Relationship problem "When initializing mapper"

[ericPavone]

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Example Code

class BaseEntity(SQLModel):
    """Class with base data from the entities"""

    id: int | None = Field(default=None, primary_key=True)
    data_creation: str
    data_udpate: str | None
    
    class Config:
        arbitrary_types_allowed = True



class Product(
    BaseEntity,
    table=True,
):
    """Class the products"""

    __tablename__ = "products"

    name: str = Field(default="", le=200)
    description: TEXT = Field(default="", sa_type=TEXT)
    product_code: str = Field(default="")

    production_country: str = Field(default="", index=True)
    production_city: str = Field(default="", index=True)

    csr_code: int = Field(default_factory=lambda: randint(100000, 999999))
    csr_image: LONGBLOB = Field(default=None,nullable=False, sa_type=LONGBLOB)

    user_id: int = Field(default=None, foreign_key="users.id")
    user: "User" = Relationship(back_populates="products")




class User(
    BaseEntity,
    table=True
):
    """Class the users"""

    __tablename__ = "users"

    name: str = Field(default="", le=200)
    email: str = Field(default="", le=200, index=True, unique=True)
    password: str = Field(le=500)

    products: list["Product"] = Relationship(back_populates="user")

Description

at the frist query i get this message.
When initializing mapper Mapper[User(users)], expression "relationship("list['Product']")" seems to be using a generic class as the argument to relationship(); please state the generic argument using an annotation, e.g. "products: Mapped[list['Product']] = relationship()"

but only if i add the navigation properties, if i use only the id to create the relation, all works

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.16

Python Version

Python 3.12.2

Additional Context

No response

[ericPavone]

here is the problem.

from future import annotations
from typing import TYPE_CHECKING

if TYPE_CHECKING:
from ... import ...

to keep the type, idk why, all was broken. removing it, all works.

[iamyb]

Hello, what's your final solution here? Seems i met similar issue...

[ericPavone]

The solution is to not use

"from future import annotations
from typing import TYPE_CHECKING

if TYPE_CHECKING:
from ... import ...
"
with the navigation properties defined as Object EG:

products: list[Product] <--- real object type = Relationship(back_populates="user")

use instead: 

products: list["Product"]   <--- string version  = Relationship(back_populates="user")

[kent-foodini]

To help those who find this and puzzle over the discussion:

To sort out massive errors with SQLModel / SQLAlchemy, the "from future import annotations" statement in the file will completely bork SQLAlchemy with errors leading you to think the relationships are based on generic types.

DO NOT USE from future import annotations AND SQL MODEL

I took this line out after hours of trying things, and SQLModel started working again.