Updating fields in array -NodeJs

Question

I have this code that loop through all users in DB then look for specific events based on the id value and if there is a match it should update the field caption with a new given data,

for the code :

1- search all potential user = OK

2 - search and find events based on id = OK

3- update the field caption = NOK

this is my code hope I mentioned everything

router.post('/delete/:id',async (req, res) => {
 const eventId = req.params.id // this is the ID of the event
  User.find({}).lean(true).exec((err, users) => {
    let getTEvent = [];


    for (let i = 0; i < users.length; i++) {
      if (users[i].events && users[i].events.length) {

        for (let j = 0; j < users[i].events.length; j++) {
          if (users[i].events[j]._id === eventId) { 
            console.log('you event is :'+ eventId)  // this statement to verify if really got the correct ID or not
            users[i].events[j].caption ="deleted" // from here the problem
            users[i].save(err => {
              if (err) throw err;
              console.log("status changed saved");
              // Redirect back after the job is done.

            });

          }
        }
      }
    }


  });
  })

the error that I get is that users[i].save is not a function I don't know with what should I replace it,

As per comments @whoami

router.post('/delete/:id', (req, res) =>
  User.findOneAndUpdate({
    "events._id": req.params.id
    },
    { $set: { "events.caption": "yesssss" }
  }, {upsert: true}, (err, user) => {
    if (err) {
      res.send('error updating ');
    } else {
      console.log(user);
      console.log(req.params.id)
  }
}));

Below the mongoDb and event datastructure

Hope I clarified everything ,

Best Regards,

.save() works on mongoose document but not on javaScript object, In your code you've already converted mongoose documents returned from find call to .Js objects using : .lean(true) !! You can use .findOneAndUpdate() with a unique filter to find particular user document & update entire events array. Or more simple instead of reading all docs & iterating in code (Which is not preferred at all) you can take advantage of same .findOneAndUpate() to update docs in just one DB call.. — whoami - fakeFaceTrueSoul
– whoami - fakeFaceTrueSoul, Commented May 21, 2020 at 22:02
Please edit this question with sample docs + input + conditions & required o/p, for a better way to do this.. — whoami - fakeFaceTrueSoul
– whoami - fakeFaceTrueSoul, Commented May 21, 2020 at 22:02
@whoami thank you for your answer do you mean I update this question with what you mention in comments above? — Nodegeek
– Nodegeek, Commented May 21, 2020 at 22:06
I recommend to do so, cause you don't need to do all the things what you're doing right now just to update a field inside an array object..!! — whoami - fakeFaceTrueSoul
– whoami - fakeFaceTrueSoul, Commented May 21, 2020 at 22:07
Yeah I 'm so blind I'm doing it the Hard way i will try to modify and see results — Nodegeek
– Nodegeek, Commented May 21, 2020 at 22:09

whoami - fakeFaceTrueSoul · Accepted Answer · 2020-05-21 23:34:53Z

Actual Issue :

.save() works on mongoose document but not on javaScript object. In your code you've already converted mongoose documents returned from .find() call to .Js objects using : .lean(true).

.lean(true) is used to convert mongoose docs to .Js objects to work manipulate fields inside docs in code.

Fixing code :

const mongoose = require('mongoose');

router.post("/delete/:id", async (req, res) => {
  const eventId = req.params.id; // this is the ID of the event
  await User.find({})
    .lean(true)
    .exec((err, users) => {
      let getTEvent = [];

      for (let i = 0; i < users.length; i++) {
        if (users[i].events && users[i].events.length) {
          for (let j = 0; j < users[i].events.length; j++) {
            if (users[i].events[j]._id === eventId) {
              console.log("you event is :" + eventId);
              users[i].events[j].caption = "deleted";
              users[i]._id = mongoose.Types.ObjectId(users[i]._id); // Converting `_id` string to `ObjectId()` to match with type of `_id` in DB
              let user = new User(users[i]); // Create a mongoose doc out of model
              user.save((err) => { // As we're passing `_id` in doc to `.save()` it will be an update call rather-than insert
                if (err) throw err;
                console.log("status changed saved");
                // Redirect back after the job is done.
              });
            }
          }
        }
      }
    });
});

As I've mentioned this can be done with out this extra process of reading docs/iteration/update call. Using .updateOne() or .updateMany() along with $ positional operator things can be done in one DB call :

 const mongoose = require('mongoose');
router.post("/delete/:id", async (req, res) => {
  const eventId = req.params.id; // this is the ID of the event
  /** We're using `.updateMany` with filter on `events._id` - 
   * So that all user docs which has `'events._id': eventId` will be updated,
   * If you've a particular user needs to be updated used `.updateOne()` with a filter to find that user document - filter kind of `userName` 
   * 
   * Both `.updateMany()` or `.update()` will return write result but not the docs,
   * if you need docs in response use `.findOneAndUpdate` or `.findAndModify()`
   */

   /** `$` helps to update particular object's caption field in `events` array (Object where `{ 'events._id': eventId }` ) */

   await User.updateMany({ 'events._id': eventId },{$set : {'events.$.caption': 'deleted'}}).exec((err)=>{
    if (err) throw err;
    console.log("status changed saved");
    // Redirect back after the job is done.
  })
});

Ref : update-documents

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