Mongoose GroupBy with Populate - mongodb

Question

i have User document and and Category document which is connected to shop document which look like
var ShopSchema = mongoose.Schema(
{
shopName: {
type: String,
required: [true, 'A Shop must have name'],
},
phone: {
type: String,
validate: [validator.isMobilePhone,"Phone number is not a valid number"],
required: [true, 'A Shop must have hepline number'],
},
shopStatus: {
type: Boolean,
default: false,
select: false
},
managerId:{
type: mongoose.Schema.ObjectId,
ref:'User',
require: [true,'Shop must have to a manager!']
},
createdAt:{
type:Date,
default: Date.now()
},
shopCategory:{
type: mongoose.Schema.ObjectId,
ref:'Category',
require: [true,'Shop must have a Category!']
},
},
{
toJSON: { virtuals: true },
toObject: { virtuals: true }
}
);
const Shop = mongoose.model("Shop", ShopSchema);
Now i am writing a query to get managers shop(groupBy managerId) with populate of Manager and Category data. but i am getting empty array everytime.
const doc = await Shop.aggregate([
{
$match: { shopStatus: {$ne: false} }
},
{
$group: {
_id:'$managerId',
numofShop: {$sum: 1},
shopCategory: {$first: "$shopCategory"}
}
},
{
$lookup: {
from: "User",
localField : "_id",
foreignField: "_id",
as: "Manager"
}
},
{
$lookup: {
from: "Category",
localField : "shopCategory",
foreignField: "_id",
as: "Category"
}
},
])
here is how my final result look like but this is an empty array.
{
"_id": "5f467660f630e804ec07fad8",
"numofShop": 2,
"Manager": [],
"Category": []
},
{
"_id": "5f44d2f4ff04993b40684bf9",
"numofShop": 1,
"Manager": [],
"Category": []
}
I want to find All shops groupBy managerId(Who own it). there is field of managerId referencing to User document who created this shop. i want data like this
{
"_id": "5f44d2f4ff04993b40684bf9",
"Manager": {},//this is populated through User Schema
"numofShop": 1,
"Shop": [
{
"shopName":"Grocery Shop",
"phone" : "111111",
"shopCategory" :{"_id": "","name":"Electronics"}
}
]
}
.....
.....
Find Example Data here
Shops- http://txt.do/1fwi0
3 shops created by two users
User - http://txt.do/1fwio
Categories- http://txt.do/1fwij

Answer 1

There are 2 fixes,
in second lookup you have no shopCategory field in localField because you have not defined shopCategory in $group,
{
$group: {
_id:'$managerId',
numofShop: {$sum: 1},
shopCategory: { $first: "$shopCategory" } // define here
}
},
in first lookup with user collection, there is no managerId field and you have assigned in _id field, then you can use _id in localField,
{
$lookup: {
from: "User",
localField : "_id", // change this from managerId
foreignField: "_id",
as: "Manager"
}
},
Updated things after updated question, Playground1, Playground2
for your second edit, you can't put condition for populate in find method, how to put condition in populate, you can follow the answer1 and answer2