在用Python进行YAML的双程倾倒过程中，是否有一种方法来维护秩序？

Question

我试图从YAML文件中加载一些数据并将其放回原处：

services:
  dc01:
    sw-06-50001:
      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-09-50002:
      servers:
      - {ip: 10.255.206.18, port: 50002, weight: 100}
      - {ip: 10.255.206.19, port: 50002, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50002}
    sw-06-50003:
      servers:
      - {ip: 10.255.206.12, port: 50003, weight: 100}
      - {ip: 10.255.206.13, port: 50003, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50003}
    sw-09-50004:
      servers:
      - {ip: 10.255.206.18, port: 50004, weight: 100}
      - {ip: 10.255.206.19, port: 50004, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50004}

在这方面：

import ruamel.yaml as yaml
with open('filename.yml', 'r') as stream:
    outdata = yaml.load(stream,Loader=yaml.Loader)

yaml.dump(outdata,'filename_out.yml')

我需要保留列表中的所有格式和数据顺序，但是输出转储结果是按字母顺序由sw-xx排序。钥匙：

services:
  dc01:
    sw-06-50001:
      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-06-50003:
      servers:
      - {ip: 10.255.206.12, port: 50003, weight: 100}
      - {ip: 10.255.206.13, port: 50003, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50003}
    sw-09-50002:
      servers:
      - {ip: 10.255.206.18, port: 50002, weight: 100}
      - {ip: 10.255.206.19, port: 50002, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50002}
    sw-09-50004:
      servers:
      - {ip: 10.255.206.18, port: 50004, weight: 100}
      - {ip: 10.255.206.19, port: 50004, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50004}

我如何才能在倾销时保留原始的条目顺序？

Answer 1

您正在进行往返，但您没有使用ruamel.yaml的往返功能。相反，您使用的是过时的PyYAML兼容性、load和dump函数。

相反，您应该实例化一个ruamel.yaml.YAML()实例，并使用该实例的load和dump方法，它们默认为双程，保留顺序(以及注释、标记名称等)。

import sys
import ruamel.yaml

yaml_str = """\
services:
  dc01:
    sw-06-50001:  # first
      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-09-50002:
      servers:
      - {ip: 10.255.206.18, port: 50002, weight: 100}
      - {ip: 10.255.206.19, port: 50002, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50002}
    sw-06-50003:  # third
      servers:
      - {ip: 10.255.206.12, port: 50003, weight: 100}
      - {ip: 10.255.206.13, port: 50003, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50003}
    sw-09-50004:
      servers:
      - {ip: 10.255.206.18, port: 50004, weight: 100}
      - {ip: 10.255.206.19, port: 50004, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50004}
"""

yaml = ruamel.yaml.YAML()
# yaml.indent(mapping=4, sequence=4, offset=2)
# yaml.preserve_quotes = True
data = yaml.load(yaml_str)
yaml.dump(data, sys.stdout)

这意味着：

services:
  dc01:
    sw-06-50001:  # first
      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-09-50002:
      servers:
      - {ip: 10.255.206.18, port: 50002, weight: 100}
      - {ip: 10.255.206.19, port: 50002, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50002}
    sw-06-50003:  # third
      servers:
      - {ip: 10.255.206.12, port: 50003, weight: 100}
      - {ip: 10.255.206.13, port: 50003, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50003}
    sw-09-50004:
      servers:
      - {ip: 10.255.206.18, port: 50004, weight: 100}
      - {ip: 10.255.206.19, port: 50004, weight: 90}
      virtual: {ip: 192.168.1.4, port: 50004}

或者万一你的YAML在一个文件中：

from pathlib import Path
from ruamel.yaml import YAML

# the recommended extension for YAML files has been .yaml since 2006.
file_name = Path('filename.yaml')  
file_out = Path('filename_out.yaml')

yaml = YAML()
outdata = yaml.load(file_name)
yaml.dump(outdata, file_out)