python-3.x - 如何在 ruamel yaml 中定义新字典的样式？

Question

作为问题Is there a way to preserve order while round-trip dumping YAML in Python?得到解决，数据结构被正确导入，样式属性设置正确，等等。我写了一些代码来插入嵌套的 CommentedMap() 字典 (sw-99-54321)，其中包含一些字典和列表，例如:

  dc01:
    sw-06-50001:  # existing entry
      servers:
      - {ip: 10.255.206.12, port: 50001, weight: 100}
      - {ip: 10.255.206.13, port: 50001, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50001}

    sw-99-54321:  # the entry I am trying to add   
      servers:
      - ip: 192.168.1.1
        port: '65535'
        weight: 100
      - ip: 192.168.1.2
        port: '65534'
        weight: 90
      virtual:
        ip: 192.168.1.1
        port: 65532

我想以与现有“sw-06-50001”相同的方式格式化“sw-99-54321”。

我知道样式绑定(bind)到 <var>.fa.__flow_style属性，但我不能直接更改它:

data['services']['dc01']['sw-99-54321']['servers'].fa.set_flow_style='True'
Traceback (most recent call last):
  File "<input>", line 1, in <module>
AttributeError: 'Format' object attribute 'set_flow_style' is read-only 

有没有办法设置它，或者以其他方式为某些元素定义 block 样式？

Answer 1

由于您的示例具有流样式，您可以做两件事

1) 显式设置流样式:

import sys
import ruamel.yaml

yaml_str = """\
dc01:
  sw-06-50001:  #existed entry
    servers:
    - {ip: 10.255.206.12, port: 50001, weight: 100}
    - {ip: 10.255.206.13, port: 50001, weight: 90}
    virtual: {ip: 192.168.1.4, port: 50001}
"""

yaml = ruamel.yaml.YAML()
# yaml.indent(mapping=4, sequence=4, offset=2)
# yaml.preserve_quotes = True
data = yaml.load(yaml_str)
data['dc01']['sw-99-54321'] = n = {}
n['servers'] = l = []
l.append(ruamel.yaml.comments.CommentedMap([('ip', '192.168.1.1'), ('port', '65535'), ('weight', 100)]))
l[-1].fa.set_flow_style()
l.append(ruamel.yaml.comments.CommentedMap([('ip', '192.168.1.2'), ('port', '65534'), ('weight', 90)]))
l[-1].fa.set_flow_style()
n['virtual'] = x = ruamel.yaml.comments.CommentedMap([('ip', '192.168.1.1'), ('port', '65532')])
x.fa.set_flow_style()

yaml.dump(data, sys.stdout)

给出:

dc01:
  sw-06-50001:  #existed entry
    servers:
    - {ip: 10.255.206.12, port: 50001, weight: 100}
    - {ip: 10.255.206.13, port: 50001, weight: 90}
    virtual: {ip: 192.168.1.4, port: 50001}
  sw-99-54321:
    servers:
    - {ip: 192.168.1.1, port: '65535', weight: 100}
    - {ip: 192.168.1.2, port: '65534', weight: 90}
    virtual: {ip: 192.168.1.1, port: '65532'}

2)全局设置所有叶子节点为流式:

import sys
import ruamel.yaml

yaml_str = """\
dc01:
  sw-06-50001:  #existed entry
    servers:
    - {ip: 10.255.206.12, port: 50001, weight: 100}
    - {ip: 10.255.206.13, port: 50001, weight: 90}
    virtual: {ip: 192.168.1.4, port: 50001}
"""

yaml = ruamel.yaml.YAML()
yaml.default_flow_style = None

data = yaml.load(yaml_str)
data['dc01']['sw-99-54321'] = n = ruamel.yaml.comments.CommentedMap()
n['servers'] = l = []
l.append(ruamel.yaml.comments.CommentedMap([('ip', '192.168.1.1'), ('port', '65535'), ('weight', 100)]))
l.append(dict(ip='192.168.1.2', port='65534', weight=90))
n['virtual'] = ruamel.yaml.comments.CommentedMap([('ip', '192.168.1.1'), ('port', '65532')])

yaml.dump(data, sys.stdout)

给出:

dc01:
  sw-06-50001:  #existed entry
    servers:
    - {ip: 10.255.206.12, port: 50001, weight: 100}
    - {ip: 10.255.206.13, port: 50001, weight: 90}
    virtual: {ip: 192.168.1.4, port: 50001}
  sw-99-54321:
    servers:
    - {ip: 192.168.1.1, port: '65535', weight: 100}
    - {ip: 192.168.1.2, port: '65534', weight: 90}
    virtual: {ip: 192.168.1.1, port: '65532'}

使用此方法无需创建 CommentedMap() 实例，您可以使用普通的字典