在没有 get_object_or_404() 的情况下查询模板/视图中的模型字段数据

Question

Homefeed 是我查询所有博文的页面

在这个项目中，任何看到他们感兴趣的博文的用户都可以将他们的兴趣提交给博文。 1 位用户只能对该博文提交 1 个兴趣，但他们可以向不同的博文提交任意数量的兴趣。

现在在我的 home.html 中，我正在尝试使如果您已提交对该特定博客文章的兴趣（也就是您的兴趣状态为待处理或接受或拒绝），您将看到查看兴趣按钮而不是提交兴趣按钮。

但我面临一个问题，因为在我看来，我查询的是blog_posts = BlogPost.objects.all() 而不是blog_post = get_object_or_404(BlogPost, slug=slug)。因此，我如何能够查询对于特定的博文，用户是否已经提交了对我的模板的兴趣以确定应该在我的 home.html 中显示哪个按钮？谢谢，我也不想更改网址:)

views.py

def home_feed_view(request, *args, **kwargs):
    context = {}
    blog_posts = BlogPost.objects.all()
    context['blog_posts'] = blog_posts 
    page = pageFilter(request.GET, queryset=BlogPost.objects.exclude(author_id=request.user.id).order_by('date_updated')) 
    context['page'] = page
    paginated_page = Paginator(page.qs, 4)
    page = request.GET.get('page')
    page_obj = paginated_page.get_page(page)

    context['page_obj'] = page_obj
    return render(request, "HomeFeed/snippets/home.html", context)

home.html

{% for post in page_obj %}

{% if post.interest_set.exists and request.user.is_authenticated %}

     <a class="btn btn-info btn-sm" href="{% url 'HomeFeed:submitinterest' post.slug %}">View Interest</a>
     {% else %}  
      <a class="btn btn-warning btn-sm" href="{% url 'HomeFeed:submitinterest' post.slug %}">Submit Interest</a>
      {% endif %}
      {% endfor %}

urls.py

path('', home_feed_view , name= "main"),

models.py

class Account(AbstractBaseUser):
 email                  = models.EmailField(verbose_name="email", max_length=60, unique=True)
 username               = models.CharField(max_length=30, unique=True)

class BlogPost(models.Model):
 title                  = models.CharField(max_length=50, null=False, blank=False, unique=True)
 author                     = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
 slug                   = models.SlugField(blank=True, unique=True)

class Interest(models.Model):
   user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
   blog_post = models.ForeignKey(BlogPost, on_delete=models.CASCADE)

class InterestInvite(models.Model):

   ACCEPT = "ACCEPT"
   DECLINE = "DECLINE"
   PENDING = "PENDING"
   STATUS_CHOICES = [
      (ACCEPT, "accept"),
      (DECLINE, "decline"),
      (PENDING, "pending"),

   ]

   interest = models.OneToOneField(Interest, on_delete=models.CASCADE, related_name="interest_invite")   
   status = models.CharField(max_length=25, choices=STATUS_CHOICES, default=PENDING)
   objects= models.Manager

views.py

        type = TypeFilter(request.GET, queryset=BlogPost.objects.exclude((Q(author_id__in=request.user.blocked_users.all()) | Q(author = request.user))).order_by('date_updated')).annotate(user_has_interest=Case(When(interest__user=request.user, then=Value(True)), default=False, output_field=BooleanField()))

使用 Django 过滤器： 过滤器.py

class TypeofIdeaFilter(django_filters.FilterSet):
    title = django_filters.CharFilter(field_name="title", lookup_expr='icontains')

    class Meta:
        model = BlogPost

Answer 1

您可以在查询中注释字段：

from django.db.models import Case, When, Value, BooleanField

blog_posts = BlogPost.objects.all().annotate(
    user_has_interest=Case(When(interest__user=request.user, then=Value(True)), default=False, output_field=BooleanField())
)

现在您可以使用 if-else 签入模板：

{% if post.user_has_interest %}
    Something
{% else %}
    Something else
{% endif %}

Answer 2

As Pierre mentioned 模板标签也实现了这一点（alternate for annotate Abdul 回答）。

首先创建文件结构。进入需要标签的app目录，添加以下文件：

templatetags
templatetags/__init__.py
templatetags/blog_tags.py

templatetags/blog_tags.py 文件：

from django import template

register = template.Library()

@register.simple_tag
def interest_submitted(blog_id, user_id):
    if Interest.objects.filter(blog_post__id=blog_id, user_id=user_id).exists():
        return True
    else:
        return False

在模板中：

{% load blog_tags %} <!--don't forget to load the blog_tags.py file in the template. -->

{% for post in page_obj %}
{% interest_submitted post.id request.user.id as result %}
{% if result and request.user.is_authenticated %}
    <a class="btn btn-info btn-sm" href="{% url 'HomeFeed:submitinterest' post.slug %}">View Interest</a>
{% else %}  
    <a class="btn btn-warning btn-sm" href="{% url 'HomeFeed:submitinterest' post.slug %}">Submit Interest</a>
{% endif %}
{% endfor %}

Answer 3

您可以使用 try 代替 get_object_or_404()。这样，如果对象不存在，您可以使用不同的逻辑并返回不同的上下文

伪代码：

context = {}
    try:
       blog_posts = BlogPost.objects.all()
       ...
       context = "Something"
       return render(request, "HomeFeed/snippets/home.html", context)
    
    except BlogPost.DoesNotExist:
       context = "Something else"
       return render(request, "HomeFeed/snippets/home.html", context)