'NoneType' object is not subscriptable when serializing fields that do not belong to the database is None

[dinghao-8]

class UserConfig(SQLModel, table=True):
    __tablename__ = "user_config"
    id: Optional[int] = Field(default=None, primary_key=True)
    user_id: Optional[int]
    _user_name: str = '' #---> not in database fields

    @property
    def user_name(self):
        return self._user_name

    @user_name.setter
    def user_name(self, user_name):
        self._user_name = user_name


class UserConfigSchema(Schema):
    user_id = fields.Int() 
    user_name = fields.Str(allow_none= True)
    id = fields.Int()

    class Meta:
        model = UserConfig
        unknown = EXCLUDE

user_config_schema.dumps(user_config) # --->issue NoneType .....
what i should to do in that time.
Please confirm whether it needs to be repaired or if there are any solutions other than @post_dump

[dinghao-8]

@post_dump also not work

[Flargebla]

Can you either post a complete script showcasing the issue or provide more clarity on the problem? It sounds like when you try to serialize (via dumps) a UserConfig instance, you are receiving a NoneType return. I'd like to try and recreate the issue to help debug, but I might be missing something.

Here is the complete script I run, and the resulting output:

from marshmallow import Schema, fields, EXCLUDE
from sqlmodel import SQLModel, Field
from typing import Optional

class UserConfig(SQLModel, table=True):
    __tablename__ = "user_config"
    id: Optional[int] = Field(default=None, primary_key=True)
    user_id: Optional[int]
    _user_name: str = '' #---> not in database fields

    @property
    def user_name(self):
        return self._user_name

    @user_name.setter
    def user_name(self, user_name):
        self._user_name = user_name


class UserConfigSchema(Schema):
    user_id = fields.Int() 
    user_name = fields.Str(allow_none=True)
    id = fields.Int()

    class Meta:
        model = UserConfig
        unknown = EXCLUDE

# Presumed precursor code:
user_config_schema = UserConfigSchema()
user_config = UserConfig()
#user_config.user_name = "testname"
#user_config.user_name = None

# Problematic line:
res = user_config_schema.dumps(user_config) # --->issue NoneType .....
print(res)

When I run this, I get the following string value as a return from dumps:

{"user_id": null, "user_name": "", "id": null}

[dinghao-8]

i`m so sorry, i forget what happended at that time. - -!)