Mongoose aggregate by date and values - node.js

Question

I cannot solve a problem I am having on a project.
First of all, I have a Schema called Emotions, shown below:
import mongoose from 'mongoose';
const EmotionSchema = new mongoose.Schema({
classification: {
type: String,
required: true,
},
probability: {
type: Number,
required: true,
},
user: {
type: mongoose.Schema.Types.ObjectId,
ref: 'User',
}
}, {
timestamps: true,
});
export default mongoose.model('Emotion', EmotionSchema);
And some data like this:
[
{
"_id": "61144a393c532f066725bd24",
"classification": "Feliz",
"probability": 0.98,
"user": "60eecfeba0810013e750cdbc",
"createdAt": "2021-08-11T22:07:53.331Z",
"updatedAt": "2021-08-11T22:07:53.331Z",
"__v": 0
},
{
"_id": "61144a46d30bd006fa2be702",
"classification": "Feliz",
"probability": 0.98,
"user": "60eecfeba0810013e750cdbc",
"createdAt": "2021-08-11T22:08:06.618Z",
"updatedAt": "2021-08-11T22:08:06.618Z",
"__v": 0
},
{
"_id": "611541dd62a7f214afab3ceb",
"classification": "Triste",
"probability": 0.9,
"user": "60eecfeba0810013e750cdbc",
"createdAt": "2021-08-12T15:44:29.150Z",
"updatedAt": "2021-08-12T15:44:29.150Z",
"__v": 0
},
{
"_id": "611541f762a7f214afab3cf5",
"classification": "Raiva",
"probability": 0.86,
"user": "60eecfeba0810013e750cdbc",
"createdAt": "2021-08-12T15:44:55.909Z",
"updatedAt": "2021-08-12T15:44:55.909Z",
"__v": 0
},
{
"_id": "6115420362a7f214afab3cf7",
"classification": "Neutro",
"probability": 0.99,
"user": "60eecfeba0810013e750cdbc",
"createdAt": "2021-08-12T15:45:07.297Z",
"updatedAt": "2021-08-12T15:45:07.297Z",
"__v": 0
},
{
"_id": "6115420462a7f214afab3cf9",
"classification": "Neutro",
"probability": 0.99,
"user": "60eecfeba0810013e750cdbc",
"createdAt": "2021-08-12T15:45:08.002Z",
"updatedAt": "2021-08-12T15:45:08.002Z",
"__v": 0
},
{
"_id": "611543d252be9a187c380e5d",
"classification": "Feliz",
"probability": 0.91,
"user": "60eecfeba0810013e750cdbc",
"createdAt": "2021-08-12T15:52:50.599Z",
"updatedAt": "2021-08-12T15:52:50.599Z",
"__v": 0
}
]
What I want is:
First group each of these records by day.
Afterwards, count the values ​​by classification, but separating these classifications.
Something like that:
[
{
"_id": "12/08/2021",
"feliz": 1,
"triste": 1,
"raiva": 1,
"neutro": 2,
"surpreso": 0,
},
{
"_id": "11/08/2021",
"feliz": 2,
"triste": 0,
"raiva": 0,
"neutro": 0,
"surpreso": 0,
}
]
I did something like that, but it's only working for a value, eg "Feliz".
In code:
Emotion.aggregate([
{ $match:
{
user: user._id,
classification: "Feliz"
}
},
{ $group: {
_id : { $dateToString: { format: "%d/%m/%Y", date: "$createdAt" } },
feliz: { $sum: 1 }
}},
], function(err, results) {
if (err) throw err;
return res.json(results);
})
And it returns:
[
{
"_id": "12/08/2021",
"feliz": 1
},
{
"_id": "11/08/2021",
"feliz": 4
}
]
One more question:
From the Client-side, I always get values ​​for "classification" like:
"Feliz", "Triste", "Surpreso", "Raiva", "Neutro".
So is it better to add an enum to my schema "Emotion"?
(Sorry for my English, i hope you understand).

Answer 1

$group by createdAt date and classification, count sum
$group by createdAt only and construct the array of classification and count in key-value pair
$arrayToObject to convert above key-value pair array of object to an object format
Emotion.aggregate([
{
$match: {
user: user._id,
classification: "Feliz"
}
},
{
$group: {
_id: {
createdAt: {
$dateToString: {
format: "%d/%m/%Y",
date: "$createdAt"
}
},
classification: "$classification"
},
count: { $sum: 1 }
}
},
{
$group: {
_id: "$_id.createdAt",
classifications: {
$push: {
k: "$_id.classification",
v: "$count"
}
}
}
},
{
$addFields: {
classifications: {
$arrayToObject: "$classifications"
}
}
}
],
function(err, results) {
if (err) throw err;
return res.json(results);
})
Playground
Note: this will not return classification when count is 0! You need to do this after query in js.
One more question: From the Client-side, I always get values ​​for "classification" like: "Feliz", "Triste", "Surpreso", "Raiva", "Neutro". So is it better to add an enum to my schema "Emotion"?
It is up to your project requirement, you can set these values in enum to restrict the input.