Exception: Don't know how to convert the SQLAlchemy field: UUIDType

[Msordet]

Hi,

My app crashes with the following mapping:

#error
Exception: Don't know how to convert the SQLAlchemy field item.uuid_column (<class 'sqlalchemy.sql.schema.Column'>)

# model
from sqlalchemy_utils import UUIDType

class Item(Base):
    uuid_column = Column(UUIDType(binary=False), nullable=False, unique=True)

# schema
from graphene_sqlalchemy import SQLAlchemyObjectType

class ItemNode(SQLAlchemyObjectType):
    class Meta:
        model = Item

I tried to put this in my schema file to no avail:

from sqlalchemy_utils import UUIDType
from graphene_sqlalchemy.converter import get_column_doc, is_column_nullable, convert_sqlalchemy_type

@convert_sqlalchemy_type.register(UUIDType)
def convert_column_to_string(type, column, registry=None):
    return graphene.String(description=get_column_doc(column), required=not (is_column_nullable(column)))

I checked the following issues/PR but I don't get it: :/

• Support for Custom Column Types? #53
• Convert UUID Type failed #233
• Map pg's uuid to graphene's uuid #203

Can someone point me in the right direction with this?

[Msordet]

I found a solution by putting the convert_column_to_string right after the model declaration instead of in the schema file.
I don't really get why so if someone could explain, that'd be nice. :)

[jbvsmo]

This still doesn't work for me with the error:

Exception: NonNull could not have a mounted String() as inner type. Try with NonNull(String).

Trying with NonNull(String) give another error

AssertionError: Can only create NonNull of a Nullable GraphQLType

[jbvsmo]

The above error happens when I set primary_key=True on the column.
I don't see why an UUID could not be the primary_key, but seems like this is an issue with graphene-sqlalchemy treating as string, since the model works fine

uuid = Column(UUIDType, primary_key=True)

[calibodhi]

Any updates on this issue? I am trying to use a UUID as a primary key and having the same error as the original above. Many thanks 🙏

[rrobby86]

Using this custom SQLAlchemy type using UUID objects on Python side, on graphene 3.1.1 and graphene-sqlalchemy 3.0.0b3 (other versions may differ) I managed to get proper conversion to string without errors adding the following code before declaration of GraphQL schema (i.e. SQLAlchemyObjectType subclasses):

from graphene_sqlalchemy.converter import convert_sqlalchemy_type
from my.own.sub.package import GUID

@convert_sqlalchemy_type.register(GUID)
def convert_uuid_to_string(type, column, registry=None):
    return String

Using String(description=..., required=...) as suggested above was giving me an error NonNull could not have a mounted String() as inner type. Try with NonNull(String).

[github-actions]

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