FastAPI: 请求查询参数的校验（4）

可以通过Query来实现对字符串查询参数的校验。

常规校验

books = [{'name': 'python'}, {'name': 'fastapi'}, {'name': 'java'}]

@app.get('/books/')
def root(book: str = Query('Java Script', min_length=2)):

    if book:
        books.append({'name': book})
    return books

参数的默认值是Java Script，最小长度是2。

http://127.0.0.1:8000/books/
[{"name":"python"},{"name":"fastapi"},{"name":"java"},{"name":"Java Script"}]

http://127.0.0.1:8000/books/?book=c
{"detail":[{"loc":["query","book"],"msg":"ensure this value has at least 2 characters","type":"value_error.any_str.min_length","ctx":{"limit_value":2}}]}

甚至可以直接用正则表达式来做检验，一般应该也用不到。

@app.get('/books/')
def root(book: Optional[str] = Query('Java Script', min_length=2, regex='^J')):

    if book:
        books.append({'name': book})
    return books

必填参数

可以将 ... 用作第一个参数值，在声明必填参数。

@app.get('/books/')
def root(book: str = Query(..., min_length=2, regex='^J')):

    if book:
        books.append({'name': book})
    return books

参数列表多个值

查询参数可以声明时接受多个值

books = ['python', 'fastapi']

@app.get('/books/')
def root(book: Optional[list] = Query(None)):

    if book:
        books.extend(book)
    return books

结果

http://127.0.0.1:8000/books/
["python","fastapi"]

http://127.0.0.1:8000/books/?book=java&book=c
["python","fastapi","java","c"]

还有下面的校验，用到再说

• alia
• title
• description
• deprecated