How to update a document using update query in mongoose? - node.js

Question

This is the comment key pair I have in my post model:
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const postSchema = new Schema({
user:{
type:Schema.Types.ObjectId,
// required:true,
refPath:'onModel'
},
onModel:{
type:String,
enum:['Doctor','Patient']
},
text:{
type:String,
required:true
},
comments:[{
user:{
type:Schema.Types.ObjectId,
refPath:'onModel'
},
reply:{
type:String
},
date:{
type:Date,
default:Date.now
}
}],
likes:[{
user: {
type: Schema.Types.ObjectId,
ref: 'Patient'
}
}]
})
module.exports= post = mongoose.model('post', postSchema);
When I try pushing object to the likes array by running the following code, it fails. The filter part works fine, just some problem with the update part which ends up executing catch block.
Post.updateOne({ _id: req.params.postid, "likes": { $ne : { user:
authorizedData.jwt_payload.patient._id }}},
{ "$set" : { "likes.$.user": "authorizedData.jwt_payload.patient._id"
}})
.then(re => res.json(re))
.catch(err => res.json("already liked"))
Will really appreciate any help.

Answer 1

Please make changes as below :
const mongoose = require('mongoose');
const patientObjectID = mongoose.Types.ObjectId(authorizedData.jwt_payload.patient._id);
Post.updateOne({
_id: req.params.postid,
'likes.user': {
$ne:
patientObjectID
}
},
{ $push: { likes: { user: patientObjectID } }
}).then(re => res.json(re)).catch(err => res.json("already liked"))
Couple of changes need to be done, So When you've a schema like this ::
likes: [{
user: {
type: Schema.Types.ObjectId,
ref: 'Patient'
}
}]
You need to pass an ObjectId() to user field but not a string, So
first we're converting string to ObjectId() & passing it in query.
Also $set is used to
update existing or insert new fields in a document, but when you wanted to push
new values to an array field in a document then you need to use
$push(this seems to be a normal update operation on a field, but here we're not replacing the likes array, rather we're just adding few more elements to it - different kind of update though, So that's why we need to use $push).
As you already have below filter, we're just doing $push assuming what we're pushing is not a duplicate but in the other way you can blindly use $addToSet to do the same without having to use below filter criteria :
"likes": {
$ne: {
user:
patientObjectID
}
}
About your question on $(update) why it isn't working ? This should be used to update the elements in an array, it helps to update first matching element in an array based on filter criteria, but what you wanted to do here is to add few more elements but not updating existing elements in likes array.
Here you should not send "already liked" in catch block, it should be a custom error for an actual error, in .then(re => res.json(re)) you need to check write result of update operation if anything updated you need to send added user, if not you need to send "already liked".
Hope this solves all your questions :-)

Answer 2

Try using $push aggregation which is used for pushing objects to inner arrays in mongoDB. Your update query should be something like the following:
Post.updateOne({ _id: req.params.postid, "likes": { $ne : { user:
authorizedData.jwt_payload.patient._id }}},
{ "$push" : { "likes": authorizedData.jwt_payload.patient._id
}})
.then(re => res.json(re))
.catch(err => res.json("already liked"))