Contents
14.19. python读写yaml¶
14.19.1. 1.安装PyYAML¶
使用以下命令安装 PyYAML，最好在虚拟环境中
虚拟环境安装参考： https://python.land/virtual-environments/virtualenv
$ pip install pyyaml
On some systems you need to use pip3:
$ pip3 install pyyaml
To use PyYAML in your scripts, import the module as follows. Note that you don’t import ‘pyyaml’, but simply ‘yaml’:
import yaml
14.19.2. 2.使用Python读取和解析YAML文件¶
config.yaml
rest:
url: "https://example.org/primenumbers/v1"
port: 8443
prime_numbers: [2, 3, 5, 7, 11, 13, 17, 19]
parsing_yaml.py
import yaml
with open("config.yaml","r") as file:
prime_service = yaml.safe_load(file)
print(prime_service)
# {'rest': {'url': 'https://example.org/primenumbers/v1', 'port': 8443}, 'prime_numbers': [2, 3, 5, 7, 11, 13, 17, 19]}
print(prime_service['prime_numbers'][0]) # 2
print(prime_service["rest"]["url"])
# https://example.org/primenumbers/v1
14.19.3. 3.使用Python解析YAML字符串¶
您可以使用 yaml.safe_load()来解析各种有效的YAML字符串。这是一个将简单的项目列表解析为 Python列表的示例：
import yaml
names_yaml = """
- 'eric'
- 'justin'
- 'mary-kate'
"""
names = yaml.safe_load(names_yaml)
print(names)
# ['eric', 'justin', 'mary-kate']
14.19.4. 4.解析包含多个YAML文档的文件¶
YAML允许您在一个文件中定义多个文档，并用三个破折号 (—) 分隔它们。
PyYAML 也会愉快地解析这些文件，并返回一个文档列表。您可以使用 yaml.safe_load_all()函数来执行此操作。
此函数返回一个生成器，该生成器又将一个接一个地返回所有文档。
multi_doc.yml
document: 1
name: 'erik'
---
document: 2
name: 'config'
read_multiple_yaml.py
import yaml
with open('multi_doc.yml', 'r') as file:
docs = yaml.safe_load_all(file)
for doc in docs:
print(doc)
14.19.5. 5.将YAML写入转储到文件¶
import yaml
names_yaml = """
- 'eric'
- 'justin'
- 'mary-kate'
"""
names = yaml.safe_load(names_yaml)
with open('names.yaml', 'w') as file:
yaml.dump(names, file)
14.19.6. 6.使用Python将YAML转换为JSON¶
在这个例子中，我们打开一个基于 YAML 的配置文件，用 PyYAML 解析它，然后用 JSON 模块将它写入一个 JSON 文件
config.yml
rest:
url: "https://example.org/primenumbers/v1"
port: 8443
prime_numbers: [2, 3, 5, 7, 11, 13, 17, 19]
yaml-to-json.py
import yaml
import json
with open('config.yml', 'r') as file:
configuration = yaml.safe_load(file)
with open('config.json', 'w') as json_file:
json.dump(configuration, json_file)
output = json.dumps(json.load(open('config.json')), indent=2)
print(output)
这是与非交互式示例相同的代码
import yaml
import json
with open('config.yml', 'r') as file:
configuration = yaml.safe_load(file)
with open('config.json', 'w') as json_file:
json.dump(configuration, json_file)
14.19.7. 7.将JSON转换为YAML¶
为了完整起见，我们也反过来：将JSON转换为YAML
config.json
{
"rest": {
"url": "https://example.org/primenumbers/v1",
"port": 8443
},
"prime_numbers": [
2,
3,
5,
7,
11,
13,
]
}
json-to-yaml.py
import yaml
import json
with open('config.json', 'r') as file:
configuration = json.load(file)
with open('config.yaml', 'w') as yaml_file:
yaml.dump(configuration, yaml_file)
with open('config.yaml', 'r') as yaml_file:
print(yaml_file.read())