Python多行GraphQL字符串格式化出现KeyError问题求助

问题场景 #

调用Python函数发起GraphQL请求时，遇到KeyError报错，指向查询字符串中的willObfuscateQuestions (questionIdList部分，核心问题出在多行GraphQL字符串的格式化处理上。

代码示例 #

def verify_obs():
    question_list = ["baae592c-ec9e-11e3-99de-021505f49f8a","37b5556a-b229-4010-8920-6fc72e5f629e","df3c569b-3bb7-4376-8c33-7f20603a2790","a6bfd272-aad0-4e5d-9a5e-c4a1268ea4ba","e1e9ca6a-4ceb-476e-a87c-7d591486c8da"]

    my_query = '''query {
  willObfuscateQuestions (questionIdList: {0}) {
    questionId
    state
    examId
    endTime
    startTime
  }
}'''.format(question_list)

    ds_response = requests.post(
        url='<end point here>',
        headers={'Content-Type': 'application/json'},
        json={'query': my_query}
    )
    response_list = ds_response.json()['data']['willObfuscateQuestions']
    print(response_list)
    for item in response_list:
        state = item['state']
        if state == 'Obfuscated' and int(ds_response.status_code) == 200:
            print('Question is obfuscated')
            return 0
        else:
            raise Exception('Obfuscation failed with response - ', ds_response.json())

报错信息 #

Traceback (most recent call last):
  File "/Users/ubhatia/Documents/RFSetup/karma-moderation-pipeline/robot-tests/KarmaModeration/Config/methods.py", line 198, in <module>
    print(verify_obs())
  File "/Users/ubhatia/Documents/RFSetup/karma-moderation-pipeline/robot-tests/KarmaModeration/Config/methods.py", line 49, in verify_obs
    }'''.format(question_list)
KeyError: '\n  willObfuscateQuestions (questionIdList'

原因分析 #

Python的str.format()方法会把字符串中的{}识别为格式占位符，而你的GraphQL查询里有大量未转义的{和}，这些符号被format误判为需要解析的占位符，导致程序找不到对应键，抛出KeyError。

解决方法 #

1. 转义GraphQL中的大括号 #

把查询字符串里所有非占位符的{改成{{，}改成}}，让format将它们视为普通字符处理：

my_query = '''query {{
  willObfuscateQuestions (questionIdList: {0}) {{
    questionId
    state
    examId
    endTime
    startTime
  }}
}}'''.format(question_list)

2. 稳妥序列化列表参数 #

直接传入Python列表给format虽然暂时能满足格式要求，但如果列表包含特殊字符可能出问题，建议用json.dumps()序列化列表，确保GraphQL能正确解析：

import json

# ...

my_query = '''query {{
  willObfuscateQuestions (questionIdList: {0}) {{
    questionId
    state
    examId
    endTime
    startTime
  }}
}}'''.format(json.dumps(question_list))

3. 完善错误处理逻辑 #

原代码先取响应数据再判断状态码，容易在请求失败时崩溃，建议先检查状态码和GraphQL错误信息：

ds_response = requests.post(...)
if ds_response.status_code != 200:
    raise Exception(f'请求失败，状态码：{ds_response.status_code}，响应：{ds_response.json()}')
response_data = ds_response.json()
if 'errors' in response_data:
    raise Exception(f'GraphQL执行错误：{response_data["errors"]}')
response_list = response_data['data']['willObfuscateQuestions']

内容的提问来源于stack exchange，提问作者UMANG BHATIA