FastAPI

Question

我有 2 个 api 端点。这个 return 是我所有用户的列表。

@app.get("/entity/", response_model=List[schemas.Userentity])
def read_entities(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
    users = crud.get_entities(db, skip=skip, limit=limit)
    return users

def get_entities(db: Session, skip: int = 0, limit: int = 100):
    return db.query(models.Userentity).offset(skip).limit(limit).all()

这很好用。查看数据：

[
{
"id": "89f8a844-a30e-41b2-947d-6eb0fcadb1bf",
"email": "xxx@hotmail.com",
"first_name": "xxx",
"last_name": "xxx",
"username": "schoedeld",
"created_timestamp": "1633711745164"
},
{
"id": "abd6bb6b-ad80-431c-9f64-d9e651638f4c",
"email": "xxxsd@hotmail.com",
"first_name": "xxx",
"last_name": "xxx",
"username": "xxx",
"created_timestamp": "1633711733338"
},
{
"id": "ad0bd5ca-5aed-4d7f-a6ac-2620f2133685",
"email": "xxxx@hotmail.com",
"first_name": "fsdfs",
"last_name": "fsdfs",
"username": "testadmin",
"created_timestamp": "1633710812666"
}
]

这里我有一个指向 return 单个用户的端点：

我可以 return 一个包含单个元素的列表，但我想 return 一个值，所以我将端点更新为：

@app.get("/entity/{id}", response_model=schemas.Userentity)
def read_entity(id: str, db: Session = Depends(get_db)):
    user = crud.get_entity(db, id=id)
    return user

def get_entity(db: Session, id: str):
    return db.query(models.Userentity).filter_by(id=id)

这会导致以下错误：

pydantic.error_wrappers.ValidationError: 6 validation errors for Userentity
response -> id
  field required (type=value_error.missing)
response -> email
  field required (type=value_error.missing)
response -> first_name
  field required (type=value_error.missing)
response -> last_name
  field required (type=value_error.missing)
response -> username
  field required (type=value_error.missing)
response -> created_timestamp
  field required (type=value_error.missing)

我是 FastAPI 的新手，不明白为什么会出现这个错误，谁能帮我解释一下我做错了什么？

Answer 1

您实际上从未运行查询您的 SQLAlchemy 查询，所以您 return查询本身：

return db.query(models.Userentity).filter_by(id=id)

相反，您应该通过以下任一方式使 SQLAlchemy 运行成为您的查询：

# raise an exception if not exactly one row is returned (so more than one or zero)
return db.query(models.Userentity).filter_by(id=id).one()

# Either one or zero rows - return `None` if user wasn't found
return db.query(models.Userentity).filter_by(id=id).one_or_none()

# Return None if user isn't found, otherwise return the first row
# (multiple rows isn't an error)
return db.query(models.Userentity).filter_by(id=id).first()

下次在您的视图函数的 return 调用处附加设置调试器断点（或至少 print 值），您可以准确地看到您要 return 到 FastAPI 进行序列化。

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