CODEWITHSUNDEEP
javascriptnode.jsmongoose
jodoox
jodoox

Reputation: 829

Mongoose: update Array with item-wise maximum

In Mongoose, how can I update an Array property with item-wise max, and have default null upon instantiation?

I have a Mongodb collection of timeseries where values are stored in a fixed-length array (1 item per minute, 1 document per day). 

{
  'series': '#1',
  'values': [null, null, 1, 2, 3, -4, ... ] //24h*60min=1440 items
}

I am doing computations on ~x000 timeseries on a rather high frequency (100ms), and I want to store the maximum that each of these series met during every minute. For some reason, when I update the documents, Mongoose transforms the .values property into an object, which is more space-consuming and less efficient for my use. 

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/test_db');

const TestSchema = new mongoose.Schema({
  series: String,
  values: {type: Array, default: Array(5).fill(null), required: true},
});
const Test = mongoose.model('Test', TestSchema);

async function update({series, values}){ //called every minute or so
    let updated = {    };
    for (let {i, v} of values)  {
        if (updated[`values.${i}`] && updated[`values.${i}`]<v) updated[`values.${i}`]= v;
        if (!updated[`values.${i}`]) updated[`values.${i}`]=v;
    };

    return mongoose.connection.models.Test.updateOne(
        {'series':series},
        {   '$max': updated },
        { upsert: true, strict: true, new: true}
    );
}

async function test_update(){
    //get rid of previous tentatives
    await mongoose.connection.models.Test.deleteMany({});
    let s = new Test({series: '#1'});
    await update({series:'#1', values:[{i:3, v:-3},{i:4, v:6},{i:2, v:4}, {i:2, v:7}]});
}

test_update();

I would want my script to return 

 {
    "_id" : ObjectId("5cb351d9d615cd456bd6a4ed"),
    "series" : "#1",
    "__v" : 0,
    "values" : [null, null, 7, -3, 6]
}

and not the current result below: 

 {
    "_id" : ObjectId("5cb351d9d615cd456bd6a4ed"),
    "series" : "#1",
    "__v" : 0,
    "values" : { //values is an Object, not an Array
        "2" : 7,
        "3" : -3,
        "4" : 6
    }
}

Thanks!

Upvotes: 1

Views: 52

Answers (1)

Mike Rudge
Mike Rudge

Reputation: 206

`I THINK it may be your schema

Instead of:

const TestSchema = new mongoose.Schema({
  series: String,
  values: {type: Array, default: Array(5).fill(null), required: true},
});

You should make values an array of numbers like this

const TestSchema = new mongoose.Schema({
  series: String,
  values: {type: [Number], default: Array(5).fill(null), required: true},
});

Upvotes: 1

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