如何将一个包含JSON值的CSV列转换为4个不同的列？

import csv
import json

# 读取CSV文件
with open('input.csv', 'r') as csvfile:
    reader = csv.DictReader(csvfile)
    
    # 创建新的CSV文件
    with open('output.csv', 'w', newline='') as outfile:
        fieldnames = ['field1', 'field2', 'field3', 'field4']
        writer = csv.DictWriter(outfile, fieldnames=fieldnames)
        writer.writeheader()
        
        # 遍历每一行
        for row in reader:
            # 解析JSON值
            json_value = json.loads(row['json_column'])
            
            # 提取字段值
            field1 = json_value['field1']
            field2 = json_value['field2']
            field3 = json_value['field3']
            field4 = json_value['field4']
            
            # 写入新的CSV文件
            writer.writerow({'field1': field1, 'field2': field2, 'field3': field3, 'field4': field4})