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如何使forloops只在django python中通过唯一的值运行

django-views django-models python-3.x django

0

Samir Tendulkar · 技术社区 · 7 年前

简介: 我有一个叫 event 有一把钥匙 post . 它的工作方式是: 例子用户创建了一个名为“日食”的帖子。任何数量的用户都可以基于该日志创建事件。所以如果有人上了那篇文章的详细页面。有个按钮叫 See all Events 他们可以看到所有主持日食活动的人。假设有5个帖子(关于滑雪、徒步旅行等不同主题),其中3个帖子有10个活动。2个岗位没有活动。在我的主页上,我有一个写事件的部分。在主页的事件部分,我想展示3个有事件而不是30个事件的帖子,我该怎么做呢?这样我就不会多次访问数据库了

下面是 VIEW

class EventView(ListView):
    model = Event
    template_name = 'home.html'    
    context_object_name = 'all_events' 

    def get_queryset(self): 
        for post in Post.objects.all():
             return post.event_post.all() #event_post is a related_name of post see models below

#This is incorrect it shows the post 30 times. 10 times for each event. I want to see only 3 posts. They can see the events when they click to open the post

我如何才能做到这一点:

我的 事件模型 是

class Event(models.Model):
        user = models.ForeignKey(User, related_name='host')
        post = models.ForeignKey(Post, related_name='event_post')
        price = models.DecimalField(max_digits=5, decimal_places=2)
        stock = models.IntegerField(validators=[MinValueValidator(1), MaxValueValidator(15)])
        initial_stock = models.IntegerField(validators=[MinValueValidator(1), MaxValueValidator(15)], default=1)
        date = models.DateField()
        time_from = models.TimeField()
        time_to = models.TimeField()
        available = models.BooleanField(default=True)
        note = models.CharField(max_length=350, blank=True, null=True)
        created = models.DateTimeField(auto_now_add=True)
        updated = models.DateTimeField(auto_now=True)

我的 POST模型 是

class Post(models.Model):
    user = models.ForeignKey(User, related_name='posts')
    group = models.ForeignKey(Group, related_name='posts')
    created_at = models.DateTimeField(auto_now=True)
    title = models.CharField(max_length=250, unique=True)
    slug = models.SlugField(allow_unicode=True, unique=True)
    message = models.TextField()
    message_html = models.TextField(editable=False)
    post_image = models.ImageField(upload_to='post_images/')

2 回复 | 直到 7 年前

1

Oh Great One 7 年前

Post.objects.all() selected_post.event_post_set.all()

PostView Post EventView

post = Post.objects.get(pk=passed_in_post_pk)
...
return post.event_post_set.all()

.exists() if

post_events_exist = post.event_post_set.all().exists()
if post_events_exist:
    # there is at least 1 event in the query set.

# Rename EventView --> PostView
# Inside of your now PostView
# All we need to do is return all your instances of Post
# and go to your post_template.html (shows the posts, you call it events)
return Post.objects.all()

# Inside of a new view called EventView
# We can get to this view by clicking one of the posts above.
# This assumes we send a parameter through url in template.
# This will send user to event_template.html (shows all events for that post)
post = Post.objects.get(pk=passed_in_post_pk)
return post.post_event_set.all()

<!-- assuming all_posts = Post.objects.all() -->
{% for post in all_posts %}
    {{ post.title }}
    <a href="{{ url_that_links_to_event_view post.pk }}">Info</a>
    <!-- this will send post.pk as a parameter to that view (so long as your accept a parameter in your urls.py for this link -->
{% endfor %}

{% for event in all_events %}
    {{ event.price }}
{% endfor %}

2

0

Samir Tendulkar 7 年前

for post in Post.objects.all():
    if post.event_post.exists():
        print.post.title: