我们使用 YAML 配置来进行服务扩展。通常是这样的:
service:
scalingPolicy:
capacity:
min: 1
max: 1
因此很容易使用基本的 PyYAML 打开并解析为字典以获得
config['service']['scalingPolicy']['capacity']['min']
结果为 1
。问题是一些配置是用点分隔符构建的,例如:
service.scalingPolicy.capacity:
min: 1
max: 1
此配置的基本使用者是 Java 的 Spring,并且以某种方式将其与上面的示例同等对待。但由于还需要使用 Python 解析这些配置 - 我将整个点分隔线作为
config['service.scalingPolicy.capacity']
键。
问题是 - 我如何让 python 解析任何类型的按键组合(
separated by dots
并用 tabulation and :
分隔)。我没有找到 Python YAML 库的相关参数(我已经检查了标准 PyYAML 和 ruamel.yaml
),并且手动处理任何可能的组合似乎是一个疯狂的想法。我唯一可能的想法是编写自己的解析器,但也许我缺少一些东西,所以我不必重新发明自行车。
这并不是微不足道的,使用键来分割查找要容易得多 点递归到嵌套数据结构中。这里你有一个嵌套的 数据结构和不同的
[key]
查找意味着不同的事情
不同级别。
如果你在默认往返模式下使用
ruamel.yaml
,你可以添加一个类变量
到表示映射的类型,该映射定义了键的拆分内容和实例变量
跟踪已经匹配的前缀:
import sys
import ruamel.yaml
from ruamel.yaml.compat import ordereddict
from ruamel.yaml.comments import merge_attrib
yaml_str = """\
service.scalingPolicy.capacity:
min: 1
max: 1
"""
def mapgetitem(self, key):
sep = getattr(ruamel.yaml.comments.CommentedMap, 'sep')
if sep is not None:
if not hasattr(self, 'splitprefix'):
self.splitprefix = ''
if self.splitprefix:
self.splitprefix += sep + key
else:
self.splitprefix = key
if self.splitprefix not in self:
for k in self.keys():
if k.startswith(self.splitprefix):
break
else:
raise KeyError(self.splitprefix)
return self
key = self.splitprefix
delattr(self, 'splitprefix') # to make the next lookup work from start
try:
return ordereddict.__getitem__(self, key)
except KeyError:
for merged in getattr(self, merge_attrib, []):
if key in merged[1]:
return merged[1][key]
raise
old_mapgetitem = ruamel.yaml.comments.CommentedMap.__getitem__ # save the original __getitem__
ruamel.yaml.comments.CommentedMap.__getitem__ = mapgetitem
ruamel.yaml.comments.CommentedMap.sep = '.'
yaml = ruamel.yaml.YAML()
# yaml.indent(mapping=4, sequence=4, offset=2)
# yaml.preserve_quotes = True
config = yaml.load(yaml_str)
print('min:', config['service']['scalingPolicy']['capacity']['min'])
print('max:', config['service']['scalingPolicy']['capacity']['max'])
print('---------')
config['service']['scalingPolicy']['capacity']['max'] = 42
# and dump with the original routine, as it uses __getitem__
ruamel.yaml.comments.CommentedMap.__getitem__ = old_mapgetitem
yaml.dump(config, sys.stdout)
给出:
min: 1
max: 1
---------
service.scalingPolicy.capacity:
min: 1
max: 42
我找到了另一种解决方案,使用 pyyaml 用点替换递归字典键。我希望能有所帮助。
import yaml
my_yaml = """
service.scalingPolicy.capacity:
min: 1
max: 50
"""
def convert_to_dict(source_string, split_symbol='.', value=None):
return_value = value
elements = source_string.split(split_symbol)
for element in reversed(elements):
if element:
return_value = {element: return_value}
return return_value
def split_dots(source_dict):
return_value = {}
for key in source_dict:
new_value = source_dict[key]
if isinstance(source_dict[key], dict):
new_value = split_dots(source_dict[key])
new_key = key
if '.' in key:
new_dict = convert_to_dict(key, '.', new_value)
new_key = list(new_dict.keys())[0]
new_value = new_dict[new_key]
if new_key in return_value:
return_value[new_key].update(new_value)
else:
return_value[new_key] = new_value
return return_value
def main():
try:
yaml_dict = yaml.safe_load(my_yaml)
processed_yaml_dict = split_dots(yaml_dict)
print("Min:", processed_yaml_dict['service']['scalingPolicy']['capacity']['min'])
print("Max:", processed_yaml_dict['service']['scalingPolicy']['capacity']['max'])
data = yaml.dump(processed_yaml_dict, indent=True)
print("New yaml:", data)
except yaml.YAMLError as exc:
print(exc)
if __name__ == "__main__":
main()