NoneType' 对象没有属性 'name'

Question

我在 django 中使用 k 均值方法构建葡萄酒推荐系统。我在管理员中创建了集群模块并手动添加了 3 个集群。但是，当我尝试向登录用户推荐葡萄酒时，出现此错误。请您帮忙：

AttributeError at /reviews/recommendation/
'NoneType' object has no attribute 'name'

我遇到错误：

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

这里是 view.py 的代码

@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 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}
        )

这是suggestions.py的代码

from .models import Review, Wine, Cluster
from django.contrib.auth.models import User
from sklearn.cluster import KMeans
from scipy.sparse import dok_matrix, csr_matrix
import numpy as np

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 1

当您要在集群表中添加数据时，您需要插入您当前登录的用户名。例如，

1. jadianes、carlos 和 lluis
2. 用户名>，teus，yasset
3. ...