• 1. introduction
• 2. 缩进
• 3. Key-Value pairs
• 4. list
• 5. 引用
• 6. corresponding json

1. introduction

YAML 的配置文件后缀为.yml，如：hello.yml

大小写敏感

#表示注释

2. 缩进

• 使用缩进表示层级关系
• 缩进不允许使用tab，只允许空格
• 缩进的空格数不重要，只要相同层级的元素左对齐即可
• there MUST be spaces between element parts.

3. Key-Value pairs

key: value

Name:Value, it is wrong，中间必须要有空格.

key: {child-key: value1, child-key2: value2}

key: 
    child-key: value1
    child-key2: value2

?  
    - complexkey1
    - complexkey2
:
    - complexvalue1
    - complexvalue2

examples:

intNumber: 299
binaryNumber: 0b1010_0111_0100_1010_1110    #二进制表示

floatNumber1: 3.14
floatNumber2: 6.8523015e+5  #可以使用科学计数法

quotedText: "some text description"     # " or '
moreQuotedtext: strings do not have to be quoted, but I prefer to do it=
multipleText:
    - newline
      newline2    #字符串可以拆成多行，每一行会被转化成一个空格
we can also have spaces in keys: and also in values

# TRUE, true, True, FALSE, false, False 都可以
boolean: true

# 日期只能用两种格式
date: 2018-02-17    # ISO 8601格式，即yyyy-MM-dd
datetime: 2018-02-17T15:02:31+08:00    # ISO 8601格式，时间和日期之间使用T连接，最后使用+代表时区

nullKeyValue1: null
nullKeyValue2: 'node'
nullKeyValue3: ~ 

4. list

key: [value1, value2]

key: 
 - value1
 - value2

# list + key-value
- name: John Doe
  occupation: gardener
- name: Lucy Black
  occupation: teacher

5. 引用

& 用来建立锚点，<< 表示合并到当前数据，* 用来引用锚点。

defaults: &defaults
  adapter:  postgres
  host:     localhost

development:
  database: myapp_development
  <<: *defaults

test:
  database: myapp_test
  <<: *defaults

相当于:

defaults:
  adapter:  postgres
  host:     localhost

development:
  database: myapp_development
  adapter:  postgres
  host:     localhost

test:
  database: myapp_test
  adapter:  postgres
  host:     localhost

下面是另一个例子:

list:
    - &showell Steve 
    - Clark 
    - Brian 
    - Oren 
    - *showell 

即

list: ['Steve', 'Clark', 'Brian', 'Oren', 'Steve']

6. corresponding json

languages:
  - Ruby
  - Perl
  - Python 
websites:
  YAML: yaml.org 
  Ruby: ruby-lang.org 
  Python: python.org 
  Perl: use.perl.org

转换为 json 为：

{ 
  languages: [ 'Ruby', 'Perl', 'Python'],
  websites: {
    YAML: 'yaml.org',
    Ruby: 'ruby-lang.org',
    Python: 'python.org',
    Perl: 'use.perl.org' 
  } 
}