methods.signup = async (req,res,next) => {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
        return res.status(config.errorCodes.validation).json({errors:errors.array()});
    }
    let payload = req.body;
    var newUser = new User({
        username:payload.username,
        fullname:payload.fullname,
        email: payload.email,
        password: payload.password,
        urltoken:{
            token:null
        },
        actStatus: 0,
        provider: 'email',
       role:1
    });
    let hash = commonMethods.generatePasswordHash(payload.password);
    let token = commonMethods.createRandomString();

    let [a,b] = await Promise.all([hash,token]).catch(err=>{
        res.status(400).json({status:false,msg:"error in promise"})
     });

    newUser.password = a;
    newUser.urltoken.token = b;
    newUser.save(function(err){
        if(err) {
            return res.status(config.errorCodes.success).json({ status:false
        ,msg:"Error in saving userdata. Please try again",err});
        }
        else {
            commonMethods.sendMail(newUser);
            return res.status(config.errorCodes.success).json({"status":true,
        "msg":"Registered succesfully. Please Check your Email to verify
        your account.",newUser})
    }
});
}

commonMethods.createRandomString = function(password){
    return new Promise(function(resolve, reject) {
    var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
    var string_length = 25;
    var randomstring = '';
    for (var i=0; i<string_length; i++) {
        var rnum = Math.floor(Math.random() * chars.length);
        randomstring += chars.substring(rnum,rnum+1);
    }
   reject(randomstring);
   // resolve(randomstring);

})
}

UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:15172) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.