How do you update a nested array with Mongoose? - mongodb

Question

This is what I have so far. This is my AnswerSchema with a comments array nested within that I am trying to update.
const AnswerSchema = new Schema({
user: {
type: Schema.Types.ObjectId,
ref: 'user',
},
question: {
type: Schema.Types.ObjectId,
ref: 'question',
},
text: {
type: String,
required: true,
},
name: {
type: String,
},
avatar: {
type: String,
},
views: {
type: Number,
},
date: {
type: Date,
default: Date.now,
},
answerLikes: [
{
user: {
type: Schema.Types.ObjectId,
ref: 'user',
},
},
],
comments: [
{
user: {
type: Schema.Types.ObjectId,
ref: 'user',
},
text: {
type: String,
required: true,
},
name: {
type: String,
},
avatar: {
type: String,
},
commentLikes: [
{
user: {
type: Schema.Types.ObjectId,
ref: 'user',
},
},
],
date: {
type: Date,
default: Date.now,
},
},
],
})
and here is my update route that I am trying to use to update the comments array text field
try {
const updatedAnswer = await Answer.findOneAndUpdate(
{ _id: req.params.answer_id },
{
$set: { 'comments.$[comment].text': formattedAnswer },
},
{
arrayFilters: [{'comment._id': req.params.comment_id }],
},
{ new: true }
)
res.json(updatedAnswer)
I keep getting the error 'Callback must be a function, got [object Object]' and cant figure out a fix.
Any ideas?
Thanks!

Answer 1

The problem in your code is that you are passing 4 parameters to the findOneAndUpdate function.
The 4th argument is a callback which accepts a function:
(err /* an error if occurred */, doc /* the updated document */) => {}
In order to solve that you need to combine your last 2 arguments into one object like:
{
arrayFilters: [{'comment._id': req.params.comment_id }],
new: true
}
Final query:
const updatedAnswer = await Answer.findOneAndUpdate(
{ _id: req.params.answer_id },
{
$set: { 'comments.$[comment].text': formattedAnswer },
},
{
arrayFilters: [{'comment._id': req.params.comment_id }],
new: true
}
)

Answer 2

The 4th argument in findOneAndUpdate function takes in a callback function that was where your error was.
Try this
try{
const updatedAnswer = await Answer.findOneAndUpdate(
{ _id: req.params.answer_id },
{
$set: { 'comments.$[comment].text': formattedAnswer },
},
{
arrayFilters: [{'comment._id': req.params.comment_id }],
new: true
}
);
res.json(updatedAnswer);
}catch(err){
//console.log(err)
}