Use WTForms for RESTful Api Validation on Google Cloud Functions (Python)

# https://pypi.org/project/WTForms/
WTForms==2.2.1

from wtforms import Form, BooleanField, StringField, validatorsclass RequestInviteForm(Form):    email = StringField('Email', [validators.Length(min=6, max=120), validators.Email()])    # email = StringField('Email', [validators.Email()])

from flask import jsonify, abort# https://cloud.google.com/apis/design/errors#http_mappingdef json_abort(status_code, message, details=None):    data = {        'error': {            'code': status_code,            'message': message        }    }    if details:        data['error']['details'] = details    response = jsonify(data)    response.status_code = status_code    abort(response)

from flask import jsonifyfrom werkzeug.datastructures import ImmutableMultiDictdef request_invite(request):    '''    data = request.json.get('data')    if 'email' not in data:        json_abort(400, message="Missing email")    '''    if not request.is_json:        json_abort(400, 'JSON request expected')    form = RequestInviteForm(ImmutableMultiDict(request.json.get('data')))    if not form.validate():        json_abort(400, 'validation error', details=form.errors)    email = form.email.data    # so something    return jsonify({        'data': {            'email': email        }    })