_review_list(request, username=None): 
    if not username: 
     username = request.user.username 
    latest_review_list = Review.objects.filter(user_name=username).order_by('-pub_date') 
    context = {'latest_review_list': latest_review_list, 'username': username} 
    return render(request, 'reviews/user_review_list.html', context) 


@login_required 
def user_recommendation_list(request): 
    # get request user reviewed wines 
    user_reviews = Review.objects.filter(user_name=request.user.username).prefetch_related('wine') 
    user_reviews_wine_ids = set(map(lambda x: x.wine.id, user_reviews)) 

    # get request user cluster name (just the first one righ now) 
    try: 
     user_cluster_name = \ 
      User.objects.get(username=request.user.username).cluster_set.first().name 
    except: # if no cluster has been assigned for a user, update clusters 
     update_clusters() 
     user_cluster_name = \ 
      User.objects.get(username=request.user.username).cluster_set.first().name 

    # get usernames for other memebers of the cluster 
    user_cluster_other_members = \ 
     Cluster.objects.get(name=user_cluster_name).users \ 
      .exclude(username=request.user.username).all() 
    other_members_usernames = set(map(lambda x: x.username, user_cluster_other_members)) 

    # get reviews by those users, excluding wines reviewed by the request user 
    other_users_reviews = \ 
     Review.objects.filter(user_name__in=other_members_usernames) \ 
      .exclude(wine__id__in=user_reviews_wine_ids) 
    other_users_reviews_wine_ids = set(map(lambda x: x.wine.id, other_users_reviews)) 

    # then get a wine list including the previous IDs, order by rating 
    wine_list = sorted(
     list(Wine.objects.filter(id__in=other_users_reviews_wine_ids)), 
     key=lambda x: x.average_rating, 
     reverse=True 
    ) 

    return render(
     request, 
     'reviews/user_recommendation_list.html', 
     {'username': request.user.username, 'wine_list': wine_list} 
    ) 

Answer 1

Höchstwahrscheinlich wird der Code in Ihrem update_clusters Methode erstellt den Cluster für den Benutzer nicht. Stellen Sie sicher, dass Sie tatsächlich ein Cluster-Objekt für den jeweiligen Benutzer erstellen. Wenn Sie noch Zweifel haben, erwähnen Sie auch den Code dieser Funktion.

Answer 2

hier ist der Code für update_cluster()

def update_clusters(): 
    num_reviews = Review.objects.count() 
    update_step = ((num_reviews/100) + 1) * 5 
    if num_reviews % update_step == 0: # using some magic numbers here, sorry... 
     # Create a sparse matrix from user reviews 
     all_user_names = map(lambda x: x.username, User.objects.only("username")) 
     all_wine_ids = set(map(lambda x: x.wine.id, Review.objects.only("wine"))) 
     num_users = len(all_user_names) 
     ratings_m = dok_matrix((num_users, max(all_wine_ids) + 1), dtype=np.float32) 
     for i in range(num_users): # each user corresponds to a row, in the order of all_user_names 
      user_reviews = Review.objects.filter(user_name=all_user_names[i]) 
      for user_review in user_reviews: 
       ratings_m[i, user_review.wine.id] = user_review.rating 

     # Perform kmeans clustering 
     k = int(num_users/10) + 2 
     kmeans = KMeans(n_clusters=k) 
     clustering = kmeans.fit(ratings_m.tocsr()) 

     # Update clusters 
     Cluster.objects.all().delete() 
     new_clusters = {i: Cluster(name=i) for i in range(k)} 
     for cluster in new_clusters.values(): # clusters need to be saved before refering to users 
      cluster.save() 
     for i, cluster_label in enumerate(clustering.labels_): 
      new_clusters[cluster_label].users.add(User.objects.get(username=all_user_names[i])) 

Answer 3

Die cluster_set leer ist. Sie sollten überprüfen, dass die Variable nicht gleich None ist, bevor Sie versuchen, sie zu verwenden.