field types

pydantic 尽可能的使用标准库类型（standard library types）来标注字段来提供一个平滑的学习曲线；不过它也实现了许多常用的类型（commonly used types）

你当然可以创造属于自己的类型（your own pydantic-compatible types）

标准库类型

• None, type(None) or Literal[None]

  • 只允许 None 值

• bool

  • 详见 Booleans

• int

  • pydantic 使用 int(v) 去将 v 强制转换成 int

• float

  • 同样地，float(v) 也会将 v 强制转换成 float

• str

  • str 原样接收
  • int float 和 Decimal 会被 str(v) 强制转换
  • bytes 和 bytearray 会用 v.decode() 强制转换
  • 继承自 str 的 enum 会被 v.value 强制转换
  • 其他的类型都会报错

• bytes

  • bytes 原样接收
  • bytearray 用 bytes(v) 转换
  • str 用 v.encode() 转换
  • int, float 和 Decimal 用 str(v).encode() 强制转换

• list

  允许 list, tuple, set, frozenset, deque, 或者生成器（generators）并且将其转换为 list

• tuple

  allows list, tuple, set, frozenset, deque, or generators and casts to a tuple; see typing.Tuple below for sub-type constraints

• dict

  dict(v) is used to attempt to convert a dictionary; see typing.Dict below for sub-type constraints

• set

  allows list, tuple, set, frozenset, deque, or generators and casts to a set; see typing.Set below for sub-type constraints

• frozenset

  allows list, tuple, set, frozenset, deque, or generators and casts to a frozen set; see typing.FrozenSet below for sub-type constraints

• deque

  allows list, tuple, set, frozenset, deque, or generators and casts to a deque; see typing.Deque below for sub-type constraints

• datetime.date

  see Datetime Types below for more detail on parsing and validation

• datetime.time

  see Datetime Types below for more detail on parsing and validation

• datetime.datetime

  see Datetime Types below for more detail on parsing and validation

• datetime.timedelta

  see Datetime Types below for more detail on parsing and validation

• typing.Any

  allows any value including None, thus an Any field is optional

• typing.Annotated

  allows wrapping another type with arbitrary metadata, as per PEP-593. The Annotated hint may contain a single call to the Field function, but otherwise the additional metadata is ignored and the root type is used.

• typing.TypeVar

  constrains the values allowed based on constraints or bound, see TypeVar

• typing.Union

  see Unions below for more detail on parsing and validation

• typing.Optional

  Optional[x] is simply short hand for Union[x, None]; see Unions below for more detail on parsing and validation and Required Fields for details about required fields that can receive None as a value.

• typing.List

• typing.Tuple

• subclass of typing.NamedTuple

  Same as tuple but instantiates with the given namedtuple and validates fields since they are annotated. See Annotated Types below for more detail on parsing and validation

• subclass of collections.namedtuple

  Same as subclass of typing.NamedTuple but all fields will have type Any since they are not annotated

• typing.Dict

  see Typing Iterables below for more detail on parsing and validation

• subclass of typing.TypedDict

  Same as dict but pydantic will validate the dictionary since keys are annotated. See Annotated Types below for more detail on parsing and validation

• typing.Set

  see Typing Iterables below for more detail on parsing and validation

• typing.FrozenSet

  see Typing Iterables below for more detail on parsing and validation

• typing.Deque

  see Typing Iterables below for more detail on parsing and validation

• typing.Sequence

  see Typing Iterables below for more detail on parsing and validation

• typing.Iterable

  this is reserved for iterables that shouldn’t be consumed. See Infinite Generators below for more detail on parsing and validation

• typing.Type

  see Type below for more detail on parsing and validation

• typing.Callable

  see Callable below for more detail on parsing and validation

• typing.Pattern

  will cause the input value to be passed to re.compile(v) to create a regex pattern

• ipaddress.IPv4Address

  simply uses the type itself for validation by passing the value to IPv4Address(v); see Pydantic Types for other custom IP address types

• ipaddress.IPv4Interface

  simply uses the type itself for validation by passing the value to IPv4Address(v); see Pydantic Types for other custom IP address types

• ipaddress.IPv4Network

  simply uses the type itself for validation by passing the value to IPv4Network(v); see Pydantic Types for other custom IP address types

• ipaddress.IPv6Address

  simply uses the type itself for validation by passing the value to IPv6Address(v); see Pydantic Types for other custom IP address types

• ipaddress.IPv6Interface

  simply uses the type itself for validation by passing the value to IPv6Interface(v); see Pydantic Types for other custom IP address types

• ipaddress.IPv6Network

  simply uses the type itself for validation by passing the value to IPv6Network(v); see Pydantic Types for other custom IP address types

• enum.Enum

  checks that the value is a valid Enum instance

• subclass of enum.Enum

  checks that the value is a valid member of the enum; see Enums and Choices for more details

• enum.IntEnum

  checks that the value is a valid IntEnum instance

• subclass of enum.IntEnum

  checks that the value is a valid member of the integer enum; see Enums and Choices for more details

• decimal.Decimal

  pydantic attempts to convert the value to a string, then passes the string to Decimal(v)

• pathlib.Path

  simply uses the type itself for validation by passing the value to Path(v); see Pydantic Types for other more strict path types

• uuid.UUID

  strings and bytes (converted to strings) are passed to UUID(v), with a fallback to UUID(bytes=v) for bytes and bytearray; see Pydantic Types for other stricter UUID types

• ByteSize

  converts a bytes string with units to bytes