如何将'key=value'字符串转为嵌套字典并修正Python代码问题

原代码在处理a.b.c=ddd这类嵌套键值对时，错误地将每个层级的键都作为顶层键添加到master_config中，导致生成扁平字典。以下是修正后的代码，重点修改注释Set the master config value for the current setting下方的逻辑：

### For context - in reality I use an argument parser with two args.
###   --config-file - Path to a YAML configuration file. If present,
###     this file will be read into Python as a dictionary called
###     `master_config`. If not, an empty dictionary of the same name
###     will be created.
###   --configs - Single 'key=value' settings that will be read into
###     `master_config` and either override settings defined in the
###     YAML configuration file, or set a value.

master_config = {'foo': 'baz'}
configs = ['foo=bar', 'a.b.c=ddd']

for config in configs:

    # Split the setting into key and value.
    k, v = config.split('=', 1)

    # Split the key, if it's nested.
    ks = k.split('.')

    # Set the master config value for the current setting.
    current_dict = master_config
    # 遍历除最后一个键以外的所有层级
    for key in ks[:-1]:
        # 如果键不存在，或者对应的值不是字典，则创建空字典
        if key not in current_dict or not isinstance(current_dict[key], dict):
            current_dict[key] = {}
        # 进入下一层字典
        current_dict = current_dict[key]
    # 设置最后一个键的值
    current_dict[ks[-1]] = v

print(master_config)

修正逻辑说明 #

1. 用current_dict变量跟踪当前操作的字典层级，初始指向master_config
2. 遍历嵌套键的前N-1个层级：
   • 检查当前层级的键是否存在，且对应的值是字典；如果不满足则创建空字典
   • 将current_dict切换为当前键对应的子字典，逐步深入嵌套结构
3. 最后在最内层的字典中设置最后一个键的值，确保嵌套结构正确生成

运行修正后的代码，输出结果为：

{'foo': 'bar', 'a': {'b': {'c': 'ddd'}}}

完全符合预期的嵌套字典结构。

内容的提问来源于stack exchange，提问作者David Gard