Python 以编程方式更新 YAML 文件
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Update YAML file programmatically
提问by Ignacio Verona
I've a Python dict that comes from reading a YAML file with the usual
我有一个 Python dict，它来自于用通常的方式读取 YAML 文件
yaml.load(stream)
I'd like to update the YAML file programmatically given a path to be updated like:
我想以编程方式更新 YAML 文件，给出要更新的路径，例如：
group1,option1,option11,value
组 1、选项 1、选项 11、值
and save the resulting dict again as a yaml file. I'm facing the problem of updating a dicntionary, taking into account that the path is dynamic (let's say a user is able to enter the path through a simple CLI I've created using Cmd).
并将结果字典再次保存为 yaml 文件。我面临更新字典的问题，考虑到路径是动态的（假设用户能够通过我使用 Cmd 创建的简单 CLI 输入路径）。
Any ideas?
有任何想法吗？
thanks!
谢谢！
UPDATELet me be more specific on the question: The issue is with updating part of a dictionary where I do not know in advance the structure. I'm working on a project where all the configuration is stored on YAML files, and I want to add a CLI to avoid having to edit them by hand. This a sample YAML file, loaded to a dictionary (config-dict) using PyYaml:
更新让我更具体地说明这个问题：问题在于更新我事先不知道结构的字典的一部分。我正在处理一个所有配置都存储在 YAML 文件中的项目，我想添加一个 CLI 以避免手动编辑它们。这是一个示例 YAML 文件，使用 PyYaml 加载到字典 (config-dict)：
config:
a-function: enable
b-function: disable
firewall:
NET:
A:
uplink: enable
downlink: enable
B:
uplink: enable
downlink: enable
subscriber-filter:
cancellation-timer: 180
service:
copy:
DS: enable
remark:
header-remark:
DSC: enable
remark-table:
port:
linkup-debounce: 300
p0:
mode: amode
p1:
mode: bmode
p2:
mode: amode
p3:
mode: bmode
I've created the CLI with Cmd, and it's working great even with autocompletion. The user may provide a line like:
我已经使用 Cmd 创建了 CLI，即使使用自动完成功能，它也能很好地工作。用户可以提供如下一行：
config port p1 mode amode
So, I need to edit:
所以，我需要编辑：
config-dict['config']['port']['p1']['mode'] and set it to 'amode'. Then, use yaml.dump() to create the file again. Another possible line would be:
config-dict['config']['port']['p1']['mode'] 并将其设置为 'amode'。然后，使用 yaml.dump() 再次创建文件。另一个可能的行是：
config a-function enable
So config-dict['config']['a-function'] has to be set to 'enable'.
所以 config-dict['config']['a-function'] 必须设置为 'enable'。
My problem is when updating the dictionary. If Python passed values as a reference would be easy: Just iterate through the dict until the right value is found and save it. Actually this is what I'm doing for the Cmd autocomplete. But I don't know how to do the update.
我的问题是更新字典时。如果 Python 将值作为引用传递会很容易：只需遍历 dict 直到找到正确的值并保存它。实际上，这就是我为 Cmd 自动完成所做的。但我不知道如何进行更新。
Hope I explained myself better now!
希望我现在更好地解释自己！
Thanks in advance.
提前致谢。
回答by Jan Vlcinsky
In fact the solution follows simple patter: load - modify - dump:
事实上，解决方案遵循简单的模式：加载 - 修改 - 转储：
Before playing, be sure you have pyyaml installed:
在玩之前，请确保您已安装 pyyaml：
$ pip install pyyaml
testyaml.py
testyaml.py
import yaml
fname = "data.yaml"
dct = {"Jan": {"score": 3, "city": "Karvina"}, "David": {"score": 33, "city": "Brno"}}
with open(fname, "w") as f:
yaml.dump(dct, f)
with open(fname) as f:
newdct = yaml.load(f)
print newdct
newdct["Pipi"] = {"score": 1000000, "city": "Stockholm"}
with open(fname, "w") as f:
yaml.dump(newdct, f)
Resulting data.yaml
结果 data.yaml
$ cat data.yaml
David: {city: Brno, score: 33}
Jan: {city: Karvina, score: 3}
Pipi: {city: Stockholm, score: 1000000}
回答by Dan Temkin
Updating seems to the one place where pyyaml falls short. You cannot even use yaml.load on a file that was opened in (a)ppend mode without an exception. Now this may be a bit tedious for complex dictionaries but if each added item represents a separate case or document you could handle it as if it were any other text file.
更新似乎是 pyyaml 不足的地方。您甚至不能在 (a) ppend 模式下打开的文件上使用 yaml.load ，无一例外。现在这对于复杂的词典来说可能有点乏味，但是如果每个添加的项目代表一个单独的案例或文档，您可以像处理任何其他文本文件一样处理它。
newinfo = {"Pipi": {"score": 100000, "city": "Stockholm"}}
with open(fname, "a") as f:
sep = "\n" # For distinct documents use "\n...\n" as separator
# Pay attention to where you put the separator.
# if the file exists and is in traditional format place at
# beginning of string. else place at the end.
infostring = "{}".format(newinfo)
f.write(infostring + sep)
While this doesn't necessarily help with value updating, it does allow for file updating. You might also look into using json.dump on the file. I know it is in YAML but the formats are largely compatible unless you are using the python-object storage feature in YAML.
虽然这不一定有助于值更新，但它确实允许文件更新。您也可以考虑在文件上使用 json.dump。我知道它在 YAML 中，但格式在很大程度上兼容，除非您在 YAML 中使用 python 对象存储功能。
For a OS agnostic approach to carriage character assignment remember to use os.linesep.
对于与操作系统无关的回车字符分配方法，请记住使用 os.linesep。
Best of luck. Hope this helps.
祝你好运。希望这可以帮助。
回答by Jyoti Arora
Try out this method, i am using for updating yaml or json files.
def update_dictionary_recursively(dictionary, key, value, key_separator="."):
"""Update givendictionarywith the givenkeyandvalue`.
试试这个方法，我用来更新 yaml 或 json 文件。
def update_dictionary_recursively(dictionary, key, value, key_separator="."):
"""Update given字典with the given键值and`。
if dictionary contains value as dict E.g. {key1:value1, key2:{key3, {key4:value4}}} and you have to
update key4 then `key` should be given as `key2.key3.key4`.
If dictionary contains value as list E.g. {key1:{key2:[{key3:valie3}, {key4:value4}]}} and you have to update
key4 then `key` should be given as `key1.key2[1].key4`.
:param dictionary: Dictionary that is to be updated.
:type dictionary: dict
:param key: Key with which the dictionary is to be updated.
:type key: str
:param value: The value which will be used to update the key in dictionary.
:type value: object
:param key_separator: Separator with which key is separated.
:type key_separator str
:return: Return updated dictionary.
:rtype: dict
"""
index = key.find(key_separator)
if index != -1:
current_key = key[0:index]
key = key[index + 1:]
try:
if '[' in current_key:
key_index = current_key.split('[')
current_key = key_index[0]
list_index = int(key_index[1].strip(']'))
dictionary[current_key][list_index] = update_dictionary_recursively(
dictionary[current_key][list_index], key, value, key_separator)
else:
dictionary[current_key] = update_dictionary_recursively(dictionary[current_key],
key, value, key_separator)
except (KeyError, IndexError):
return dictionary
else:
if '[' in key:
key_index = key.split('[')
list_index = int(key_index[1].strip(']'))
if list_index > len(dictionary) - 1:
return dictionary
dictionary[list_index] = value
else:
if key not in dictionary:
return dictionary
dictionary[key] = value
return dictionary
`
`
回答by Fabio Caccamo
It is very simple to do it with python-benedict, a solid python dict subclass that support IO operations with many formats, including yaml.
这是非常简单的做到这一点的python-benedict，坚实的Python字典子类，与众多格式的支持IO操作，包括yaml。
Installation: pip install python-benedict
安装： pip install python-benedict
You can initialize it directly from the yamlfile:
您可以直接从yaml文件初始化它：
from benedict import benedict
f = 'data.yaml'
d = benedict.from_yaml(f)
d['Pipi'] = {'score': 1000000, 'city': 'Stockholm'}
# benedict supports keypath (dot syntax by default),
# so it's possible to update nested values easily:
d['Pipi.score'] = 2000000
print(d['Pipi']) # -> {'score': 2000000, 'city': 'Stockholm'}
d.to_yaml(filepath=f)
Here the library repository and the documentation: https://github.com/fabiocaccamo/python-benedict
这里是库存储库和文档：https: //github.com/fabiocaccamo/python-benedict
回答by ChaosPredictor
If you can do it with JSON, much easier.
如果你可以用 JSON 来做，那就容易多了。
