在打开文件进行写入之前以递归方式创建目录 [英] Recursively create directories prior to opening file for writing

问题描述

我需要写一个文件(截断)，并且它本身的路径可能不存在).例如，我想写入/tmp/a/b/c/config ，但是/tmp/a 本身可能不存在.然后， open('/tmp/a/b/c/config'，'w')显然不起作用，因为它没有建立必要的目录.但是，我可以使用以下代码:

I need to write to a file (truncating) and the path it is on itself might not exist). For example, I want to write to /tmp/a/b/c/config, but /tmp/a itself might not exist. Then, open('/tmp/a/b/c/config', 'w') would not work, obviously, since it doesn't make the necessary directories. However, I can work with the following code:

import os

config_value = 'Foo=Bar'  # Temporary placeholder

config_dir = '/tmp/a/b/c'  # Temporary placeholder
config_file_path = os.path.join(config_dir, 'config')

if not os.path.exists(config_dir):
    os.makedirs(config_dir)

with open(config_file_path, 'w') as f:
    f.write(config_value)

还有更多的Python方式可以做到这一点吗?知道Python 2.x和Python 3.x都很好(尽管由于依赖性，我在代码中使用了2.x).

Is there a more Pythonic way to do this? Both Python 2.x and Python 3.x would be nice to know (even though I use 2.x in my code, due to dependency reasons).

推荐答案

如果要在多个位置重复此模式，则可以创建自己的上下文管理器，以扩展 open()并重载<代码> __ enter __():

If you're repeating this pattern in multiple places, you could create your own Context Manager that extends open() and overloads __enter__():

import os

class OpenCreateDirs(open):
    def __enter__(self, filename, *args, **kwargs):
        file_dir = os.path.dirname(filename)
        if not os.path.exists(file_dir):
            os.makedirs(file_dir)

        super(OpenCreateDirs, self).__enter__(filename, *args, **kwargs)

然后您的代码将变为:

import os

config_value = 'Foo=Bar'  # Temporary placeholder
config_file_path = os.path.join('/tmp/a/b/c', 'config')

with OpenCreateDirs(config_file_path, 'w') as f:
    f.write(config_value)

使用open(...)作为f:运行时，要调用的第一个方法是 open .__ enter __().因此，通过在调用 super(...).__ enter __()之前创建目录，可以在尝试打开文件之前创建目录.

The first method to be called when you run with open(...) as f: is open.__enter__(). So by creating directories before calling super(...).__enter__(), you create the directories before attempting to open the file.

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