flask.py

import json
from functools import wraps

from flask import request

from utils.exceptions import HttpNotFound
from utils.validators import Required

def require(f):
    @wraps(f)
    def decorated(view):
        if request.method not in ['POST', 'PUT'] or not request.data:
            return f(view)

        required_payload = []

        for key in view.model.__dict__:
            if key.startswith('validate_'):
                validators = view.model.__dict__[key].validators

                if any([isinstance(validator, Required)
                        for validator in validators]):
                    required_payload.append(key[9:])
                    
        data = json.loads(request.data)        
        
        fields = set(required_payload) - set(data.keys())
        if fields != set([]):
           raise HttpNotFound({
               'error': 'Field %s was not found in payload' % "".join(fields)
           })

        request.data = json.dumps({
            column: data[column] for column in view.model.columns
        })

        return f(view)

    return decorated