从字符串数组初始化pydantic Literal

debugcn 发表于 Dev

西尔维奥·梅西（Silvio Messenger）

我想从一系列字符串中初始化化dan字面量

from typing import Literal
from pydantic import BaseModel

CLASS_NAME_VALUES = ["primary", "secondary", "success", "danger", "warning", "info", "dark"]
ICON_NAME_VALUES = ["electricity.svg", "water.svg",
                    "internet.svg", "naturalGas.svg", "noCategory.svg"]

class CategoryRequest(BaseModel):
    class_name: Literal[CLASS_NAME_VALUES]
    icon_name: Literal[ICON_NAME_VALUES]

但我收到以下错误

  File "pydantic/main.py", line 252, in pydantic.main.ModelMetaclass.__new__
  File "pydantic/fields.py", line 309, in pydantic.fields.ModelField.infer
  File "pydantic/fields.py", line 271, in pydantic.fields.ModelField.__init__
  File "pydantic/fields.py", line 351, in pydantic.fields.ModelField.prepare
  File "pydantic/fields.py", line 529, in pydantic.fields.ModelField.populate_validators
  File "pydantic/validators.py", line 566, in find_validators
  File "pydantic/validators.py", line 410, in pydantic.validators.make_literal_validator
TypeError: unhashable type: 'list'

有什么建议吗？

alex_noname

在运行时，允许使用任意值作为类型参数Literal[...]，但类型检查器可能会施加限制。例如，mypy仅允许一个或更多个文字bool，int，str，bytes，enum的值，None和别名到其他Literal类型。例如，Literal[3 + 4]或List[(3, 4)]不允许。

至于pydantic，它允许在中使用可哈希类型的值Literal，如tuple。例如，可以使用以下示例重写您的示例tuple：

from typing import Literal
from pydantic import BaseModel

CLASS_NAME_VALUES = ("primary", "secondary", "success", "danger", "warning", "info", "dark")
ICON_NAME_VALUES = ("electricity.svg", "water.svg",
                    "internet.svg", "naturalGas.svg", "noCategory.svg")


class CategoryRequest(BaseModel):
    class_name: Literal[CLASS_NAME_VALUES]
    icon_name: Literal[ICON_NAME_VALUES]

但是我强烈建议您不要使用这种语法，而应遵循规范的语法，类型检查器也允许这样做：

CLASS_NAME_VALUES = Literal["primary", "secondary", "success", "danger", "warning", "info", "dark"]
ICON_NAME_VALUES = Literal["electricity.svg", "water.svg",
                    "internet.svg", "naturalGas.svg", "noCategory.svg"]


class CategoryRequest(BaseModel):
    class_name: CLASS_NAME_VALUES
    icon_name: ICON_NAME_VALUES

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