python - 使用 Flask 验证参数

Question

我对 Flask 完全是个菜鸟，当我开始学习它时，我遇到了一些麻烦。具体来说，我想验证某些参数的存在性和类型。

做了一些研究，我发现了来自flask-restful的RequestParser类。

所以，这就是我的方法:

@app.route("/", methods=['POST'])
def testing():

    if request.method == 'POST':
        try:
            parser = reqparse.RequestParser(bundle_errors=True)
            parser.add_argument('x1', type=float, help="x1 must be float")
            parser.add_argument('x2', type=float, help="x2 must be float")
            parser.add_argument('x3', choices=(1,2), help="x3 must be binary")

            return jsonify({'test': 'ok})
        except:
            pass

如果输入正常，这对我的测试代码非常有用:

data = {
   "x1" : 100,
   "x2" : 200,
   "x3" : 300
}

BASE_URL = "http://localhost:5000"
response = requests.post("{}/predict".format(BASE_URL), json = data)
response.json()

# {'x1': 100.0, 'x2': 200.0, 'x3': 300}

但是，使用:

data = {
    "x1" : "a",
    "x2" : 200,
    "x3" : 300
}

我开始面对JSONDecodeError。使用 print(resnpose) 我看到 API 返回代码 400，但没有任何错误。如何以字典的形式返回错误？例如:

{"x1" : "x1 should be float"}

错误回溯:

Traceback (most recent call last):
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\app.py", line 1997, in __call__
    return self.wsgi_app(environ, start_response)
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\app.py", line 1985, in wsgi_app
    response = self.handle_exception(e)
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\app.py", line 1540, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\_compat.py", line 33, in reraise
    raise value
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\app.py", line 1615, in full_dispatch_request
    return self.finalize_request(rv)
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\app.py", line 1630, in finalize_request
    response = self.make_response(rv)
  File "C:\Users\me\AppData\Local\Continuum\Anaconda3\lib\site-packages\flask\app.py", line 1725, in make_response
    raise ValueError('View function did not return a response')
ValueError: View function did not return a response

谢谢。

Answer 1

对于第一次误读问题表示歉意。

因此，根据http://flask-restful.readthedocs.io/en/0.3.5/reqparse.html#error-handling，您几乎可以用这种方式处理它

parser = reqparse.RequestParser()
parser.add_argument(‘foo’, choices=(‘one’, ‘two’), help=’Bad choice: {error_msg}’)

那么，

{
"message": { "foo": "Bad choice: three is not a valid choice", }
}