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

python 复制代码

from typing import Union

from fastapi import FastAPI, Query

app = 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

python 复制代码

from fastapi import FastAPI, Query

app = 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

python 复制代码

from fastapi import FastAPI, Query

app = 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

python 复制代码

from fastapi import FastAPI, Query
from pydantic import Required

app = 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

python 复制代码

from typing import Union

from fastapi import FastAPI, Query

app = 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

python 复制代码

from typing import List, Union

from fastapi import FastAPI, Query

app = 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

python 复制代码

from typing import List

from fastapi import FastAPI, Query

app = 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

python 复制代码

from typing import Union

from fastapi import FastAPI, Query

app = 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

alias：参数别名
title：不知道啥效果，没试出来
description：自动文档上的参数描述
deprecated：True时自动文档提示弃用参数