python - FastAPI column products.category_id does not exist

Question

I'm using FastAPI and I am stuck in this error while adding columns to a Model class

Here are my models

class Category(Base):
    __tablename__ = 'categories'

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String, unique=True)
    description = Column(String)

    products = relationship("Product", back_populates="category")


class Product(Base):
    __tablename__ = 'products'
    
    id = Column(Integer, primary_key=True, index=True)
    category_id = Column(Integer, ForeignKey('categories.id'))
    title = Column(String, unique=True)
    price = Column(Float)
    cost = Column(Float)

    category = relationship("Category", back_populates="products")

when the API is running I got this error: sqlalchemy.exc.ProgrammingError: (psycopg2.errors.UndefinedColumn) column products.category_id does not exist

And the problem go on, if I try to add a new attribute to Porduct model there are no changes in my database columns

There is something like run migrations in FastAPI? What I am missing?

question from:https://stackoverflow.com/questions/65929552/fastapi-column-products-category-id-does-not-exist

Answer 1

you will need to use something like Alembic to manage DB migrations. FastAPI does not manage this for you. Here's an example project from FastAPI that shows how to set up Alembic migrations.

https://fastapi.tiangolo.com/tutorial/sql-databases/#alembic-note

https://github.com/tiangolo/full-stack-fastapi-postgresql/tree/master/%7B%7Bcookiecutter.project_slug%7D%7D/backend/app/alembic/