how to terminate rest request gracefully - python-3.x

Question

I want to terminate rest request coming to server without further processing if input params are missing.
Currently this is the implementation, which I think is not very good for verify_required_params().
I want to terminate this request without returning any value from verify_required_params() in case of missing params. else flow should continue.
Running this on flask server and open to include any new package for best/ optimized approach.
Can please someone suggest an optimize way for this?
#app.route('/is_registered', methods=['POST'])
def is_registered():
_json = request.get_json()
keys = _json.keys()
customer = Customer()
if verify_required_params(['mobile'], keys) is True:
_mobile = _json['mobile']
validated = validate_mobile(_mobile)
registered = customer.find(_mobile)
if not validated:
response = get_response('MOBILE_NUMBER_NOT_VALID')
return jsonify(response)
if not registered:
response = get_response('MOBILE_NUMBER_NOT_REGISTERED')
return jsonify(response)
response = get_response('MOBILE_NUMBER_REGISTERED')
return jsonify(response)
else:
return verify_required_params(['mobile'], keys)
def verify_required_params(required, received):
required = set(required)
received = set(received)
missing = list(sorted(required - received))
data = {"missing_key(s)": missing}
# response = app.response_class(
# response=json.dumps(data),
# status=200,
# mimetype='application/json'
# )
if missing:
return jsonify(data)
return True

Answer 1

🎶 You say it works in a RESTful way, then your errors come back as 200 OK 🎶
In REST, your URL should encode all the information about your entity. In your case, you are identifying a client by their phone number, and you are getting rather than updating information about them, so your endpoint should look like GET /client/<phonenumber>/registered. That way, a request can't not provide this information without going to a different endpoint.
In short, your code will be replaced with:
#app.route('/client/<mobile>/registered', methods=['GET'])
def is_registered(mobile):
if not mobile.is_decimal():
return jsonify({'error': 'mobile is not number'}), 400 # Bad Request
customer = Customer()
registered = bool(customer.find(mobile))
# does it make sense to have a customer who is not registered yet?
# if not, use:
if not registered:
return jsonify({'error': 'client not found'}), 404 # Not Found
validated = validate_mobile(mobile)
return jsonify( {'validated': validated, 'registered': registered} )
In addition, it's better to have the validation function be a decorator. That way it gets called before the actual business logic of the function. For your example of checking whether request.get_json() contains the proper fields, this is how it would look like:
import functools
def requires_fields(fields):
required_fields = set(fields)
def wrapper(func):
#functools.wraps(decorated)
def decorated(*args, **kwargs):
current_fields = set(request.get_json().keys())
missing_fields = required_fields
if missing_fields:
return jsonify({'error': 'missing fields', 'fields': list(missing_fields)}), 400 # Bad Request
resp = func(*args, **kwargs)
return resp
return wrapper
# usage:
#app.route('/comment', methods=['POST'])
#requires_fields(['author', 'post_id', 'body'])
def create_comment():
data = request.get_json()
id = FoobarDB.insert('comment', author=data['author'], post_id=data['post_id'], body=data['body'])
return jsonify({'new_id': id}), 201 # Created
If you must leave it the way it is now, then in order to not return data from the validation function, you must raise an HTTPException. The default function to do it is flask.abort(code).