我有一个用户模型，每个用户可以通过此关联获得许多帖子：
class Post(models.Model):
...
user = models.ForeignKey('User', related_name='posts')
，每个帖子都有一个like_count（整数字段），我希望得到的用户（沿着他们的帖子）有更多的帖子，这些帖子多被m次，我这样做：
User.objects.prefetch_related(Prefetch('posts', queryset=Post.objects.filter(like_count__gte=m), to_attr='top_posts')).annotate(top_post_count=Count('top_posts')).filter(top_post_count__gte=n)
但是，我明白了：
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/local/lib/python3.4/dist-packages/django/db/models/query.py", line 912, in annotate
clone.query.add_annotation(annotation, alias, is_summary=False)
File "/usr/local/lib/python3.4/dist-packages/django/db/models/sql/query.py", line 971, in add_annotation
summarize=is_summary)
File "/usr/local/lib/python3.4/dist-packages/django/db/models/aggregates.py", line 19, in resolve_expression
c = super(Aggregate, self).resolve_expression(query, allow_joins, reuse, summarize)
File "/usr/local/lib/python3.4/dist-packages/django/db/models/expressions.py", line 513, in resolve_expression
c.source_expressions[pos] = arg.resolve_expression(query, allow_joins, reuse, summarize, for_save)
File "/usr/local/lib/python3.4/dist-packages/django/db/models/expressions.py", line 463, in resolve_expression
return query.resolve_ref(self.name, allow_joins, reuse, summarize)
File "/usr/local/lib/python3.4/dist-packages/django/db/models/sql/query.py", line 1462, in resolve_ref
self.get_initial_alias(), reuse)
File "/usr/local/lib/python3.4/dist-packages/django/db/models/sql/query.py", line 1402, in setup_joins
names, opts, allow_many, fail_on_missing=True)
File "/usr/local/lib/python3.4/dist-packages/django/db/models/sql/query.py", line 1327, in names_to_path
"Choices are: %s" % (name, ", ".join(available)))
django.core.exceptions.FieldError: Cannot resolve keyword 'top_posts' into field. Choices are: ...
答案 0 :(得分：1)
docs解释它被分配给QuerySet项目中根据function hasUserMedia(){
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
return !!navigator.getUserMedia;
}
function hasRTCPeerConnection() {
window.RTCPeerConnection = window.RTCPeerConnection || window.webkitRTCPeerConnection || window.mozRTCPeerConnection;
return !!window.RTCPeerConnection;
}
//This function will create our RTCPeerConnection objects, set up the SDP offer and response, and find the ICE candidates for both peers. page 48
function startPeerConnection(stream) {
var configuration = {
// Uncomment this code to add custom iceServers
"iceServers": [{ "url": "stun:stun.1.google.com:19302" }]
};
yourConnection = new webkitRTCPeerConnection(configuration);
theirConnection = new webkitRTCPeerConnection(configuration);
// Setup stream listening
yourConnection.addStream(stream);
theirConnection.onaddstream = function (e) {
theirVideo.src = window.URL.createObjectURL(e.stream);
};
// Setup ice handling
yourConnection.onicecandidate = function (event) {
if (event.candidate){
theirConnection.addIceCandidate(new RTCIceCandidate(event.candidate));
}
};
theirConnection.onicecandidate = function (event) {
if (event.candidate) {
yourConnection.addIceCandidate(new RTCIceCandidate(event.candidate));
}
};
// Begin the offer
yourConnection.createOffer(function (offer) {
yourConnection.setLocalDescription(offer);
theirConnection.setRemoteDescription(offer);
theirConnection.createAnswer(function (offer) {
theirConnection.setLocalDescription(offer);
yourConnection.setRemoteDescription(offer);
});
});
}
var yourVideo = document.querySelector("#yours"),
theirVideo = document.querySelector("#theirs"),
yourConnection, theirConnection;
if (hasUserMedia()) {
navigator.getUserMedia({ video: true, audio: false }, function (stream) {
yourVideo.src = window.URL.createObjectURL(stream);
if (hasRTCPeerConnection()) {
startPeerConnection(stream);
} else {
alert("Sorry, your browser does not support WebRTC.");
}
}, function (error) {
console.log(error);
}
);
} else {
alert("Sorry, your browser does not support WebRTC.");
}
参数命名的属性。
我认为这并不意味着它可以作为模型字段访问，后续注释可以链接到该模型字段。
您可能需要将其分为两个步骤。
修改：该问题已评论说过滤器可以链接但注释不能。