基本格式
- 用空格缩进, 不能用tab
- 用#标记注释
- 列表: 用短划(-)标记元素
- 映射: 用冒号(:)分隔key, value. 如果写在一行, 需要用逗号分隔并前后加花括号
- 字符串: 不加引号, 加单引号或者加双引号都可以, 加双引号时可以使用开头的转义字符
- 多行字符串可以用 | 或 > 符号, 紧接着换行符
- 重复的节点, 可以用 & 标识, 并用 * 来引用
基本元素
列表
# 普通
- Casablanca
- North by Northwest
- The Man Who Wasn't There
# 单行
[milk, pumpkin pie, eggs, juice]
men: [John Smith, Bill Jones]
women:
- Mary Smith
- Susan Williams
映射
# Indented Block
name: John Smith
age: 33
# Inline Block
{name: John Smith, age: 33}
- {name: John Smith, age: 33}
- name: Mary Smith
age: 27
多行字符串
data: |
There once was a short man from Ealing
Who got on a bus to Darjeeling
It said on the door
"Please don't spit on the floor"
So he carefully spat on the ceiling
data: >
Wrapped text
will be folded
into a single
paragraph
Blank lines denote
paragraph breaks
指定类型
a: 123 # an integer
b: "123" # a string, disambiguated by quotes
c: 123.0 # a float
d: !!float 123 # also a float via explicit data type prefixed by (!!)
e: !!str 123 # a string, disambiguated by explicit type
f: !!str Yes # a string via explicit type
g: Yes # a boolean True (yaml1.1), string "Yes" (yaml1.2)
h: Yes we have No bananas # a string, "Yes" and "No" disambiguated by context.
picture: !!binary |
R0lGODdhDQAIAIAAAAAAANn
Z2SwAAAAADQAIAAACF4SDGQ
ar3xxbJ9p0qa7R0YxwzaFME
1IAADs=
myObject: !myClass { name: Joe, age: 15 }
另一篇简明的介绍, from https://learnxinyminutes.com/docs/yaml/
--- # document start
# Comments in YAML look like this.
################
# SCALAR TYPES #
################
# Our root object (which continues for the entire document) will be a map,
# which is equivalent to a dictionary, hash or object in other languages.
key: value
another_key: Another value goes here.
a_number_value: 100
scientific_notation: 1e+12
# The number 1 will be interpreted as a number, not a boolean. if you want
# it to be interpreted as a boolean, use true
boolean: true
null_value: null
key with spaces: value
# Notice that strings don't need to be quoted. However, they can be.
however: 'A string, enclosed in quotes.'
'Keys can be quoted too.': "Useful if you want to put a ':' in your key."
single quotes: 'have ''one'' escape pattern'
double quotes: "have many: ", , , u263A, x0dx0a ==
, and more."
# Multiple-line strings can be written either as a 'literal block' (using |),
# or a 'folded block' (using '>').
literal_block: |
This entire block of text will be the value of the 'literal_block' key,
with line breaks being preserved.
The literal continues until de-dented, and the leading indentation is
stripped.
Any lines that are 'more-indented' keep the rest of their indentation -
these lines will be indented by 4 spaces.
folded_style: >
This entire block of text will be the value of 'folded_style', but this
time, all newlines will be replaced with a single space.
Blank lines, like above, are converted to a newline character.
'More-indented' lines keep their newlines, too -
this text will appear over two lines.
####################
# COLLECTION TYPES #
####################
# Nesting uses indentation. 2 space indent is preferred (but not required).
a_nested_map:
key: value
another_key: Another Value
another_nested_map:
hello: hello
# Maps don't have to have string keys.
0.25: a float key
# Keys can also be complex, like multi-line objects
# We use ? followed by a space to indicate the start of a complex key.
? |
This is a key
that has multiple lines
: and this is its value
# YAML also allows mapping between sequences with the complex key syntax
# Some language parsers might complain
# An example
? - Manchester United
- Real Madrid
: [2001-01-01, 2002-02-02]
# Sequences (equivalent to lists or arrays) look like this
# (note that the '-' counts as indentation):
a_sequence:
- Item 1
- Item 2
- 0.5 # sequences can contain disparate types.
- Item 4
- key: value
another_key: another_value
-
- This is a sequence
- inside another sequence
- - - Nested sequence indicators
- can be collapsed
# Since YAML is a superset of JSON, you can also write JSON-style maps and
# sequences:
json_map: {"key": "value"}
json_seq: [3, 2, 1, "takeoff"]
and quotes are optional: {key: [3, 2, 1, takeoff]}
#######################
# EXTRA YAML FEATURES #
#######################
# YAML also has a handy feature called 'anchors', which let you easily duplicate
# content across your document. Both of these keys will have the same value:
anchored_content: &anchor_name This string will appear as the value of two keys.
other_anchor: *anchor_name
# Anchors can be used to duplicate/inherit properties
base: &base
name: Everyone has same name
# The regexp << is called Merge Key Language-Independent Type. It is is used to
# indicate that all the keys of one or more specified maps should be inserted
# into the current map.
foo: &foo
<<: *base
age: 10
bar: &bar
<<: *base
age: 20
# foo and bar would also have name: Everyone has same name
# YAML also has tags, which you can use to explicitly declare types.
explicit_string: !!str 0.5
# Some parsers implement language specific tags, like this one for Python's
# complex number type.
python_complex_number: !!python/complex 1+2j
# We can also use yaml complex keys with language specific tags
? !!python/tuple [5, 7]
: Fifty Seven
# Would be {(5, 7): 'Fifty Seven'} in Python
####################
# EXTRA YAML TYPES #
####################
# Strings and numbers aren't the only scalars that YAML can understand.
# ISO-formatted date and datetime literals are also parsed.
datetime: 2001-12-15T02:59:43.1Z
datetime_with_spaces: 2001-12-14 21:59:43.10 -5
date: 2002-12-14
# The !!binary tag indicates that a string is actually a base64-encoded
# representation of a binary blob.
gif_file: !!binary |
R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5
OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+
+f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC
AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs=
# YAML also has a set type, which looks like this:
set:
? item1
? item2
? item3
or: {item1, item2, item3}
# Sets are just maps with null values; the above is equivalent to:
set2:
item1: null
item2: null
item3: null
... # document end