使用Python http.client发起请求时触发AttributeError错误求助

问题代码 #

headers = {
'Content-Type': 'application/json;charset=UTF-8',
'Cookie': 'A'}

body = {
"grant_type": "client_credentials",
"client_id": "test client",
"client_secret": "client secret",
"scope": "read"}

conn.request("POST", url, headers, json.dumps(body))

错误信息 #

[ERROR] 2024-08-20T17:30:28.313Z cadf1225-4977-4fa2-8435-1b6f650d0e55 
Canary error: Traceback (most recent call last): File "/var/task/index.py", 
line 92, in handle_canary response = handler(event, context) File "/opt/python/apiCanaryBlueprint.py", line 77, in handler main() File "/opt/python/apiCanaryBlueprint.py", line 70, in main verify_request(method1, url1, payload1, headers1) File "/opt/python/apiCanaryBlueprint.py", line 27, in verify_request conn.request(method, url, headers=json.dumps(body)) File "/var/lang/lib/python3.9/http/client.py", line 1285, in request self._send_request(method, url, body, headers, encode_chunked) File "/var/lang/lib/python3.9/http/client.py", line 1325, in _send_request for hdr, value in headers.items(): AttributeError: 'str' object has no attribute 'items'

错误原因 #

错误核心是conn.request()的参数顺序错误。http.client.HTTPConnection.request()的标准参数顺序为：
request(method, url, body=None, headers={}, encode_chunked=False)

代码中把headers放到了第三个参数（body参数位），把序列化后的body字符串json.dumps(body)放到了第四个参数（headers参数位）。框架处理时会把这个字符串当作headers字典调用items()方法，而字符串没有该属性，因此抛出AttributeError。

解决方法 #

方法1：调整参数顺序 #

调换body和headers的位置，匹配标准参数顺序：

headers = {
'Content-Type': 'application/json;charset=UTF-8',
'Cookie': 'A'}

body = {
"grant_type": "client_credentials",
"client_id": "test client",
"client_secret": "client secret",
"scope": "read"}

conn.request("POST", url, json.dumps(body), headers)

方法2：使用关键字参数（推荐） #

通过明确指定参数名，彻底避免参数顺序混淆：

conn.request("POST", url, body=json.dumps(body), headers=headers)

内容的提问来源于stack exchange，提问作者girish