我的 django 查询：如何提高列表查看速度

Question

List page is paginated and displaying only 10 journal posts. Despite this, there are 95 queries being performed. It's affecting the page load speed. Instead of loading <1 second it's taking around 4-5 seconds. Here are my code, please check and let me know how to optimize. 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

In your get_queryset method, you should try to use select_related and prefetch_related to get whatever you will use in your template.

For example, if in your template you are doing post.user.name , that is going to cause an additional query. Try something like this:

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