FastAPI返回字典

Question

我正试着用FastAPI归还一本字典。我搜索了他们的网站，却找不到任何有用的东西。也许我说的是完全错误的，但我可以想象我可以给它一个结果字典，它会返回它们作为结构在字典中？最终的目标是将这些信息从数据库中提取出来，但是为了简单和测试，我已经把它缩小到了这个范围。

from typing import List, Optional
   
from fastapi import FastAPI
from pydantic import BaseModel
    
app = FastAPI()
    
class Item(BaseModel):
    name: str
    description: Optional[str] = None
    price: float
    tax: float = 10.5
    tags: List[str] = []
    
class Items(BaseModel):
    items: List[Item]
    
itemslist = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},
    "baz": {"name": "Baz", "description": None, "price": 50.2, "tax": 10.5, "tags": []},
}
   
@app.get("/items", response_model=Items, response_model_exclude_unset=True)
async def read_item(Items: dict):
    return Items(items=itemslist)

当我打开页面时

{
"detail": [
  {
    "loc": [
      "body"
    ],
    "msg": "field required",
    "type": "value_error.missing"
    }
  ]
}

在控制台日志中我看到

127.0.0.1:53845 - "GET /items HTTP/1.1" 422 Unprocessable Entity

Answer 1

您的代码有几个问题：

1. 当您在get端点的函数定义中指定一个参数时，该参数将被期望在正文中发送。这就是为什么错误消息在body字段中显示loc .

的原因。

@app.get("/items", response_model=Items, response_model_exclude_unset=True)
async def read_item():
    return Items(items=itemslist)

1. --您已经将itemslist定义为dict，但希望将其转换为list。另外，通常情况下，数据库适配器将返回行或类似的list。这就是为什么我会把它改为这样的东西：

itemslist = [
    {"name": "Foo", "price": 50.2},
    {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},
    {"name": "Baz", "description": None, "price": 50.2, "tax": 10.5, "tags": []},
]

这可能会做到这一点，调用端点应该返回：

$ curl http://127.0.0.1:8000/items | jq
{
  "items": [
    {
      "name": "Foo",
      "price": 50.2
    },
    {
      "name": "Bar",
      "description": "The bartenders",
      "price": 62,
      "tax": 20.2
    },
    {
      "name": "Baz",
      "description": null,
      "price": 50.2,
      "tax": 10.5,
      "tags": []
    }
  ]
}

评论

如果Items只包含一个list of Item，我建议保持简单，然后返回List[Item] (使用pydantic的parse_obj_as)：

from pydantic import parse_obj_as

# ...

@app.get("/items", response_model=List[Item], response_model_exclude_unset=True)
async def read_item():
    return parse_obj_as(List[Item], itemslist)

但是，请注意，在这种情况下，输出略有不同：

$ curl http://127.0.0.1:8000/items | jq
[
  {
    "name": "Foo",
    "price": 50.2
  },
  {
    "name": "Bar",
    "description": "The bartenders",
    "price": 62,
    "tax": 20.2
  },
  {
    "name": "Baz",
    "description": null,
    "price": 50.2,
    "tax": 10.5,
    "tags": []
  }
]