如何使用 Python (Django) 制作 SSE？
[英]How can I make SSE with Python (Django)?
问题描述
I have two different pages, one (A) that displays data taken from a model object, and one (B) that changes its fields.
我有两个不同的页面，一个 (A) 显示从模型对象中获取的数据，另一个 (B) 更改其字段。 I would like that when the post data is sent from B to the server, the server changes the values in A. What is the best way to do it?我希望当发布数据从 B 发送到服务器时，服务器会更改 A 中的值。最好的方法是什么？
This example could work for me but it's in PHP... there is a way to replicate it whit Python?这个例子对我有用，但它是用 PHP 编写的……有没有办法用 Python 复制它？ https://www.w3schools.com/html/html5_serversentevents.asp https://www.w3schools.com/html/html5_serversentevents.asp
3 个解决方案
解决方案1
19 2019-04-04 18:42:26
This is working example from w3schools in Django:这是 Django 中 w3schools 的工作示例：
template模板
<!DOCTYPE html>
<html>
<body>
<h1>Getting server updates</h1>
<div id="result"></div>
<script>
if(typeof(EventSource) !== "undefined") {
var source = new EventSource("stream/");
source.onmessage = function(event) {
document.getElementById("result").innerHTML += event.data + "<br>";
};
} else {
document.getElementById("result").innerHTML = "Sorry, your browser does not support server-sent events...";
}
</script>
</body>
</html>
views意见
import datetime
import time
from django.http import StreamingHttpResponse
def stream(request):
def event_stream():
while True:
time.sleep(3)
yield 'data: The server time is: %s\n\n' % datetime.datetime.now()
return StreamingHttpResponse(event_stream(), content_type='text/event-stream')
urls网址
urlpatterns = [
path('stream/', views.stream, name='stream')
]
Update:更新：
If you want to manage your notifications you can create the model like:如果您想管理您的通知，您可以创建如下模型：
from django.db import models
class Notification(models.Model):
text = models.CharField(max_length=200)
user = models.ForeignKey(User, on_delete=models.CASCADE)
sent = models.BooleanField(default=False)
Then create the view that is looking for the first unsent notification and sends it:然后创建寻找第一个未发送通知的视图并发送它：
@login_required
def stream(request):
def event_stream():
while True:
time.sleep(3)
notification = Notification.objects.filter(
sent=False, user=request.user
).first()
text = ''
if notification:
text = notification.text
notification.sent = True
notification.save()
yield 'data: %s\n\n' % text
return StreamingHttpResponse(event_stream(), content_type='text/event-stream')
And the send_notification function that creates an entry in the Notification model (just call this function from anywhere in your code):以及在Notification模型中创建条目的send_notification函数（只需从代码中的任何位置调用此函数）：
def send_notification(user, text):
Notification.objects.create(
user=user, text=text
)
That's it, simple as that.就是这样，就这么简单。
解决方案2
6 2019-06-18 00:39:25
After reading this , I think I understood the whole thing (please comment if I'm wrong).看完这篇，我想我明白了整件事（如果我错了，请评论）。
Django does NOT natively support keep-alive connections. Django 本身不支持保持活动连接。 This means, when the client gets the message from the server, the connection is immediately closed after (like any classic HTTP request/response cycle).这意味着，当客户端从服务器获取消息时，连接会立即关闭（就像任何经典的 HTTP 请求/响应周期一样）。
What's different with text/event-stream request, is that the client automatically tries to reconnect to the server every second (the length can be changed with a retry parameter).与text/event-stream请求不同的是，客户端每秒自动尝试重新连接到服务器（可以使用retry参数更改长度）。
Unfortunately, it seems using SSE in that case has no interest since it has the same con's that polling (ie. a request/response cycle occurs each X seconds).不幸的是，在这种情况下使用 SSE 似乎没有兴趣，因为它具有与轮询相同的缺点（即每 X 秒发生一个请求/响应周期）。
As expected and mentioned in other answers, I would need django-channels to create a persistent connection that prevent HTTP request/response overheads and ensure the message is sent immediately.正如预期并在其他答案中提到的那样，我需要 django-channels 来创建一个持久连接，以防止 HTTP 请求/响应开销并确保立即发送消息。
解决方案3
1 2021-03-06 01:40:52
As mentioned in other answers, you will need to use Django Channels to properly handle asynchronous communication without tying up threads.正如其他答案中提到的，您将需要使用 Django Channels 来正确处理异步通信，而不会占用线程。
For an example, see the django-eventstream library which uses Channels to implement SSE.例如，请参阅使用 Channels 实现 SSE的 django-eventstream 库。
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