SQL Alchemy - Base.metadata.create_all(bind=engine) 不在测试数据库中创建表

Question

I am using FastAPI to build an API backend for my URL shortener. I have the database connected to the API as a dependency. For the CRUD operations, I am using the SQL Alchemy ORM.

The code for my main app works perfectly fine and performs all the major CRUD operations I have mapped through the API endpoints.

The problem arises when I try to override the DB dependency to use a test db instead of my production db for testing purposes.

There are no errors associated with this override, however, the test database does not contain any of the tables that would be created when Base.metadata.creat_all(bind=engine) is called.

When running the tests using pytest , it gives me this error:

sqlalchemy.exc.ProgrammingError: (pymysql.err.ProgrammingError) (1146, "Table 'testurldb.urls' doesn't exist")

The code for my tests:

engine = create_engine(
    "mysql+pymysql://{user}:{password}@{ip}:{port}/testurldb".format(
        user=user, password=password, ip=ip, port=port
    )
)
Session = sessionmaker(bind=engine)
Base.metadata.create_all(bind=engine)


def overrideDB():
    db = Session()
    try:
        yield db
    finally:
        db.close()


app.dependency_overrides[get_db] = overrideDB

client = TestClient(app)

The module where Base is instantiated:

engine = create_engine(
    "mysql+pymysql://{root}:{password}@{ip}:{port}/urldb".format(
        root=root, password=password, ip=ip, port=port
    )
)

SessionLocal = sessionmaker(bind=engine)
Base = declarative_base()

The table that extends Base:

class URL(Base):
    __tablename__ = "urls"

    short_url = Column(String(256), primary_key=True, unique=True, nullable=False)
    long_url = Column(String(256), nullable=False, unique=True)
    time = Column(String(256), nullable=False)

    def __init__(self, short_url, long_url, time):
        self.short_url = short_url
        self.long_url = long_url
        self.time = time

There seems to be nothing wrong with the imports, so I don't understand why it's not creating the tables.

And second, it might be useful information that my main production db already has the Tables created.

Answer 1

Create a file and import all models into it, at the end of all imports, put the Model import. When doing this, try to create the models again through Base.metadata

Answer 2

i hope it'll helps you

db.py

Base = declarative_base()


async def init_db():
    try:

        Base.metadata.create_all(bind=engine)
    except Exception as e:
        raise e

main.py

@app.on_event("startup")
async def on_startup():
    await init_db()