如何拉取没有特定结构的特定json字段

import json

def extract_field(json_data, field_name):
    if isinstance(json_data, dict):
        if field_name in json_data:
            return json_data[field_name]
        else:
            for value in json_data.values():
                result = extract_field(value, field_name)
                if result is not None:
                    return result
    elif isinstance(json_data, list):
        for item in json_data:
            result = extract_field(item, field_name)
            if result is not None:
                return result

    return None

# 示例JSON数据
json_str = '''
{
    "name": "John",
    "age": 30,
    "address": {
        "street": "123 Main St",
        "city": "New York"
    },
    "contacts": [
        {
            "type": "email",
            "value": "john@example.com"
        },
        {
            "type": "phone",
            "value": "555-1234"
        }
    ]
}
'''

# 解析JSON数据
data = json.loads(json_str)

# 提取特定字段
field = "value"
result = extract_field(data, field)
print(result)