Alembic Can't Detect my Models

[Valent-p]

Describe the bug
I am using alembic with fastapi. In my project, I have 3 initial DB models: User, Item and OtherItem.

I tried everything, but alembic can't detect any of the models. I tried debugging, rewriting and everything i could find online including official docs. But no fix. After 5 straight hours of frustrations, just before I giving up, I tried to replace Base.metadata with User.metadata after importing the models into env.py, then bingooo, it works. But this seems not right because I couldn't find any explanation like that. Even when i told someone, he said I have to use Base not User. So, I think this is a bug, because my head hurts due to this hours of mental pain.

Expected behavior
According to docs, I expected Base.metadata to work without any issue. And my models to be detected automatically.

[zzzeek]

, I tried to replace Base.metadata with User.metadata after importing the models into env.py, then bingooo, it works.

this means that User.metadata and Base.metadata are not the same MetaData object. you likely are using a pattern like this:

class Base(DeclarativeBase):
    pass


class User(Base):
    __tablename__ = "user"

    metadata = MetaData()

that's a valid pattern though is not too common since there's usually not much reason for it, unless you have your models broken out into several MetaData collections, in which case yes you need to indicate the correct one in your env.py that you want to derive migrations from.

[Valent-p]

No, I didn't do like that.

It's like:

class Base(DeclarativeBase):
  pass

class User(Base):
  __tablename__ = "users"
  id: Mapped[int] = mapped_column(Integer, primary_key=True)
  name: Mapped[str] = mapped_column(String(32))

Just like that

[CaselIT]

is your user defined in the same file as the base? how is your env.py?