问题描述
我有一个Django应用,用户可以在其中发布照片,并在照片下方发表其他评论。
留下评论时,我需要通知:
- 其他人谁在此线程中撰写
- 照片的所有者,以防不属于(1)
对于(1),我这样做:
#I切成25分,因为我任意认为超出此范围的任何人不相关的。
all_commenter_ids = PhotoComment.objects.filter(which_photo = which_photo).order_by('-id')。values_list('submitted_by',flat = True)[:25]
接下来,对于(2),我尝试:
all_relevant_ids = all_commenter_ids.append(which_photo.owner_id)
all_relevant_ids = list(set(all_relevant_ids))
我最终得到一个错误:
我发现这很奇怪,因为我正在提取 values_list 。
不是列表对象,在这种情况下,属性不应添加
场景?请解释问题所在,并提出其他建议。
values_list
方法返回 ValuesListQuerySet
。这意味着它具有查询集的优点。例如,它是惰性的,因此切片时仅从数据库中获取前25个元素。
要将其转换为列表,请使用 list()
。
all_commenter_ids = PhotoComment.objects.filter(which_photo = which_photo).order_by ('-id')。values_list('submitted_by',flat = True)[:25]
all_commenter_ids = list(all_commenter_ids)
您也许可以从 User
模型启动查询集,而不必使用 values_list
。您尚未显示模型,因此下面的代码是一个猜测:
from django.db.models import Q
评论者= User.objects.filter(Q(id = which_photo.owner_id)| Q(photocomment = which_photo))
I have a Django app where users post photos, and other leave comments under the photos.
When a comment is left, I need to notify:
- Everyone else who wrote in this thread
- The owner of the photo, in case they're not included in (1)
For (1), I do:
#I slice by 25 because I arbitrarily deem anyone beyond that irrelevant.
all_commenter_ids = PhotoComment.objects.filter(which_photo=which_photo).order_by('-id').values_list('submitted_by', flat=True)[:25]
Next, for (2), I try:
all_relevant_ids = all_commenter_ids.append(which_photo.owner_id)
all_relevant_ids = list(set(all_relevant_ids))
I end up with an error:
I find this strange, because I'm extracting a values_list.
Isn't that a list object, and in that case, shouldn't the attribute append
work in this scenario? Please explain what's wrong, and suggest alternatives.
The values_list
method returns a ValuesListQuerySet
. This means it has the advantages of a queryset. For example it is lazy, so you only fetch the first 25 elements from the database when you slice it.
To convert it to a list, use list()
.
all_commenter_ids = PhotoComment.objects.filter(which_photo=which_photo).order_by('-id').values_list('submitted_by', flat=True)[:25]
all_commenter_ids = list(all_commenter_ids)
You might be able to start the queryset from your User
model instead of using values_list
. You haven't shown your models, so the following code is a guess:
from django.db.models import Q
commenters = User.objects.filter(Q(id=which_photo.owner_id)|Q(photocomment=which_photo))
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