Mongoose $lookup object returns empty array - node.js

Question

I have tried other similar kind of questions available but nothing seems to work for me.
I have two collections:
leads:
const mongoose = require("mongoose");
const id = mongoose.Schema.Types.ObjectId;
const leadsSchema = mongoose.Schema(
{
_id: id,
userId: { type: id, ref: "User", required: true },
leadName: String,
leads: [
{
_id: id,
name: String,
status: { type: String, required: false, default: "New" },
leadActivity: { type: String, required: false, default: "No Campaign Set" },
headline: { type: String, required: false },
location: { type: String, required: false },
leadType: { type: id, ref: "LeadsCategory", required: true },
}
],
campaignAssociated: {type: id, ref: "campaign"},
},
{
timestamps: true
}
);
module.exports = mongoose.model("lead", leadsSchema);
leadCategory
const mongoose = require("mongoose");
const leadsCategorySchema = mongoose.Schema(
{
_id: mongoose.Schema.Types.ObjectId,
name: {
type: String,
required: false,
},
leadsData: [{ type: Array, ref: "lead" }],
},
{ timestamps: true }
);
module.exports = mongoose.model("LeadsCategory", leadsCategorySchema);
I am trying to reference/populate the name of the lead from leadscategory schema into the leads
exports.get_single_lead_info = (req, res) => {
const { userId } = req.user;
const { leadid } = req.body;
let idToSearch = mongoose.Types.ObjectId(leadid);
Lead.aggregate([
{
$lookup: {from: 'leadscategories', localField: 'leadType', foreignField: 'name', as: 'type as'}
},
{
$match: {
userId: mongoose.Types.ObjectId(userId),
},
},
{
$unwind: "$leads",
},
{
$match: {
"leads._id": idToSearch,
},
},
])
.exec(function (err, result) {
if (err) {
return res.status(400).json({ message: "Unable to fetch data", err });
}
if (!result.length) {
res.status(404).json("No result found");
} else {
res.status(200).json({ message: "Lead info found", result });
}
});
};
But it outputs me the lookup result as an empty array everytime:
{
"message": "Lead info found",
"result": [
{
"_id": "5ece11cbac50c434dc4b7f2c",
"leadName": "python",
"leads": {
"status": "New",
"leadActivity": "Campaign Set",
"name": "Hailey",
"headline": "Machine Learning | Python",
"location": "New Delhi Area, India",
"_id": "5ece11cbac50c434dc4b7f29",
"leadType": "5ebce0f81947df2fd4eb1060"
},
"userId": "5eba83d37d4f5533581a7d58",
"createdAt": "2020-05-27T07:07:55.231Z",
"updatedAt": "2020-05-27T10:47:42.098Z",
"__v": 0,
"type as": [] //<--- Need lead type name associated inside this
}
]
}
Input: "leadid": "5ece11cbac50c434dc4b7f29"
Any help appreciated.

Answer 1

[
{
$match: {
userId: mongoose.Types.ObjectId(userId),
},
},
{
$unwind: "$leads",
},
{
$match: {
'leads._id': idToSearch,
},
},
{
$lookup: {
from: 'leadscategories',
localField: 'leads.leadType',
foreignField: '_id',
as: 'type as'
}
},
]