Python中通过键树数组动态获取并修改字典值的方法

核心思路 #

要实现这个需求，关键是遍历key_tree逐步定位到目标值的父容器（可能是列表或字典），以及目标值对应的最后一个键/索引——因为直接修改值本身无法影响原结构，必须操作它所在的父容器。

实现代码 #

person_dict = [{"person": {"first_name": "John", "age_of_children": [1, 8, 13]}}]

def access_and_update(data, key_tree, new_value=None):
    # 遍历键树的前n-1个元素，定位到目标值的父容器
    current_container = data
    for key in key_tree[:-1]:
        current_container = current_container[key]
    
    # 获取目标值的直接键/索引
    target_key = key_tree[-1]
    
    # 如果传入新值则修改，同时返回修改前的旧值
    if new_value is not None:
        old_value = current_container[target_key]
        current_container[target_key] = new_value
        return old_value
    # 未传入新值则仅返回当前值
    return current_container[target_key]

# 示例1：修改first_name
key_tree1 = [0, "person", "first_name"]
old_name = access_and_update(person_dict, key_tree1, "Jane")
print(old_name)  # 输出: John
print(person_dict)  # 输出: [{"person": {"first_name": "Jane", "age_of_children": [1, 8, 13]}}]

# 示例2：修改age_of_children数组
key_tree2 = [0, "person", "age_of_children"]
old_ages = access_and_update(person_dict, key_tree2, [2, 9, 14])
print(old_ages)  # 输出: [1, 8, 13]
print(person_dict)  # 输出: [{"person": {"first_name": "Jane", "age_of_children": [2, 9, 14]}}]

# 示例3：仅获取值不修改
key_tree3 = [0, "person", "first_name"]
current_name = access_and_update(person_dict, key_tree3)
print(current_name)  # 输出: Jane

细节说明 #

• 兼容列表与字典：不管父容器是列表（用数字索引）还是字典（用字符串键），current_container[key]的语法都能正常工作，无需额外判断。
• 灵活操作：通过new_value参数控制是仅读取值还是同时修改，满足两种场景需求。

内容的提问来源于stack exchange，提问作者ahmadux