Push items into mongo array via mongoose

Question

I ve scoured SO a good bit looking for the answer but I m sure that I m lost for the right words to describe what I m after  Basically I have a mongodb collection called  people  The schema for that collection is as follows  people             name  String            friends    firstName  String  lastName  String              Now  I have a very basic express application that connects to the database and successfully creates  people  with an empty friends array  In a secondary place in the application  a form is in place to add friends  The form takes in firstName and lastName and then POSTs with the name field also for reference to the proper people object  What I m having a hard time doing is creating a new friend object and then  quot pushing quot  it into the friends array  I know that when I do this via the mongo console I use the update function with  push as my second argument after the lookup criteria  but I can t seem to find the appropriate way to get mongoose to do this  db people update  name   quot John quot      push   friends   firstName   quot Harry quot   lastName   quot Potter quot

User · Answer

The  push operator appends a specified value to an array       push     lt field1 gt    lt value1 gt                 push adds the array field with the value as its element    Above answer fulfils all the requirements  but I got it working by doing the following  var objFriends     fname  fname  lname  lname  surname  surname     Friend findOneAndUpdate        id  req body id           push    friends  objFriends         function  error  success            if  error                console log error             else               console log success

User · Answer

In my case  I did this    const eventId   event id    User findByIdAndUpdate id     push    createdEvents  eventId      exec

User · Answer

An easy way to do that is to use the following   var John   people findOne  name   John     John friends push  firstName   Harry   lastName   Potter     John save

User · Answer

Assuming  var friend     firstName   Harry   lastName   Potter      There are two options you have   Update the model in-memory  and save  plain javascript array push    person friends push friend   person save done     or  PersonModel update         id  person  id            push    friends  friend          done      I always try and go for the first option when possible  because it ll respect more of the benefits that mongoose gives you  hooks  validation  etc      However  if you are doing lots of concurrent writes  you will hit race conditions where you ll end up with nasty version errors to stop you from replacing the entire model each time and losing the previous friend you added  So only go to the former when it s absolutely necessary

User · Answer

Another way to push items into array using Mongoose is-  addToSet  if you want only unique items to be pushed into array   push operator simply adds the object to array whether or not the object is already present  while  addToSet does that only if the object is not present in the array so as not to incorporate duplicacy  PersonModel update       id  person  id          addToSet    friends  friend         This will look for the object you are adding to array  If found  does nothing  If not  adds it to the array  References    addToSet MongooseArray prototype addToSet

User · Answer

First I tried this code const peopleSchema   new mongoose Schema     name  String    friends                firstName  String        lastName  String                  const People   mongoose model  quot person quot   peopleSchema   const first   new Note     name   quot Yash Salvi quot     notes                firstName   quot Johnny quot         lastName   quot Johnson quot                   first save    const friendNew       firstName   quot Alice quot     lastName   quot Parker quot      People findOneAndUpdate      name   quot Yash Salvi quot          push    friends  friendNew        function  error  success        if  error          console log error         else         console log success                 But I noticed that only first friend  i e  Johhny Johnson  gets saved and the objective to push array element in existing array of  quot friends quot  doesn t seem to work as when I run the code   in database in only shows  quot First friend quot  and  quot friends quot  array has only one element   So the simple solution is written below const peopleSchema   new mongoose Schema     name  String    friends                firstName  String        lastName  String                  const People   mongoose model  quot person quot   peopleSchema   const first   new Note     name   quot Yash Salvi quot     notes                firstName   quot Johnny quot         lastName   quot Johnson quot                   first save    const friendNew       firstName   quot Alice quot     lastName   quot Parker quot      People findOneAndUpdate      name   quot Yash Salvi quot          push    friends  friendNew          upsert  true       Adding  quot   upsert  true   quot  solved problem in my case and once code is saved and I run it   I see that  quot friends quot  array now has 2 elements   The upsert   true option creates the object if it doesn t exist  default is set to false  if it doesn t work use below snippet People findOneAndUpdate      name   quot Yash Salvi quot          push    friends  friendNew        exec

User · Answer

Use  push to update document and insert new value inside an array   find   db getCollection  noti   find       result for find           id    ObjectId  5bc061f05a4c0511a9252e88         count    1 0       color     green        icon     circle        graph                              date    ISODate  2018-10-24T08 55 13 331Z                 count    2 0                       name     online visitor        read    false       date    ISODate  2018-10-12T08 57 20 853Z           v    0 0     update   db getCollection  noti   findOneAndUpdate        id  ObjectId  5bc061f05a4c0511a9252e88             push                  graph                    date    ISODate  2018-10-24T08 55 13 331Z                    count    3 0                                          result for update           id    ObjectId  5bc061f05a4c0511a9252e88         count    1 0       color     green        icon     circle        graph                              date    ISODate  2018-10-24T08 55 13 331Z                 count    2 0                                    date    ISODate  2018-10-24T08 55 13 331Z                 count    3 0                       name     online visitor        read    false       date    ISODate  2018-10-12T08 57 20 853Z           v    0 0

User · Answer

I ran into this issue as well  My fix was to create a child schema  See below for an example for your models   ---- Person model  const mongoose   require  mongoose    const SingleFriend   require    SingleFriend    const Schema     mongoose Schema   const productSchema   new Schema     friends       SingleFriend schema       module exports   mongoose model  Person   personSchema        Important  SingleFriend schema -  make sure to use lowercase for schema  --- Child schema  const mongoose   require  mongoose    const Schema     mongoose Schema   const SingleFriendSchema   new Schema     Name  String      module exports   mongoose model  SingleFriend   SingleFriendSchema

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