How to query to get all documents referenced to another collection based on one field as username - mongodb

Question

In my Node API and MongoDB, I'm trying to make an endpoint to get all the posts associated with one username of a profile. In my Profile schema, I have a reference to the Post Schema and in my Post schema, I have a reference to the Username from Profile schema.
My issue I don't know how to get all the posts for that username. I did similarly but with embedded for the Experience schema but I'm not sure how to do that for the referenced collections.
Post model:
const { Connect } = require("../db");
const reactionSchema = {
likedBy: {
type: String,
unique: true,
sparse: true
}
};
const postSchema = {
text: {
type: String,
required: true,
unique: true,
sparse: false
},
username: {
type: Connect.Schema.Types.String,
ref: "Profile"
},
image: {
type: String,
default: "https://via.placeholder.com/150",
required: false
},
createdAt: {
type: Date,
default: Date.now,
required: false
},
updatedAt: {
type: Date,
default: Date.now,
required: false
},
reactions: [reactionSchema],
comments: {
type: Connect.Schema.Types.ObjectId,
ref: "Comment",
required: false
}
};
const collectionName = "post";
const postSchemaModel = Connect.Schema(postSchema);
const Post = Connect.model(collectionName, postSchemaModel);
module.exports = Post;
Profile model:
// Here defining profile model
// Embedded we have the Experience as []
const { Connect } = require("../db");
const { isEmail } = require("validator");
const postSchema = {
type: Connect.Schema.Types.ObjectId,
ref: "Post"
};
const experienceSchema = {
role: {
type: String,
required: true
},
company: {
type: String,
required: true
},
startDate: {
type: Date,
required: true
},
endDate: {
type: Date,
required: false
},
description: {
type: String,
required: false
},
area: {
type: String,
required: true
},
createdAt: {
type: Date,
default: Date.now,
required: false
},
updatedAt: {
type: Date,
default: Date.now,
required: false
},
username: {
type: String,
required: false
},
image: {
type: String,
required: false,
default: "https://via.placeholder.com/150"
}
};
const profileSchema = {
firstname: {
type: String,
required: true
},
surname: {
type: String,
required: true
},
email: {
type: String,
trim: true,
lowercase: true,
unique: true,
required: [true, "Email is required"],
validate: {
validator: string => isEmail(string),
message: "Provided email is invalid"
}
},
bio: {
type: String,
required: true
},
title: {
type: String,
required: true
},
area: {
type: String,
required: true
},
imageUrl: {
type: String,
required: false,
default: "https://via.placeholder.com/150"
},
username: {
type: String,
required: true,
unique: true
},
experience: [experienceSchema],
posts: [postSchema],
createdAt: {
type: Date,
default: Date.now,
required: false
},
updatedAt: {
type: Date,
default: Date.now,
required: false
}
};
const collectionName = "profile";
const profileSchemaModel = Connect.Schema(profileSchema);
const Profile = Connect.model(collectionName, profileSchemaModel);
module.exports = Profile;
I was able to make this for the embedded experience but not sure that correct for referenced collection:
const profileWithExperiences = await Student.aggregate([
{ $match: { username: res.username.username } },
{
$unwind: "$experience"
},
{
$match: {
"experience._id": new ObjectID(req.params.experienceId)
}
},
{
$project: {
username: 1,
experience: 1,
_id: 0
}
}
]);
I would like to see an example for referenced collections as it is confusing me how should I do that
[EDIT]
JSON for Profiles and Posts
{
"_id": ObjectId("5e2c98fc3d785252ce5b5693"),
"imageUrl": "https://i.pravatar.cc/300",
"firstname": "Jakos",
"surname": "Lemi",
"email": "lemi#email.com",
"bio": "My bio bio",
"title": "Senior IT developer",
"area": "Copenhagen",
"username": "Jakos",
"experience": [
{
"image": "https://via.placeholder.com/150",
"_id": ObjectId("5e3975f95fbeec9095ff3d2f"),
"role": "Developer",
"company": "Google",
"startDate": ISODate("2018-11-09T23:00:00.000Z"),
"endDate": ISODate("2019-01-05T23:00:00.000Z"),
"area": "Copenhagen",
"createdAt": ISODate("2020-02-04T13:47:37.167Z"),
"updatedAt": ISODate("2020-02-04T13:47:37.167Z")
},
{
"image": "https://via.placeholder.com/150",
"_id": ObjectId("5e3978bf5e399698e20c56d4"),
"role": "Developer",
"company": "IBM",
"startDate": ISODate("2018-11-09T23:00:00.000Z"),
"endDate": ISODate("2019-01-05T23:00:00.000Z"),
"area": "Copenhagen",
"createdAt": ISODate("2020-02-04T13:59:27.412Z"),
"updatedAt": ISODate("2020-02-04T13:59:27.412Z")
}
],
"createdAt": ISODate("2020-01-25T19:37:32.727Z"),
"updatedAt": ISODate("2020-02-04T23:14:37.122Z"),
"__v": NumberInt("0")
}
Post
{
"_id": ObjectId("5e3beb639e072afedd19dcef"),
"username": ObjectId("5e2c98fc3d785252ce5b5693"),
"image": "https://via.placeholder.com/150",
"text": "My awesome post",
"createdAt": ISODate("2020-02-06T10:33:07.22Z"),
"updatedAt": ISODate("2020-02-06T10:33:07.22Z"),
"reactions": [ ],
"__v": NumberInt("0")
}
Output expected:
{
"username": "Jakos",
"postsCount": [1],
"posts": [
{
"_id": ObjectId("5e3beb639e072afedd19dcef"),
"image": "https://via.placeholder.com/150",
"text": "My awesome post",
"createdAt": ISODate("2020-02-06T10:33:07.22Z"),
"updatedAt": ISODate("2020-02-06T10:33:07.22Z"),
"reactions": [ ],
"__v": NumberInt("0")
}
]
}
I want to see all the posts related to that username

Answer 1

You can use the $lookup aggregation to join collections.
db.profiles.aggregate([
{
$match: {
username: "Jakos"
}
},
{
$lookup: {
from: "posts", //the name of the posts collection, change this if it is different
localField: "_id",
foreignField: "username",
as: "posts"
}
},
{
$project: {
username: 1,
posts: 1,
postsCount: {
$size: "$posts"
},
_id: 0
}
}
])
Playground
For mongoose it should be like this in your app:
const profileWithExperiences = await Student.aggregate([
{ $match: { username: res.username.username } },
{
$unwind: "$experience"
},
{
$lookup: {
from: "posts", //the name of the posts collection, change this if it is different
localField: "_id",
foreignField: "username",
as: "posts"
}
},
{
$project: {
username: 1,
posts: 1,
postsCount: {
$size: "$posts"
},
_id: 0
}
}
]);

Answer 2

Try to get like this i am getting data from two table with the use of node and mongodb.
var param = {};
param['user_id']=id;
var search={ user_id:param.user_id,status: [ 'Pending', 'Accepted' ] };
var output={};
output = await JobRequest.find(search);
if(output !=0)
{
var JSon=await JobRequest.aggregate([
{$match: { user_id: {$gte:id}} },
{
"$project": {
"employee_id": {
"$toObjectId": "$employee_id"
},
"service_id": {
"$toObjectId": "$service_id"
},
"createdDate": {
"$toString": "$createdDate"
},
"chat_status": {
"$toString": "$chat_status"
},
"status": {
"$toString": "$status"
},
"delivery_address": {
"$toString": "$delivery_address"
},
"delivery_lat": {
"$toString": "$delivery_lat"
},
"delivery_lang": {
"$toString": "$delivery_lang"
},
}
},
{
$lookup:
{
from: "employees",
localField: "employee_id",
foreignField: "_id",
as: "employee_details"
}
},
{
$lookup:
{
from: "services",
localField: "service_id",
foreignField: "_id",
as: "service_details"
}
}
]);