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How to use Python to parse toml configuration files
- 王林forward
- 2023-05-21 11:20:041173browse
Give an example
With ini and yaml, I believe toml is also very simple to learn. Let’s look at an example directly.
import toml
config = """
title = "toml 小栗子"
[owner]
name = "古明地觉"
age = 17
place = "东方地灵殿"
nickname = ["小五", "少女觉", "觉大人"]
[database]
host = "127.0.0.1"
port = 5432
username = "satori"
password = "123456"
echo = true
[server]
[server.v1]
api = "1.1"
enable = false
[server.v2]
api = "1.2"
enable = true
[client]
client = [
["socket", "webservice"],
[5555]
]
address = [
"xxxx",
"yyyy"
]
"""
# loads：从字符串加载
# load：从文件加载
# dumps：生成 toml 格式字符串
# dump：生成 toml 格式字符串并写入文件中
data = toml.loads(config)
print(data)
"""
{
'title': 'toml 小栗子',
'owner': {'name': '古明地觉',
'age': 17,
'place': '东方地灵殿',
'nickname': ['小五', '少女觉', '觉大人']},
'database': {'host': '127.0.0.1',
'port': 5432,
'username': 'satori',
'password': '123456',
'echo': True},
'server': {'v1': {'api': '1.1', 'enable': False},
'v2': {'api': '1.2', 'enable': True}},
'client': {'client': [['socket', 'webservice'], [5555]],
'address': ['xxxx', 'yyyy']}
}
"""toml is configured in the form of var = value, and there are also sections similar to ini. Each section is a key in the dictionary, and the key also corresponds to a dictionary. Due to the lack of section, we need to note the initial title, so it is a separate key.
Another point is that toml supports nesting. We see server.v1, which means v1 is a key in the dictionary corresponding to server, and the value corresponding to v1 is still a dictionary.
toml has become simpler, and it is written very much like Python. It has the following characteristics:
toml files are case-sensitive;
toml files must be Valid UTF-8 encoded Unicode document;
The whitespace character of the toml file should be Tab or space;
The newline of the toml file should be LF or CRLF;
Then we Let’s introduce the data structure of toml.
Comments
toml uses # to represent comments. For example:
# 这是注释 key = "value" # 也是注释
You can parse it to see what you will get. Spoiler: you will get only one key-value pair. dictionary.
Key-value pair
The basic block is a key-value pair, with the key name on the left side of the equal sign and the value on the right side, while ignoring the blank TOML around the key name and key value. document. In addition, the key, equal sign, and value must be on the same line (although some values can span multiple lines).
key = "value"
Key names can appear in the form of bare keys, quoted keys, or dot-delimited keys. Bare keys are only allowed to contain ASCII characters, numbers, underscores, and hyphens.
import toml
config = """
key = "value"
bare_key = "value"
bare-key = "value"
# 1234 会被当成字符串
1234 = "value"
"""
data = toml.loads(config)
print(data)
"""
{'key': 'value',
'bare_key': 'value',
'bare-key': 'value',
'1234': 'value'}
"""If it is not a bare key, it must be enclosed in quotation marks, but at this time we are also supported to use a wider range of key names, but except for special scenarios, using bare keys is the best practice.
import toml
config = """
"127.0.0.1" = "value"
"character encoding" = "value"
"ʎǝʞ" = "value"
'key2' = "value"
'quoted "value"' = "value"
"""
data = toml.loads(config)
print(data)
"""
{'127.0.0.1': 'value',
'character encoding': 'value',
'ʎǝʞ': 'value',
'key2': 'value',
'quoted "value"': 'value'}
"""Note: Bare keys cannot be empty, but empty quote keys are allowed (although not recommended).
= "没有键名" # 错误 "" = "空" # 正确但不鼓励 '' = '空' # 正确但不鼓励
Then there is the dot-separated key, which is a series of bare keys or quoted keys connected by dots, which allows us to put similar attributes together:
import toml
config = """
name = "橙子"
physical.color = "橙色"
physical.shape = "圆形"
site."google.com" = true
site.google.com = true
a.b.c.d = 123
"""
data = toml.loads(config)
print(data)
"""
{
'name': '橙子',
'physical': {'color': '橙色',
'shape': '圆形'},
'site': {'google.com': True,
'google': {'com': True}},
'a': {'b': {'c': {'d': 123}}}
}
"""We see this dot-separated key The characters are good, the nested structure is automatically implemented, and the white space around the dot separator will be ignored.
fruit.name = "香蕉" # 这是最佳实践 fruit. color = "黄色" # 等同于 fruit.color fruit . flavor = "香蕉" # 等同于 fruit.flavor
Note: It is not possible to define the same key multiple times.
import toml
config = """
# name 和 "name" 是等价的
name = "古明地觉"
"name" = "古明地恋"
"""
try:
data = toml.loads(config)
except toml.decoder.TomlDecodeError as e:
print(e)
"""
Duplicate keys! (line 4 column 1 char 36)
"""The same is true for dot-delimited keys. As long as a key has not been directly defined, we can still assign values to it and its subordinate key names.
import toml
config = """
fruit.apple.smooth = true# 此时可以继续操作 fruit、fruit.apple，它们都是字典
# 给 fruit 这个字典加一个 key
fruit.orange = 2
# 给 fruit.apple 加一个 key
fruit.apple.color = "red"
"""
data = toml.loads(config)
print(data)
"""
{
'fruit': {'apple': {'smooth': True,
'color': 'red'},
'orange': 2}
}
"""But the following operation is not possible:
# 将 fruit.apple 的值定义为一个整数
fruit.apple = 1
# 但接下来就不合法了，因为整数不能变成字典
fruit.apple.smooth = true
# 如果我们设置 fruit.apple = {}，那么第二个赋值是可以的
# 没错，我们可以通过 {} 直接创建一个字典As you can see, it is really like Python. Then let’s talk about a special case:
import toml
config = """
3.14 = "pi"
"3.14" = "pi"
"""
data = toml.loads(config)
print(data)
"""
{'3': {'14': 'pi'}, '3.14': 'pi'}
"""If the key is a floating point number, it needs to be enclosed in quotes, otherwise it will be interpreted as a dot-delimited key.
After reading the keys, let’s look at the values. In fact, for toml, the values are much simpler than the keys.
String
There are four ways to represent strings: basic, multi-line basic, literal, and multi-line literal.
1) The base string is wrapped in quotes, and any Unicode character can be used, except those that must be escaped.
import toml
config = """
str = '我是一个字符串，"你可以把我引起来"'
"""
data = toml.loads(config)
print(data)
"""
{'str': '我是一个字符串，"你可以把我引起来"'}
"""Multi-line strings can be enclosed in three quotes and can contain newlines. However, it should be noted that the first newline after the opening quotation mark will be removed, and other spaces and newlines will be retained.
import toml
config = """
str = '''
玫瑰是红色的
紫罗兰是蓝色的
'''
"""
data = toml.loads(config)
print(data)
"""
{'str': '玫瑰是红色的\n紫罗兰是蓝色的\n'}
"""The quotation marks here can be double quotation marks or single quotation marks.
Integers
Integers are pure numbers. Positive numbers can be prefixed with a plus sign, and negative numbers can be prefixed with a minus sign.
import toml
config = """
int1 = +99
int2 = 42
int3 = 0
int4 = -17
# 对于大数，可以在数字之间用下划线来增强可读性
# 每个下划线两侧必须至少有一个数字。
int5 = 1_000
int6 = 5_349_221
int7 = 53_49_221 # 印度记数体系分组
int8 = 1_2_3_4_5 # 无误但不鼓励
"""
data = toml.loads(config)
print(data)
"""
{'int1': 99,
'int2': 42,
'int3': 0,
'int4': -17,
'int5': 1000,
'int6': 5349221,
'int7': 5349221,
'int8': 12345}
"""But note: Numbers cannot start with zero, except 0 itself. Unprefixed zero, -0, and 0 are equivalent. Nonnegative integer values can also be represented in hexadecimal, octal, or binary.
# 带有 `0x` 前缀的十六进制，大小写均可 hex1 = 0xDEADBEEF hex2 = 0xdeadbeef hex3 = 0xdead_beef # 带有 `0o` 前缀的八进制 oct1 = 0o01234567 oct2 = 0o755 # 对于表示 Unix 文件权限很有用 # 带有 `0b` 前缀的二进制 bin1 = 0b11010110
Floating point number
A floating point number can be composed of an integer part and a decimal part, or it can also be composed of an exponent part. The integer and fractional parts follow the same rules as for decimal integer values. If there is both a decimal part and an exponent part, the decimal part must come before the exponent part.
import toml
config = """
# 小数
flt1 = +1.0
flt2 = 3.1415
flt3 = -0.01
# 指数
flt4 = 5e+22
flt5 = 1e06
flt6 = -2E-2
flt7 = 6.626e-34
"""
data = toml.loads(config)
print(data)
"""
{'flt1': 1.0,
'flt2': 3.1415,
'flt3': -0.01,
'flt4': 5e+22,
'flt5': 1000000.0,
'flt6': -0.02,
'flt7': 6.626e-34}
"""The decimal part is a decimal point followed by one or more digits, and an exponent part is an E (either upper or lower case) followed by an integer part (follows the same rules as decimal integer values, but can contain leading zeros ). The decimal point, if used, must be immediately adjacent to at least one digit on each side.
# 非法的浮点数 invalid_float_1 = .7 invalid_float_2 = 7. invalid_float_3 = 3.e+20
Similar to integers, underscores can be used to enhance readability. Each underscore must be surrounded by at least one digit.
flt8 = 224_617.445_991_228
Floating point values -0.0 and 0.0 are valid and should comply with IEEE 754. Special floating point values can also be represented:
# 无穷 sf1 = inf # 正无穷 sf2 = +inf # 正无穷 sf3 = -inf # 负无穷 # 非数 sf4 = nan # 是对应信号非数码还是静默非数码，取决于实现 sf5 = +nan # 等同于 `nan` sf6 = -nan # 正确，实际码取决于实现
Boolean values
Boolean values are just like that, but in lowercase.
bool1 = true bool2 = false
Date
Can be an ordinary datetime, or a date following ISO-8859-1 format.
import toml
config = """
dt1 = 2020-01-01T12:33:22+00:00
dt2 = 2020-11-12 12:11:33
dt3 = 2020-11-23
"""
data = toml.loads(config)
print(data)
"""
{'dt1': datetime.datetime(2020, 1, 1, 12, 33, 22, tzinfo=...),
'dt2': datetime.datetime(2020, 11, 12, 12, 11, 33),
'dt3': datetime.date(2020, 11, 23)}
"""Array
The syntax is similar to Python's list:
import toml
config = """
# 每个数组里面的元素类型要一致
integers = [1, 2, 3]
colors = ["红", "黄", "绿"]
nested_array_of_ints = [[1, 2], [3, 4, 5]]
nested_mixed_array = [[1, 2], ["a", "b", "c"]]
numbers = [0.1, 0.2, 0.5]
"""
data = toml.loads(config)
print(data)
"""
{'colors': ['红', '黄', '绿'],
'integers': [1, 2, 3],
'nested_array_of_ints': [[1, 2], [3, 4, 5]],
'nested_mixed_array': [[1, 2], ['a', 'b', 'c']],
'numbers': [0.1, 0.2, 0.5]}
"""The array can span lines, and there can be a terminal comma (also called a trailing comma) after the last value of the array.
import toml
config = """
integers2 = [
1, 2, 3
]
integers3 = [
1,
2, # 这是可以的
]
"""
data = toml.loads(config)
print(data)
"""
{'integers2': [1, 2, 3], 'integers3': [1, 2]}
"""Table
Table, you can think of it as a section of ini.
import toml
config = """
# 表名的定义规则与键名相同
# 解析之后得到的大字典中就有 "table-1" 这个 key
# 并且其 value 也是一个表，在它下方
# 直至下一个表头或文件结束，都是这个表内部的键值对
[table-1]
key1 = "some string"
key2 = 123
[table-2]
key1 = "another string"
key2 = 456
"""
data = toml.loads(config)
print(data)
"""
{'table-1': {'key1': 'some string', 'key2': 123},
'table-2': {'key1': 'another string', 'key2': 456}}
"""But we have implemented a structure similar to this before, yes, it is the dot separator:
import toml
config = """
# 所以 other-table-1 和 table-1 是等价的
# other-table-2 和 table-2 是等价的
other-table-1.key1 = "some string"
other-table-1.key2 = 123
other-table-2.key1 = "another string"
other-table-2.key2 = 456
[table-1]
key1 = "some string"
key2 = 123
[table-2]
key1 = "another string"
key2 = 456
"""
data = toml.loads(config)
print(data)
"""
{'other-table-1': {'key1': 'some string', 'key2': 123},
'other-table-2': {'key1': 'another string', 'key2': 456},
'table-1': {'key1': 'some string', 'key2': 123},
'table-2': {'key1': 'another string', 'key2': 456}}
"""不过注意：我们必须要把 other-table-1 和 other-table-2 定义在上面，如果我们定义在下面看看会有什么后果：
import toml
config = """
[table-1]
key1 = "some string"
key2 = 123
[table-2]
key1 = "another string"
key2 = 456
other-table-1.key1 = "some string"
other-table-1.key2 = 123
other-table-2.key1 = "another string"
other-table-2.key2 = 456
"""
data = toml.loads(config)
print(data)
"""
{
'table-1': {'key1': 'some string', 'key2': 123},
'table-2': {'key1': 'another string',
'key2': 456,
'other-table-1': {'key1': 'some string',
'key2': 123},
'other-table-2': {'key1': 'another string',
'key2': 456}}
}
"""你可能已经猜到了，它们被视为了“table-2”对应的字典键。此外我们还可以将上面两种方式结合起来：
import toml
config = """
# [] 里面的不再是一个普通的键，而是点分隔键
# 另外键名周围的空格会被忽略，但是最好不要有
[dog . "tater.man"]
type.name = "哈巴狗"
"""
data = toml.loads(config)
print(data)
"""
{
'dog': {'tater.man': {'type': {'name': '哈巴狗'}}}
}
"""表的里面也是可以没有键值对的：
import toml
config = """
[x.y.z.w.a.n]
[x.m]
[x.n]
[x]
a.b.c = "xxx"
"""
data = toml.loads(config)
print(data)
"""
{'x':
{
'a': {'b': {'c': 'xxx'}},
'm': {},
'n': {},
'y': {'z': {'w': {'a': {'n': {}}}}}
}
}
"""总的来说还是蛮强大的，但是要注意：不能重复定义。
行内表
行内表提供了一种更为紧凑的语法来表示表，因为上面每一个键值对都需要单独写一行，比如：
[table1]
a = 1
b = 2
c = 3
# 最终可以得到
# {'table1': {'a': 1, 'b': 2, 'c': 3}}但是除了上面的表达方式之外，我们还可以采用行内表：
import toml
config = """
# 和 Python 字典的表示方式略有不同
# 并且也支持多种 key
table1 = {a = 1, b = "二", c.a = "3"}
table2 = {c."b c".d = "4"}
"""
data = toml.loads(config)
print(data)
"""
{
'table1': {'a': 1, 'b': '二', 'c': {'a': '3'}},
'table2': {'c': {'b c': {'d': '4'}}}
}
"""表数组
然后来看看数组和表的结合：
import toml
config = """
[name1]
girl = "古明地觉"
[[name2]]
girl = "古明地恋"
[name3]
[[name4]]
"""
data = toml.loads(config)
print(data)
"""
{'name1': {'girl': '古明地觉'},
'name2': [{'girl': '古明地恋'}],
'name3': {},
'name4': [{}]}
"""当使用 [[]] 的时候，相当于在 [] 的基础上套上一层列表。任何对表数组的引用都会指向该数组中最近定义的表元素，这使得我们能够在最近的表内定义子表甚至子表数组。
我们再举个更复杂的例子：
import toml
config = """
[[fruits]]
name = "苹果"
# 会操作 [] 里面最近定义的 {}
[fruits.physical]
color = "红色"
shape = "圆形"
[[fruits.varieties]] # 嵌套表数组
name = "蛇果"
[[fruits.varieties]]
name = "澳洲青苹"
[[fruits]]
name = "香蕉"
[[fruits.varieties]]
name = "车前草"
"""
data = toml.loads(config)
print(data)
"""
{
'fruits':
[
{
'name': '苹果',
'physical': {'color': '红色',
'shape': '圆形'},
'varieties': [{'name': '蛇果'},
{'name': '澳洲青苹'}]
},
{
'name': '香蕉',
'varieties': [{'name': '车前草'}]
}
]
}
"""很明显这种定义不是很常用，配置文件应该要非常直观才对，但这已经不是很好理解了。
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