【发布时间】：2022-02-01 21:09:29
【问题描述】：
我对 FASTAPI 比较陌生，但决定使用 Postgres 和 Alembic 建立一个项目。每次我使用自动迁移时，我都设法让迁移创建新版本，但由于某种原因，我没有从我的模型中获得任何更新，因为它们保持空白。我有点不知道出了什么问题。
main.py
from fastapi import FastAPI
import os
app = FastAPI()
@app.get("/")
async def root():
return {"message": os.getenv("SQLALCHEMY_DATABASE_URL")}
@app.get("/hello/{name}")
async def say_hello(name: str):
return {"message": f"Hello {name}"}
数据库.py
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
import os
SQLALCHEMY_DATABASE_URL = os.getenv("SQLALCHEMY_DATABASE_URL")
engine = create_engine("postgresql://postgres:mysuperpassword@localhost/rodney")
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()
def get_db():
db = SessionLocal()
try:
yield db
except:
db.close()
目前为止我唯一的模特
from sqlalchemy import Integer, String
from sqlalchemy.sql.schema import Column
from ..db.database import Base
class CounterParty(Base):
__tablename__ = "Counterparty"
id = Column(Integer, primary_key=True)
Name = Column(String, nullable=False)
env.py (alembic)
from logging.config import fileConfig
from sqlalchemy import engine_from_config
from sqlalchemy import pool
from alembic import context
# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name)
# add your model's MetaData object here
# for 'autogenerate' support
from app.db.database import Base
target_metadata = Base.metadata
# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.
def run_migrations_offline():
"""Run migrations in 'offline' mode.
This configures the context with just a URL
and not an Engine, though an Engine is acceptable
here as well. By skipping the Engine creation
we don't even need a DBAPI to be available.
Calls to context.execute() here emit the given string to the
script output.
"""
url = config.get_main_option("sqlalchemy.url")
context.configure(
url=url,
target_metadata=target_metadata,
literal_binds=True,
dialect_opts={"paramstyle": "named"},
)
with context.begin_transaction():
context.run_migrations()
def run_migrations_online():
"""Run migrations in 'online' mode.
In this scenario we need to create an Engine
and associate a connection with the context.
"""
connectable = engine_from_config(
config.get_section(config.config_ini_section),
prefix="sqlalchemy.",
poolclass=pool.NullPool,
)
with connectable.connect() as connection:
context.configure(
connection=connection, target_metadata=target_metadata
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
现在，当我运行“alembic revision --autogenerate -m “initial setup””时，Alembic 会创建大量迁移
如果有人有任何想法，我会非常感激。干杯！
【问题讨论】：
-
你没有从模型中得到任何输出，对吧？
-
不，不知何故无法识别我的模型。虽然我从 db.database 和 env.py 导入 Base 我设置 target_metadata = Base.metadata
-
是的，对我来说，我也遇到了这个问题。希望我的案例可以帮助您了解您的案例中的问题。我使用 ML 模型通过 FastApi 进行部署。让我解释一下