FastAPI系列：查询字符串参数额外校验Query

设置默认值

@app.get("/items/")
async def read_items(q: Union[str, None] = Query(default=None, max_length=50)): # Query适用于查询参数中，设置默认值为None，并且规定最大长度为50
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})
    return results

不设置默认值，必填查询字符串

@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

不设置默认值，必填查询字符串的另一种写法（...）省略号

@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

不设置默认值，必填查询字符串的另一种写法Required

from pydantic import Required

@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