Python中在JSON列表查找指定键项触发KeyError，求解决

错误原因 #

1. 直接访问不存在的字典键触发KeyError：
   循环payload["details"]时，第一个元素是{"ABC1234": {...}}，这个字典里没有DEF5678键，用i['DEF5678']直接访问不存在的键会抛出KeyError。
2. 多余的json.loads调用：
   你定义的payload已经是Python字典，不是JSON字符串，json.loads()只能处理字符串/字节类型，这行代码会额外触发TypeError。

修复后的代码 #

方法1：用dict.get()安全访问（不存在的键返回None）

payload  = {"name": "John",
           "age": 30,
           "city": "New York",
           "details": [
                        {"ABC1234": 
                          {"name": "Office mover",
                          "ratings": "poor"}
                          },

                        {"DEF5678": 
                          {"name": "Installer",
                          "ratings": "good"}
                        }
                      ],
                      "id": "XYZ12344",
                      "type": "hire"
             }

# 去掉多余的json.loads，直接使用字典
for i in payload["details"]:
    if i.get('DEF5678') is not None:
        print(i)
        # 如果需要获取内部的name和ratings，可以继续访问：
        # print(i['DEF5678']['name'], i['DEF5678']['ratings'])

方法2：先检查键是否存在于字典中

payload  = {"name": "John",
           "age": 30,
           "city": "New York",
           "details": [
                        {"ABC1234": 
                          {"name": "Office mover",
                          "ratings": "poor"}
                          },

                        {"DEF5678": 
                          {"name": "Installer",
                          "ratings": "good"}
                        }
                      ],
                      "id": "XYZ12344",
                      "type": "hire"
             }

for i in payload["details"]:
    if 'DEF5678' in i:
        print(i)
        # 访问内部字段示例：
        # info = i['DEF5678']
        # print(f"Name: {info['name']}, Ratings: {info['ratings']}")

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