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Non-sqlalchemy types unable to be defined in base data models #469
Description
First Check
- I added a very descriptive title to this issue.
- I used the GitHub search to find a similar issue and didn't find it.
- I searched the SQLModel documentation, with the integrated search.
- I already searched in Google "How to X in SQLModel" and didn't find any information.
- I already read and followed all the tutorial in the docs and didn't find an answer.
- I already checked if it is not related to SQLModel but to Pydantic.
- I already checked if it is not related to SQLModel but to SQLAlchemy.
Commit to Help
- I commit to help with one of those options 👆
Example Code
#!/usr/bin/env python3
from typing import Optional, Any
import sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.mutable import MutableDict, MutableSet
from sqlalchemy.orm import sessionmaker
from sqlalchemy import JSON, Column
from sqlmodel import SQLModel, Field, create_engine, Relationship
Session = sessionmaker()
Base = declarative_base()
class BaseTrack(SQLModel):
title: str
class Track(BaseTrack, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
title: int
album_id: Optional[int] = Field(default=None, foreign_key="album.id")
album: "Album" = Relationship(back_populates="tracks")
class BaseAlbum(SQLModel):
tracks: list[BaseTrack]
class Album(BaseAlbum, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
tracks: Optional[list[Track]] = Relationship(back_populates="album")
engine = create_engine("sqlite:///:memory:")
Session.configure(bind=engine)
SQLModel.metadata.create_all(engine)
session = Session()
track = Track(id=1, title=2, album_id=1, album=Album(id=1))
session.add(track)
session.commit()Description
The above code gives the following error:
Traceback (most recent call last):
File "/home/jacob/src/Moe/test_custom.py", line 31, in <module>
class Album(BaseAlbum, table=True):
File "/home/jacob/src/Moe/.venv/lib/python3.9/site-packages/sqlmodel/main.py", line 293, in __new__
col = get_column_from_field(v)
File "/home/jacob/src/Moe/.venv/lib/python3.9/site-packages/sqlmodel/main.py", line 421, in get_column_from_field
sa_type = get_sqlachemy_type(field)
File "/home/jacob/src/Moe/.venv/lib/python3.9/site-packages/sqlmodel/main.py", line 414, in get_sqlachemy_type
raise ValueError(f"The field {field.name} has no matching SQLAlchemy type")
ValueError: The field tracks has no matching SQLAlchemy typeBecause I'm overriding tracks to be a column in my actual database class, this should not error.
Operating System
Linux
Operating System Details
No response
SQLModel Version
0.08
Python Version
3.9.13
Additional Context
Looks to have been caused by #18
Activity
antont commented on Oct 21, 2022
Why do you want to have the relationship in the base? I've simply omitted them from there, as inherit Base to the Create models, which are the POST data that the frontend uses to create objects. Then Read models have such definitions for the relationships that we wanna expose in the API.
jtpavlock commented on Oct 21, 2022
I'm using the base model to represent a subset of data useful for certain operations that don't require connection to a database or the entire model to be present.
tiangolo commented on Oct 21, 2022
Yep, you shouldn't do that. If a descendant of the base class is completely overriding the field, then it should probably not be there. In this particular case, it should certainly not be there on the base class.
You would have one field for the table model and another field for the class that inherits from base that needs the relationship.
If you want to avoid duplicating the field with relationships you would need a base for everything, and another "sub-base" only for data models (not tables) that includes the relationship.
github-actions commented on Nov 1, 2022
Assuming the original need was handled, this will be automatically closed now. But feel free to add more comments or create new issues or PRs.