Posts on Arto's dev time by-products

How I Built a Vehicle Cost Comparison Tool That Doesn't Ignore Depreciation

Sat, 19 Sep 2026 00:00:00 +0000

I was replacing a 2014 petrol MPV with a used EV. Along the way I collected insurance quotes, checked the vehicle tax bracket, asked for a battery health certificate, got a trade-in offer, and compared a cash price against a dealer’s financing plan. Somewhere in the middle of all that I wanted one simple thing: a single number telling me what switching would actually cost per year, compared to just keeping the car I already had.

How to Resolve Vitest `EMFILE: too many open files` Errors on a High Thread Count Machine

Wed, 02 Jul 2025 00:00:00 +0000

If you’re running your Vitest suite on a high thread count machine—like an 8-core or 16-core development machine—you may encounter a frustrating error that looks like this:

EMFILE: too many open files

This issue can be cryptic at first, especially when your system doesn’t seem anywhere near running out of resources. But the root cause might not be in your system limits—it could be in your import statements.

The Unexpected Culprit: Named Imports from MUI

In my case, after hours of digging, I discovered that the error was caused by using named imports from Material UI (MUI) components and icons. These named imports, when used across many test files, were triggering Vitest to open an excessive number of files behind the scenes.

How to stream audio in local network with FFMpeg?

Thu, 31 Oct 2024 00:00:00 +0000

Streaming audio locally can be useful for broadcasting live audio to multiple devices or applications within the same network. With FFmpeg, this setup becomes simple, allowing you to stream audio directly from your microphone to any player that supports UDP streaming, like VLC. This guide explains how to set up FFmpeg on Windows, configure a low-latency stream, and tune it for optimal performance.

Step 1: Install FFmpeg on Windows

To use FFmpeg on Windows, you’ll need to download and install it. Follow these steps:

How to Update Nested Array Subdocuments Using Main Document Field with Mongoose

Fri, 05 Jul 2024 00:00:00 +0000

Updating nested array subdocuments based on a field in the main document is a common task when working with MongoDB and Mongoose. Here’s a simple guide and example to help you accomplish this.

Plan

Use Model.updateMany() or Model.findOneAndUpdate() to update multiple or a single document.
Use an aggregation pipeline ([{}]) as the second argument to reference document fields.
Use the $set stage within the pipeline to update the nested array.
Use the $$ROOT variable to reference fields from the main document.

Example

Assume you have a User model where each user has an array of posts, and you want to set each post’s authorName field based on the user’s name field.

How to Download Streaming Video Using ffmpeg

Wed, 03 Jul 2024 00:00:00 +0000

How to Download Streaming Video Using ffmpeg

Streaming video has become ubiquitous, but sometimes you might want to save a portion of a video for offline viewing or archival purposes. One powerful tool for this task is ffmpeg, a versatile command-line program for handling multimedia data. In this guide, we’ll walk you through the process of installing ffmpeg and using it to download streaming video.

Installing ffmpeg

Before you can use ffmpeg, you need to install it on your system. One of the simplest ways to install ffmpeg on Windows is via Chocolatey, a package manager for Windows. Follow these steps to install ffmpeg:

How to sanitize NestJS API responses with Interceptor

Thu, 11 Jan 2024 00:00:00 +0000

In any API development project, ensuring that sensitive or unnecessary data is not exposed in the responses is crucial for security and efficiency. In NestJS, interceptors provide a powerful way to manipulate the flow of data. In this blog post, we’ll explore how to use an interceptor to sanitize API responses by removing specific properties. We’ll also look at how to write tests to ensure the interceptor behaves as expected.

How to resolve Intel Graphics Command Center port conflict

Wed, 10 Jan 2024 00:00:00 +0000

For developers working on .NET Core and other development servers, encountering port conflicts can be a common issue. Recently, I came accross with the default port (5000) used for local development server and the Intel(R) Graphics Command Center server. In this blog post, I’ll introduce a workaround that involves editing the Windows registry to resolve the conflict and ensure smooth development processes.

Understanding the Issue:

The Intel(R) Graphics Command Center server, specifically the OneApp.IGCC.WinService.exe executable, by default, utilizes port 5000. However, this port is commonly used for development servers in the .NET Core ecosystem and other software development environments. When both the Intel(R) Graphics Command Center server and a development server attempt to bind to port 5000 simultaneously, a conflict arises.

How to create a custom React hook for locale-specific date formatting

Fri, 22 Dec 2023 00:00:00 +0000

In this post, I will show you how to create a custom React hook that provides locale-specific date formatting functions. This hook can be useful if you want to display dates and times in different languages and formats depending on the user’s preferences.

What is a custom React hook?

A custom React hook is a function that starts with the word use and may call other hooks. Custom hooks let you reuse stateful logic between components without duplicating code or introducing complex patterns. You can learn more about custom hooks from the official React documentation (1) or this tutorial (2).

How to capitalize each word of a string in TypeScript

Tue, 12 Sep 2023 00:00:00 +0000

In the world of web development and application design, small details can make a big difference. One such detail is the proper capitalization of text, especially when dealing with user-generated content or dynamic data. Ensuring that text appears neat and consistent can significantly enhance the user experience. In this blog post, we’ll introduce you to a handy utility function called capitalizeEachWord that can help you achieve just that.

What is `capitalizeEachWord`?

The capitalizeEachWord function is a TypeScript utility that capitalizes the first letter of each word in a given string while keeping the rest of the letters in lowercase. This function also allows you to specify a word separator, which can be useful when dealing with text containing multiple words separated by a character or whitespace.

How to scrape all links from a website

Tue, 02 May 2023 00:00:00 +0000

Simply copy-paste the following one-liner to Chrome Dev Tools. To limit the results, set the reg exp placeholder to contain some sensible value, or replace the function call with return value true.

Array.prototype.slice.call( document.getElementsByTagName('a'), 0 )
  .map(i => i.href)
  .filter(i => i.match('reg exp placeholder'))
  .forEach(i => console.log(i))

Here is an explanation for what it does:

Selects all the elements on the document.
Converts the HTMLCollection object returned by getElementsByTagName into an Array by using the Array.prototype.slice method.
The slice() method returns a shallow copy of a portion of an array into a new array object selected from begin to end (end not included) where begin and end represent the index of items in that array. Here, it selects all the items starting from index 0 to the end of the array by passing 0 as the first argument to slice() method.
Maps the href attribute of each of the selected elements into an array using the Array.prototype.map method. The resulting array will contain a list of all the href attributes of the elements.
Filters the array obtained in the previous step by selecting only those elements that match a regular expression pattern. The pattern is a placeholder and should be replaced with an actual regular expression to match the desired elements. This is achieved using the Array.prototype.filter method.
Loops through the resulting filtered array using the forEach() method and logs each element to the console using console.log() method. This will output the list of href attributes of the elements that match the given regular expression pattern to the console.

How to bump version number on Git push for projects using npm

Sat, 01 Apr 2023 00:00:00 +0000

Note: This works only from command line as user feedback is needed from keyboard to know which part of the version number to bump. It should not break pushing from a GUI tool (e.g. TortoiseGit), but you will not be prompted to update the version number. The positive thing is that the version change is done neatly as a separate commit.

Install husky as dev-dependency

See instructions.
Add the following script into new file .husky/pre-push

How to collect all npm licenses from multiple subdirectories with Powershell

Wed, 29 Mar 2023 00:00:00 +0000

Install license-report (https://www.npmjs.com/package/license-report)

npm install -g license-report

run the script

Get-ChildItem -Directory | foreach { $_ >> ./licenses.csv ; license-report --output=csv --only=prod --package=./$_/package.json >> ./licenses.csv }

You can use the same idea to run other stuff in subdirectories. Just replace the command. Here is an example of git pull.

Get-ChildItem -Directory -Force -Recurse *.git | ForEach-Object { cd $_.Parent.FullName; Write-Host $_.Parent.FullName; git pull }

How to update a specified item in a nested array with Mongoose

Sat, 11 Feb 2023 00:00:00 +0000

In this blog post, we’ll go over how to update a specified item in a nested array inside a Mongoose document.

##Setting up the environment

First, let’s set up the environment by creating a Mongoose schema and model. Here’s an example schema that has a nested array of items:

const mongoose = require('mongoose');

const schema = new mongoose.Schema({
  items: [{
    name: String,
    quantity: Number
  }]
});

const Model = mongoose.model('Model', schema);

##Updating a specified item in a nested array

How to access your Synology NAS services over public Web

Thu, 09 Feb 2023 10:00:00 +0000

To access the Syonology NAS ports outside of your local network, you need to set up DDNS, a wildcard certificate, and a reverse proxy to support HTTPS access.

DDNS

Go to Control Panel / External Access / DDNS. Click Add.

Make the following selections:

Service Provider: Synology
Hostname: yourname.synology.me
Username/Email: <your email>
Password: <make it up>
Exteral address: no need to change

Wildcard certificate

Go to Control Panel / Security / Certificate. Click Add.

How to find out your UID and GID on Synology NAS

Thu, 09 Feb 2023 10:00:00 +0000

The UID and GID values for default user on Synlogy NAS are usually 1026 and 100. There is a very simple way to check the values as follows:

Create a new Scheduled task asn User-defined script
Name the script whatever you see fit
Set it to be not repeating
Set it to send run details to your email
Write the script:
```
id
```
Not too complex, huh?
Run it and soon enough, you will receive the email containing the UID and GID values.

These values will be needed to install some Docker containers, for instance the Codeserver.

How to Set Up a Codeserver on Synology NAS

Thu, 09 Feb 2023 10:00:00 +0000

Have you ever missed the VSCode on your tablet? Now there is a solution: run the VSCode on your NAS at home and access it with a browser. That will be possible when you run the Codeserver Docker container on your NAS.

Before you do this, you probably want to set up a wildcard certificate and a proxy server on your NAS. That will enable you to access the NAS outside your local network using HTTPS. How to do it, check this: How to Set Up Wildcard Certificate and Reverse Proxy on Synology NAS

How to use ConfigService in NestJS in application bootstrap

Thu, 09 Feb 2023 00:00:00 +0000

You might want to access the configuration, for example to set the microservice configuration based on the values from the configuration service.

One way to do this is to create an application context from the AppModule.

  const appContext = await NestFactory.createApplicationContext(BootstrapConfigModule)
  const configService = appContext.get(ConfigService)
  const SERVICE_PORT = configService.get('SERVICE_PORT')
  appContext.close()

But a better idea is to use a “temporary” module to avoid double instantiation of the whole app. See a full example below.

import { Module } from '@nestjs/common'
import { ConfigService } from '@nestjs/config'
import { NestFactory } from '@nestjs/core'
import { MicroserviceOptions, Transport } from '@nestjs/microservices'

import { AppModule } from './app.module'

// Bootstrap configuration module is needed to avoid
// doing the DI resolution twice
@Module({
  providers: [ConfigService],
  exports: [ConfigService],
})
class BootstrapConfigModule {}

async function bootstrap() {
  const appContext = await NestFactory.createApplicationContext(BootstrapConfigModule)
  const configService = appContext.get(ConfigService)
  const SERVICE_PORT = configService.get('SERVICE_PORT')
  appContext.close()
  const app = await NestFactory.createMicroservice<MicroserviceOptions>(AppModule, {
    transport: Transport.TCP,
    options: {
      port: SERVICE_PORT,
    },
  })
  await app.listen()
}
bootstrap()

Why would you need to use the configuration service instead of process.env you might ask. Well, while that may work, it doesn’t offer any type safety or support for fallbacks.

How to merge a nested list in Mongo document with another found in adjacent collection

Sun, 05 Feb 2023 08:04:11 +0200

Let’s consider a situation where you have two collections, houses and people. Each house has a collection of key holders, which link to the persons collection with their IDs. Key holders list also holds information when the key was given for the identified person.

In bson, the situation in the database looks like this:

{
  "houses": [
    {
      "_id": ObjectId("5fba17c1c4566e57fafdcd7e"),
      "address": "Main street 1",
      "keyHolders": [
        {
          "keyDelivered": "2022-02-02T02:02:02",
          "personId": "5fbb5ab778045a985690b5fc"
        },
        {
          "keyDelivered": "2021-01-01T01:01:01",
          "personId": "5fbb5ab778045a985690b5fd"
        }
      ]
    },
    {
      "_id": ObjectId("5fba17c1c4566e57fafdcd7f"),
      "address": "Broadway 3",
      "keyHolders": [
        {
          "keyDelivered": "1993-03-03T03:03:03",
          "personId": "5fbb5ab778045a985690b5fc"
        }
      ]
    }
  ],
  "persons": [
    {
      "_id": ObjectId("5fbb5ab778045a985690b5fc"),
      "name": "Jack Bauer",
      
    },
    {
      "_id": ObjectId("5fbb5ab778045a985690b5fd"),
      "name": "James Bond",
      
    }
  ]
}

You can also do some mapping for the source list, for instance convert foreign keys from strings to ObjectIds.

How to Copy a Collection of Documents to Another Database with mongosh

Sat, 04 Feb 2023 09:32:28 +0200

If you need to copy a collection of documents from one Mongo collection to another, you can use the mongodump and mongorestore. But if the source database is in the same instance as the target, then you may be able to take a shortcut with mongosh.

Here is the script to use:

db.<source collection>.find().forEach(function(d){ db.getSiblingDB('<dest db>')['<dest collection>'].insert(d); });

For example, if you are copying all documents from current databases cars collection to a database called another-db’s collection vehicles:

How to set up a blog with Hugo and GitHub Pages in 10 minutes

Fri, 03 Feb 2023 15:04:11 +0200

So you want to set up a blog. Here is how to do it in 10 minutes or less. For me, it took a little more time, just to make sure for you it would not. And actually, even for me, most of the time was used to write this post.

So here we go, you have 40 for each step.

Create GitHub account if you do not have one yet
Create new GitHub repository named <your GitHub username>.github.io
On your local development environment, create a folder to work in, run npm install hugo-bin --save-dev to install Hugo CLI
Clone your GitHub repository under the same directory git clone https://github.com/<your username>/<your username>.github.io.git
Run npx hugo new site <your username>.github.io
Navigate to the repository root directory cd <your username>.github.io
Add a theme as Git Submodule: git submodule add --depth=1 https://github.com/adityatelange/hugo-PaperMod.git themes/PaperMod
Update config.toml by adding the theme = 'PaperMod' option (and add a name for the site while at it)
Also update config.toml with your own baseUrl, e.g. baseURL = 'https://<your GitHub username>.github.io/'
Run npx hugo new posts/initial-post.md
Edit the initial post and when ready to publish, remove the draft tag

Add the following into .github\workflows\gh-pages.yml file in the repository

name: github pages

on:
push:
    branches:
    - main  # Set a branch that will trigger a deployment
pull_request:

jobs:
    deploy:
        runs-on: ubuntu-22.04
        steps:
        - uses: actions/checkout@v3
            with:
            submodules: true  # Fetch Hugo themes (true OR recursive)
            fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod

        - name: Setup Hugo
            uses: peaceiris/actions-hugo@v2
            with:
            hugo-version: 'latest'
            # extended: true

        - name: Build
            run: hugo --minify

        - name: Deploy
            uses: peaceiris/actions-gh-pages@v3
            if: github.ref == 'refs/heads/main'
            with:
            github_token: ${{ secrets.GITHUB_TOKEN }}
            publish_dir: ./public

Create a branch named gh-pages in GitHub
Check which branch is used for GitHub pages publishing in your GitHub repository, set it to gh-pages
Set in GitHub Settings > Actions > General: Workflow permissions to Read and write permissions
Push to Git remote using the main branch
Make sure the deployment went smoothly, and enjoy the result in https://<your GitHub username>.github.io

Posts on Arto's dev time by-products

How I Built a Vehicle Cost Comparison Tool That Doesn't Ignore Depreciation

How to Resolve Vitest `EMFILE: too many open files` Errors on a High Thread Count Machine

The Unexpected Culprit: Named Imports from MUI

How to stream audio in local network with FFMpeg?

Step 1: Install FFmpeg on Windows

How to Update Nested Array Subdocuments Using Main Document Field with Mongoose

Plan

Example

How to Download Streaming Video Using ffmpeg

How to Download Streaming Video Using ffmpeg

Installing ffmpeg

How to sanitize NestJS API responses with Interceptor

How to resolve Intel Graphics Command Center port conflict

How to create a custom React hook for locale-specific date formatting

What is a custom React hook?

How to capitalize each word of a string in TypeScript

What is capitalizeEachWord?

How to scrape all links from a website

How to bump version number on Git push for projects using npm

How to collect all npm licenses from multiple subdirectories with Powershell

How to update a specified item in a nested array with Mongoose

How to access your Synology NAS services over public Web

DDNS

Wildcard certificate

How to find out your UID and GID on Synology NAS

How to Set Up a Codeserver on Synology NAS

How to use ConfigService in NestJS in application bootstrap

How to merge a nested list in Mongo document with another found in adjacent collection

How to Copy a Collection of Documents to Another Database with mongosh

How to set up a blog with Hugo and GitHub Pages in 10 minutes

What is `capitalizeEachWord`?