我的django查询:如何提高列表视图的速度

Question

列表页面是分页的，只显示10个期刊帖子。尽管如此，仍有95个查询正在执行。这会影响页面加载速度。而不是加载<1秒，它需要大约4-5秒。这是我的代码，请检查并让我知道如何优化。views.py

class PostListView(LoginRequiredMixin,ListView):
    model = Post
    paginate_by = 10

    def get_queryset(self):
        qs = super(PostListView, self).get_queryset().filter(Q(
            Q(language_id__in=self.request.user.native_language),
            ~Q(user_id__in=self.request.user.forbidden_user_list))).order_by('-created')
        return qs

    def get_context_data(self, **kwargs):
        context = super(PostListView, self).get_context_data(**kwargs)
        context['list_type'] = 'all'

models.py

class Post(models.Model):
    user = models.ForeignKey(to=settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    title = models.CharField(max_length=60)
    text = models.TextField()
    native_text = models.TextField(blank=True)
    created = models.DateTimeField(default=timezone.now, db_index=True)
    # updated = models.DateTimeField(auto_now=True)
    # is_corrected = models.BooleanField(default=False)
    users_like = models.ManyToManyField(settings.AUTH_USER_MODEL, related_name='posts_liked',
                                        blank=True)
    language = models.ForeignKey('account.Language', on_delete=models.SET_NULL, null=True)

    def __str__(self):
        return self.text

    def get_absolute_url(self):
        return reverse('post-detail', args=[str(self.id)])

    @property
    def get_correctors(self):
        from account.models import Profile as User
        result = list(set(User.objects.all().filter((Q(correctedrows__post_id=self.id) | Q(perfectrows__post_id=self.id) | Q(comment__post_id=self.id)))))
        return result

Answer 1

在您的get_queryset方法中，您应该尝试使用select_related和prefetch_related来获取将在模板中使用的内容。

例如，如果在您的模板中执行post.user.name，这将导致额外的查询。尝试如下所示：

def get_queryset(self):
        qs = super(PostListView, self).get_queryset().select_related('user', 'language'). prefetch_related('users_like').filter(Q(
            Q(language_id__in=self.request.user.native_language),
            ~Q(user_id__in=self.request.user.forbidden_user_list))).order_by('-created')
        return qs