[英]Select from table defined by SQLAlchemy declarative_base
I am working on FastAPI tutorial and I am trying to create tables using SQLAlchemy+Alembic+ databases .我正在研究 FastAPI 教程,我正在尝试使用 SQLAlchemy+Alembic+ databases创建表。
In my main.py
I have:在我的main.py
,我有:
from typing import List
import databases
import sqlalchemy
from fastapi import FastAPI
from pydantic import BaseModel
from sqlalchemy import Table
DATABASE_URL = "sqlite:///./test.db"
database = databases.Database(DATABASE_URL)
metadata = sqlalchemy.MetaData()
notes = sqlalchemy.Table(
"note",
metadata,
sqlalchemy.Column("id", sqlalchemy.Integer, primary_key=True),
sqlalchemy.Column("text", sqlalchemy.String),
sqlalchemy.Column("completed", sqlalchemy.Boolean),
)
class Note2(BaseModel):
id: int
text: str
completed: bool
app = FastAPI()
@app.on_event("startup")
async def startup():
await database.connect()
@app.on_event("shutdown")
async def shutdown():
await database.disconnect()
@app.get("/notes/", response_model=List[Note2])
async def read_notes():
query = notes.select()
return await database.fetch_all(query)
And this works - I can GET
/notes/ endpoint.这有效 - 我可以GET
/notes/端点。 But it looks newbie to create a datatabase table in the same module with endpoints, so I decided to make models.py
file and create a normal model there, like this:但是在具有端点的同一模块中创建数据库表看起来很新手,所以我决定制作models.py
文件并在那里创建一个普通的 model ,如下所示:
import sqlalchemy as sa
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class Note(Base):
__tablename__ = "note"
id = sa.Column(sa.Integer, primary_key=True)
text = sa.Column(sa.String)
completed = sa.Column(sa.Boolean)
And here comes a problem - when I change the endpoint like this:这里出现了一个问题 - 当我像这样更改端点时:
from app_second.models import Note
@app.get("/notes/", response_model=List[Note2])
async def read_notes():
query = Note().select()
return await database.fetch_all(query)
I recieve an error:我收到一个错误:
AttributeError: 'Note' object has no attribute 'select' AttributeError: 'Note' object 没有属性 'select'
As it is mentioned here - declarative_base()
is just a syntactic shugar for Table
+ mapper
.正如这里提到的 - declarative_base()
只是Table
+ mapper
的语法 shugar 。 But what is the right way to select/filter/update tables declared that way?但是以这种方式声明的选择/过滤/更新表的正确方法是什么?
You can use the table property to access the table methods and then use database.fetch_all() or similar.您可以使用table属性来访问 table 方法,然后使用 database.fetch_all() 或类似的。 Eg:例如:
from sqlalchemy import select
...
skip = 0
limit = 100
query = (
Note.__table__.select()
.offset(skip)
.limit(limit)
)
return await database.fetch_all(query)
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