Mongodb lookup with two ObjectId

Question

I have a little issue getting lookup to work. It returns an empty array. I use contactId field in Billing Collection. And I use the contact _id created when entry in Contact Collection in mongodb (Can see it in Robomongo). I have few Billings with ContactId corresponding to the _id of few Contacts. Is my syntaxe correct ? Do I miss something ? Thank you for your help. Below is my lookup syntaxe

  Contact.aggregate([ { $lookup: { from: "Billing", localField: "_id", foreignField: "contactId", as: "BillingMembership" } } ]).exec(function (err, contacts) { if (err) { return res.status(500).json({ title: 'An error occurred', error: err }); } res.status(200).json({ message: 'Success', obj: contacts }); }); 

Below is the result I get back from the database.

 (4) [Object, Object, Object, Object] 0:Object BillingMembership:Array(0) length:0 __proto__:Array(0) additionalInterests:"MFM/REI" billingEmail:"john@netdr.net" cellPhone:6787025500 dateBirth:"1555-02-02T00:00:00.000Z" firstName:"qtazerqr'efsg" gogsMbrType:"Resident Applicant" gogsYearJoined:"20111" homePhone:6787025500 lastName:"gzaetrsg" memberSuffix:", DO" middleName:"fzerqgrre" notes:"htrfjghdnt" officeEmail:"john@netdr.net" officePhone:6787025500 personalEmail:"john@netdr.net" practiceId:"592e4c1638a494089c50c8c8" praticeType:"MFM/High Risk" spFirstNm:"gsertdhy" spLastNm:"rthytrfgj" spSuffix:"syhtdrh" website:"trshdty" __v:0 _id:"5932db29eb4dfe0de4a8a36d" __proto__:Object 1:Object 2:Object 3:Object 

Mongoose Schema Contact

 var mongoose = require('mongoose'); var Schema = mongoose.Schema; var mongooseUniqueValidator = require('mongoose-unique-validator'); var schema = new Schema({ firstName: {type: String, required: true}, middleName: {type: String, required: true}, lastName: {type: String, required: true}, dateBirth: {type: Date, required: true}, memberSuffix: {type: String, required: true}, officePhone: {type: Number, required: true}, homePhone: {type: Number, required: true}, cellPhone: {type: Number, required: true}, officeEmail: {type: String, required: true}, billingEmail: {type: String, required: true}, personalEmail: {type: String, required: true}, gogsMbrType: {type: String, required: true}, gogsYearJoined: {type: String, required: true}, spFirstNm: {type: String, required: true}, spLastNm: {type: String, required: true}, spSuffix: {type: String, required: true}, notes: {type: String, required: true}, praticeType: {type: String, required: true}, additionalInterests: {type: String, required: true}, website: {type: String, required: true}, practiceId: {type: Schema.Types.ObjectId, ref: 'Practice'} }); schema.plugin(mongooseUniqueValidator); module.exports = mongoose.model('Contact', schema); 

Mongoose Schema Billing

 var mongoose = require('mongoose'); var Schema = mongoose.Schema; var mongooseUniqueValidator = require('mongoose-unique-validator'); var schema = new Schema({ reason: {type: String, required: true}, amount: {type: Number, required: true}, membership: {type: String, required: true}, membershipYear: {type: Schema.Types.ObjectId, ref: 'Membership'}, type: {type: String, required: true}, date: {type: String, required: true}, contactId: {type: Schema.Types.ObjectId, ref: 'Contact'}, conferenceId: {type: Schema.Types.ObjectId, ref: 'Conference'} }); schema.plugin(mongooseUniqueValidator); module.exports = mongoose.model('Billing', schema); 

Answer 1

Solved. thanks to Veeram.

I used Change your from: "Billing" to from: "billings"