python使用httpx_sse调用sse流式接口对响应格式为application/json的错误信息的处理

问题描述

调用sse流式接口使用httpx_sse的方式

				import httpx
				from httpx_sse import connect_sse
				# 省略无关代码
				try:
                    with httpx.Client() as client:
                        with connect_sse(client, "GET", url, params=param) as event_source:
                            clear_textbox(response_textbox)
                            # 把 iter_sse() 迭代完, 就相当于处理完了一次流式调用
                            for sse in event_source.iter_sse():
                                # 流式响应中,每次响应体的处理逻辑
                                print(f"generated_answer的值是: '{sse.data}'")
                                response = sse.data
                                if response != '':
                                    # self.response = response
                                    append_text(response_textbox, response)

                except httpx.RequestError as e:
                    print(f"请求错误：{e}")
                except Exception as e:
                    print(f"发生了一个错误：{e}")

httpx_sse的connet_sse源码：

@contextmanager
def connect_sse(
    client: httpx.Client, method: str, url: str, **kwargs: Any
) -> Iterator[EventSource]:
    headers = kwargs.pop("headers", {})
    headers["Accept"] = "text/event-stream"
    headers["Cache-Control"] = "no-store"

    with client.stream(method, url, headers=headers, **kwargs) as response:
        yield EventSource(response)

可以看到connect_sse源码中的headers的"Accept"设置了只接受"text/event-stream"流式结果，正常这么调用是没错的。但是当后端的流式接口因为401权限问题等报错返回了"application/json"格式，如
{ “code”:401, “msg”:“登录过期，请重新登录”, “data”:null} 这样的json格式结果时，以上代码就会报错，因为他不是"text/event-stream"流式响应结果头。那么该怎么办呢？

方案

重新写一个自定义的connect_sse。

import httpx
from httpx_sse import EventSource
from typing import Any, Iterator
from contextlib import contextmanager
import json
# 自定义调用sse接口
    @contextmanager
    def custom_connect_sse(
            self, client: httpx.Client, method: str, url: str, **kwargs: Any
    ) -> Iterator[EventSource]:
        headers = kwargs.pop("headers", {})
        # 只有当没有指定Accept时才添加默认值
        headers["Accept"] = "*/*"
        headers["Cache-Control"] = "no-store"

        with client.stream(method, url, headers=headers, **kwargs) as response:
            content_type = response.headers.get('content-type', '').lower()
            json_flag = False
            if 'text/event-stream' in content_type:
                # 处理SSE流
                yield json_flag, EventSource(response)
            elif 'application/json' in content_type:
                # yield response  # 在这里你可以决定如何进一步处理这个JSON响应
                # 读取并合并所有文本块
                text_data = ''.join([chunk for chunk in response.iter_text()])
                # 解析整个响应体为JSON
                json_data = json.loads(text_data)
                json_flag = True
                yield json_flag, json_data

调用代码

# 使用自定义的connect_sse函数
                try:
                    with httpx.Client() as client:
                        with self.custom_connect_sse(client, "GET", url, params=param, headers=headers) as (json_flag, event_source):
                            if json_flag:
                                code = event_source.get("code")
                                msg = event_source.get("msg")
                                print(f"Code: {code}, Message: {msg}")
                            else:
                                full_answer = ""
                                clear_textbox(response_textbox)
                                for sse in event_source.iter_sse():
                                    print(f"generated_answer的值是: '{sse.data}'")
                                    response = sse.data
                                    if response:
                                        append_text(response_textbox, response)
                                        full_answer += response
                                user_record += reply + full_answer + "\n"
                                print(f"user_record:{user_record}")

                except httpx.RequestError as e:
                    print(f"请求错误：{e}")
                except Exception as e:
                    print(f"发生了一个错误：{e}")

关键步骤：
1.设置headers[“Accept”] = “/”，所有响应头都可以接收
2.content_type = response.headers.get(‘content-type’, ‘’).lower() 判断响应头是流式还是json，并用json_flag记录是否json标识，返回不同的结果。如果是json，则循环合并处理chunk块，拼装完整json返回结果（实测第一次就返回完整json结构了，但是代码得这么写）。
3.使用自定义connect_sse方法时，根据json_flag来分别处理成功调用流式结果还是异常的json结果。