How to iterate on mongoose subdocument array of objects - mongodb

Question

Trying to implement conditional statement relying on subdocument array of objects, so i need to iterate over collection of users in database and check inside each user subdocument array of objects with findIndex as for javascript
Users collection
const mongoose = require("mongoose");
const userSchema = new mongoose.Schema({
username: {
type: String,
unique: true,
required: true,
lowercase: true
}
friends: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "User"
}
],
family: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "User"
}
],
acquaintances: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "User"
}
],
following: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "User"
}
],
pendingFriendConfirmationData:[
{
storedUserId : {type: String},
choosenCategories: [{label: {type: String}, value: {type: String}}]
}
]
});
const Users = mongoose.model("Users", userSchema);
module.exports = Users;
now i can access Users collection with
db.Users.find()
my example result for
let filter = {"_id": userId}
let projection = {username: 1, friends: 1, family: 1, acquaintances: 1, following: 1, pendingFriendConfirmationData: 1}
db.Users.findOne(filter, projection, (err, user)=>{
console.log(user)
})
{
friends: [],
family: [],
acquaintances: [],
following: [],
_id: 5ca1a43ac5298f8139b1528c,
username: 'ahmedyounes',
pendingFriendConfirmationData: [
{
choosenCategories: [Array],
_id: 5ccb0fcf81a7944faf819883,
storedUserId: '5cc95d674384e302c9b446e8'
}
]
}
focusing on pendingFriendConfirmationData
the following screenshot from MongoDB Compass
I want to iterate over like this
let filter = {"_id": userId}
let projection = {username: 1, friends: 1, family: 1, acquaintances: 1, following: 1, pendingFriendConfirmationData: 1}
db.Users.findOne(filter, projection, (err, user)=>{
let data = user.pendingFriendConfirmationData
for(let i in data){
if(data[i].choosenCategories.findIndex(v => v.label === "friend") !== -1){
console.log("he is a friend")
}
}
})
How to iterate over pendingFriendConfirmationData and choosenCategories
like above
for now if i console.log(data) as following
db.Users.findOne(filter, projection, (err, user)=>{
let data = user.pendingFriendConfirmationData
console.log(data)
})
I get

Answer 1

I figured it out Faster Mongoose Queries With Lean
The lean option tells Mongoose to skip hydrating the result documents. This makes queries faster and less memory intensive, but the result documents are plain JavaScript objects (POJOs), not Mongoose documents. In this tutorial, you'll learn more about the tradeoffs of using lean().
In my previous example the solution would be adding {lean: true}
db.Users.findOne(filter, projection, {lean: true}, (err, user)=>{
let data = user.pendingFriendConfirmationData
console.log(data)
})
also here
db.Users.findOne(filter, projection, {lean: true}, (err, user)=>{
let data = user.pendingFriendConfirmationData
for(let i in data){
if(data[i].choosenCategories.findIndex(v => v.value === "friends") !== -1){
console.log("he is a friend")
}
}
})
// he is a friend
Conclusion
to iterate over deeply nested subdocument array of objects you need to make sure
that you are working with plain JavaScript objects (POJOs) using lean()
db.Users.find().lean()