Mongodb join query from nodejs - node.js

Question

I am new to MongoDB and trying to join two query and store result in a single model. I want to fetch client name from another collection while fetching client task.
Model:-
const mongoose = require('mongoose');
var ObjectId = mongoose.Schema.Types.ObjectId;
const ClientTaskSchema = new mongoose.Schema({
clientId: {
type: Number
},
taskId: {
type: Number
},
clientTaskId: {
type: Number
},
active: {
type: Boolean
}
});
module.exports = mongoose.model('ClientTask', ClientTaskSchema);
Controller:-
module.exports.getClientByTask = function(req, res) {
var query = url.parse(req.url,true).query;
ClientTask.find({taskId: query.taskId}, function(err, clientTask) {
if (err) throw err;
if (!clientTask) {
res.status(200).json({ success: false, message: 'Somthing went wrong. Please contact admin.'});
}
else {
res.status(200).json({ success: true, message: 'Successfull', data: clientTask});
}
});
};

Answer 1

One option is to pass clientId as a reference:
clientId: {
type: mongoose.Schema.Types.ObjectId, ref: 'Client / or whatever your model'
}
Then you'll be able to use Mongoose's populate method http://mongoosejs.com/docs/populate.html
ClientTask
.find({ taskId: query.taskId })
.populate('clientId', { name: 1 }).exec(function (err, clientTask) {
if (!clientTask) {
res.status(404).json({ message: 'Client task not found' })
}
// your logic
});

Answer 2

You can fetch aggregated data with mongodb aggregate. To Calculates aggregate values for the data in a collection:
$lookup Performs a left outer join to an unsharded collection in the same database to filter in documents from the “joined” collection for processing. To each input document, the $lookup stage adds a new array field whose elements are the matching documents from the “joined” collection. The $lookup stage passes these reshaped documents to the next stage.
In your case:
Model.ClientTask.aggregate([
{
$lookup:
{
from: "client",
localField: "_id",
foreignField: "clientId",
as: "clientData"
},
},
{
$project: {
"name": clientData.name, // This name will be client name from client collections
"taskId": 1,
"clientTaskId": 1,
"active": 1
}
}
],
function (err, response) {
console.log(err, response)
});