python - 可迭代对象和 Django StreamingHttpResponse

Question

我想用 django 连接到内部 http 服务，我需要缓冲这些服务的 http 响应的输出，因为有些内容非常大。

我正在使用 python 3.6、django 2.0、http.client 和以下代码:

class HTTPStreamIterAndClose():
    def __init__(self, conn, res, buffsize):
        self.conn = conn
        self.res = res
        self.buffsize = buffsize
        self.length = 1

        bytes_length = int(res.getheader('Content-Length'))

        if buffsize < bytes_length:
            self.length = math.ceil(bytes_length/buffsize)

    def __iter__(self):
        return self

    def __next__(self):
        buff = self.res.read(self.buffsize)

        if buff is b'':
            self.res.close()
            self.conn.close()

            raise StopIteration
        else:

            return buff

    def __len__(self):
        return self.length


def passthru_http_service(request, server, timeout, path):
    serv = HTTPService(server, timeout)
    res = serv.request(path)

    response = StreamingHttpResponse(
        HTTPStreamIterAndClose(serv.connection, res, 200),
        content_type='application/json'
    )
    response['Content-Length'] = res.getheader('Content-Length')

    return response

响应为空，我用以下方法测试迭代器:

b''.join(HTTPStreamIterAndClose(serv.connection, res, 200)

一切正常，我不知道为什么不工作。

Answer 1

https://andrewbrookins.com/django/how-does-djangos-streaminghttpresponse-work-exactly/

First, some conditions must be true:

• The client must be speaking HTTP/1.1 or newer
• The request method wasn’t a HEAD
• The response does not include a Content-Length header
• The response status wasn’t 204 or 304

If these conditions are true, then Gunicorn will add a Transfer-Encoding: chunked header to theresponse, signaling to the client that the response will stream inchunks.

In fact, Gunicorn will respond with Transfer-Encoding: chunked even ifyou used an HttpResponse, if those conditions are true!

To really stream a response, that is, to send it to the client inpieces, the conditions must be true, and your response needs to be aniterable with multiple items.

基本上，您需要决定:流式传输还是 Content-Length。

如果您想要断点续传，请使用 Range .