javascript - How to push returned value into an array mongodb? -

i getting correct data friendrequests getting user id , throwing in friendrequest field of mongoose file. when add $push add data friendrequest array in route file, not insert , gives me err function created.

here route file:

exports.addcontactpost = function(req, res, err) {     user.findbyidandupdate(req.signedcookies.userid, {                 $push: {friendrequest: req.body.friendrequest}             }, function(err) {                 if(err) {                     console.log("post2");                     return console.log('error');                  }                   else {                     console.log('postsuccess');                     res.json({response: true});                  }              }); }; 

here mongoose file:

var mongoose = require('mongoose'),     schema = mongoose.schema,     bcrypt = require('bcrypt-nodejs'),     salt_work_factor = 10;   var userschema = new schema({      email: { type: string, required: true, lowercase:true, index: { unique: true } },     password: { type: string, required: true },     firstname: {type: string, required: true},     lastname: {type: string, required: true},     phone: {type: number, required: true},     birthday: {type: date, required: true},     friendrequest: {type: array},     friend: {type: array} });   userschema.pre('save', function(next) {     var user = this;     console.log("email exists");     // hash password if has been modified (or new)     if (!user.ismodified('password')) return next();     // generate salt     bcrypt.gensalt(salt_work_factor, function(err, salt) {         if (err) return next(err);         // hash password along our new salt         bcrypt.hash(user.password, salt, null, function(err, hash) {             if (err) return next(err);             // override cleartext password hashed 1             user.password = hash;             next();         });     });     });  userschema.methods.comparepassword = function(candidatepassword, cb) {     bcrypt.compare(candidatepassword, this.password, function(err, ismatch) {         if (err) return cb(err);         cb(null, ismatch);     }); };   module.exports = mongoose.model('user', userschema); 

so document mongo finds matching provided userid not have array friendrequest property. @ specific document id in mongo shell , fix friendrequest array.