fastApi笔记04-查询参数和字符串校验

额外校验

使用Query可以对查询参数添加校验

from typing import Unionfrom fastapi import FastAPI, Queryapp = FastAPI()@app.get("/items/")
async def read_items(q: Union[str, None] = Query(default=None, max_length=50)):results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}if q:results.update({"q": q})return results

default:默认值

max_length：最大长度

min_length：最小长度

pattern：正则表达式

声明为必须参数

当使用Query声明一个查询参数为必须参数时，只用不声明默认值就行，也就是default不传

from fastapi import FastAPI, Queryapp = FastAPI()@app.get("/items/")
async def read_items(q: str = Query(min_length=3)):results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}if q:results.update({"q": q})return results

使用省略号(...)声明必填参数

from fastapi import FastAPI, Queryapp = FastAPI()@app.get("/items/")
async def read_items(q: str = Query(default=..., min_length=3)):results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}if q:results.update({"q": q})return results

使用Pydantic中的Required代替省略号

from fastapi import FastAPI, Query
from pydantic import Requiredapp = FastAPI()@app.get("/items/")
async def read_items(q: str = Query(default=Required, min_length=3)):results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}if q:results.update({"q": q})return results

使用None声明必须参数

from typing import Unionfrom fastapi import FastAPI, Queryapp = FastAPI()@app.get("/items/")
async def read_items(q: Union[str, None] = Query(default=..., min_length=3)):results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}if q:results.update({"q": q})return results

声明None是个有效类型，这样将强制客户端传一个值。即使这个值是None

查询参数列表，多个值

使用Query显式地定义查询参数时，还可以声明它去接收一组值，或换句话来说，接收多个值。

例如，要声明一个可在 URL 中出现多次的查询参数

from typing import List, Unionfrom fastapi import FastAPI, Queryapp = FastAPI()@app.get("/items/")
async def read_items(q: Union[List[str], None] = Query(default=None)):query_items = {"q": q}return query_items

http://localhost:8000/items/?q=foo&q=bar

要声明类型为List的查询参数，需要显示使用Query，否则该参数将被当做请求体解析

具有默认值的查询参数列表/多个值

from typing import Listfrom fastapi import FastAPI, Queryapp = FastAPI()@app.get("/items/")
async def read_items(q: List[str] = Query(default=["foo", "bar"])):query_items = {"q": q}return query_items

http://localhost:8000/items/

更多元数据

from typing import Unionfrom fastapi import FastAPI, Queryapp = FastAPI()@app.get("/items/")
async def read_items(q: Union[str, None] = Query(default=None,alias="item-query",title="Query string143242542",description="Query string for the items to search in the database that have a good match",min_length=3,max_length=50,pattern="^fixedquery$",deprecated=True,),
):results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}if q:results.update({"q": q})return results