How to Fix SQLAlchemy InvalidRequestError: Failed to Locate Relationship Class Name in Model Definition

[MuttakinHasib]

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Example Code

# notebook/model.py

from typing import List, TYPE_CHECKING

from sqlmodel import SQLModel, Field, Column, JSON, Relationship
from notebook.common.entity import BaseEntity
from notebook.common.status import Status
if TYPE_CHECKING:
    from notebook.sources.model import Source
    from notebook.topics.model import Topic

class NotebookBase(SQLModel):
    name: str

class Notebook(BaseEntity, NotebookBase, table=True):
    status: Status = Field(default=Status.CURRENT)
    configs: dict[str, str] = Field(default_factory=dict, sa_column=Column(JSON))
    sources: List["Source"] = Relationship(back_populates="notebook")
    topics: List["Topic"] = Relationship(back_populates="notebook")

# topics/model.py

import uuid
from typing import Optional, TYPE_CHECKING
from sqlmodel import SQLModel, Field, Relationship
from notebook.common.entity import BaseEntity
from notebook.common.status import Status

if TYPE_CHECKING:
    from notebook.notebooks.model import Notebook


class TopicBase(SQLModel):
    name: str
    data: Optional[str]

class Topic(BaseEntity, TopicBase, table=True):
    status: Status = Field(default=Status.CURRENT)
    notebook_id: uuid.UUID = Field(foreign_key='notebook.id', nullable=False, ondelete="CASCADE")
    notebook: Optional["Notebook"] = Relationship(back_populates="topics")

# sources/model.py

import uuid
from typing import Optional, TYPE_CHECKING
from sqlmodel import SQLModel, Field, Column, JSON, Relationship

from notebook.common.entity import BaseEntity
from notebook.common.status import Status

if TYPE_CHECKING:
    from notebook.notebooks.model import Notebook

class SourceBase(SQLModel):
    data: Optional[str]
    type: Optional[str]
    status: Status = Field(default=Status.CURRENT)

class File(SQLModel):
    url: str
    mime: str
    filename: str

    def to_dict(self) -> dict:
        return {"url": self.url, "mime": self.mime, "filename": self.filename}

    @classmethod
    def from_dict(cls, data: dict) -> "File":
        return cls(**data)

class Source(BaseEntity, SourceBase, table=True):
    file: Optional[dict] = Field(sa_column=Column(JSON))
    notebook_id: uuid.UUID = Field(foreign_key='notebook.id', nullable=False, ondelete="CASCADE")
    notebook: Optional["Notebook"] = Relationship(back_populates="sources")


# create project:
@router.post("/", response_model=Notebook)
async def create_notebook(notebook: NotebookBase, session: SessionDependency):
    db_notebook = Notebook.model_validate(notebook)
    session.add(db_notebook)
    session.commit()
    session.refresh(db_notebook)
    return db_notebook

Description

In my application, I have a Notebook table, with each notebook containing multiple Sources and Topics. I've established the relationships in my model (example code provided). However, when I make a POST request to create a notebook, I encounter the following error:

sqlalchemy.exc.InvalidRequestError: When initializing mapper Mapper[Notebook(notebook)], expression 'Source' failed to locate a name ('Source'). If this is a class name, consider adding this relationship() to the <class 'notebook.notebooks.model.Notebook'> class after both dependent classes have been defined.

@tiangolo, could you please help me resolve this issue?
Thank you!

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.22

Python Version

3.11

Additional Context

No response