[BUG] Variables with annotation of 'typing.Literal' causes a panic about sqlmodel

[shifqu]

I also encountered this issue and ended up implementing the check for a Literal at the beginning of get_sqlachemy_type.

field_type = field.type_
if is_literal_type(field_type):
    # Try to get the single type of the literal, error otherwise
    types = list({type(x) for x in get_args(field_type)})
    if len(types) != 1:
        raise RuntimeError("Cannot map a literal with multiple types to a sql type.")
    field_type = types[0]

To make this work you would still need to import get_args and is_literal_type, also refactor each field.type_ call to field_type

The problem with this solution is that it is specifically for a Literal. So, not sure if this will be immediately accepted to be implemented. Happy to make this into a PR if needed.

I eventually stopped using Literal, and chose for an Enum, which works out of the box :)

In your case:

from enum import Enum

class NameEnum(str, Enum):
    FASTAPI = "fastapi"
    SQLMODEL = "sqlmodel"


class Cool(SQLModel, table=True):
    name: NameEnum

[data-djinn]

@shifqu this solved my problem, thanks!

[sietse]

EDIT: See pydantic/pydantic#5821 (comment) for the main issue and a list of workarounds.

I'm deleting the rest of my comment: all its information is present in the linked thread.

[Cielquan]

I have the same issue and went with the enum solution. But the Literal approach would be still worth adding I guess, for the future to open up the possibilities.

[Cielquan]

I encountered an issue with the enum approach (see #406) where the validation for the field with the enum values silently passes for invalid values.

[sasilver75]

I have this issue when trying to use a Discriminated Union on a SQLModel a la Pydantic

[PaleNeutron]

In your case:

from enum import Enum

class NameEnum(str, Enum):
    FASTAPI = "fastapi"
    SQLMODEL = "sqlmodel"


class Cool(SQLModel, table=True):
    name: NameEnum

I have to emphasis this code actually write FASTAPI uppercase, the enum key into database, not "fastapi" lower case, the value.