Pydantic field validation against Enum name

Question

I have an Enum:

class DataType(Enum):
    TIMESTAMP = MyClass("ts")
    DATETIME = MyClass("dt")
    DATE = MyClass("date")

and a Pydantic Model with a field of the type of that Enum:

class Aggregation(BaseModel):
    field_data_type: DataType

Is there a convenient way to tell Pydantic to validate the Model field against the names of the enum rather than the values? i.e., to be able to build this Model:

agg = Aggregation(field_data_type="TIMESTAMP")

I don't know what exactly your case is, but I would say that creating 2 enums instead of 1 in a situation like this is a much better practice. It could be something like: class DataType(Enum): TIMESTAMP = "TIMESTAMP" and class DataTypeAPI(Enum): TIMESTAMP = "ts" — Victor Egiazarian
– Victor Egiazarian, Commented Jul 2, 2024 at 11:06
but I have 20 enum names, it will create unnecessary code duplication — Onca
– Onca, Commented Jul 2, 2024 at 15:58
These enums have different purposes, this is not a duplication, but a way to make your enums responsible for one thing. Any wrappers over enumerations will only confuse other developers, even if they take up a few less lines of code. — Victor Egiazarian
– Victor Egiazarian, Commented Jul 2, 2024 at 16:05
Moreover, you increase the chance of an error appearing. Of course, this is just a recommendation and the final decision is yours! — Victor Egiazarian
– Victor Egiazarian, Commented Jul 2, 2024 at 16:07

r_2009 · Accepted Answer · 2024-07-02 01:19:05Z

1

You can use the built-in functionality of Enum to accomplish this:

agg = Aggregation(field_data_type=DataType["TIMESTAMP"])

You can wrap this in a function and then create a new annotated type that calls it:

def convert_to_data_type(s: str):
    return DataType[s]

StrDataType = Annotated[str, AfterValidator(convert_to_data_type)]

class Aggregation(BaseModel):
    field_data_type: StrDataType

agg = Aggregation(field_data_type="TIMESTAMP")

answered Jul 2, 2024 at 1:19

r_2009

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