How to fix: Unable to read files from a VirtualBox shared host folder
When you want to copy/move from a shared folder (on Windows guests, for example) and it fails with absurd error messages (lots of text or an error about the target being read-only), you are probably running on Guest Additions that no longer match your VirtualBox version.
Fix: install the latest VirtualBox Guest Additions in your guest machine.
Note that you need to make sure you are using the correct ISO.
Related cards:
How to make changes to a Ruby gem (as a Rails developer)
At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (> 1M downloads), active_type (> 1M downloads), and geordi (> 200k downloads)
Developing a Ruby gem is different from developing Rails applications, w...
Async control flow in JavaScript: Promises, Microtasks, async/await
Slides for Henning's talk on Sep 21st 2017.
Understanding sync vs. async control flow
Talking to synchronous (or "blocking") API
print('script start')
html = get('/foo')
print(html)
print('s...
JavaScript without jQuery (presentation from 2019-01-21)
Summary
- We want to move away from jQuery in future projects
- Motivations are performance, bundle size and general trends for the web platform.
- The native DOM API is much nicer than it used to be, and we can polyfill the missing pieces
- Un...
How to: Upgrade CarrierWave to 3.x
While upgrading CarrierWave from version 0.11.x to 3.x, we encountered some very nasty fails. Below are the basic changes you need to perform and some behavior you may eventually run into when upgrading your application. This aims to save you some...
Delivering Carrierwave attachments to authorized users only
Preparation
To attach files to your records, you will need a new database column representing the filename of the file. To do this, add a new migration (rails g migration <name>) with the following content:
class AddAttachmentToNotes...
The JavaScript Object Model: A deep dive into prototypes and properties
Speaker today is Henning Koch, Head of Development at makandra.
This talk will be in German with English slides.
Introduction
As web developers we work with JavaScript every day, even when our backend code uses anothe...
How to create giant memory leaks in AngularJS (and other client-side JavaScript)
This guide shows how to create an AngularJS application that consumes more and more memory until, eventually, the browser process crashes on your users.
Although this guide has been written for Angular 1 originally, most of the advice is relevant...
Fixing flaky E2E tests
An end-to-end test (E2E test) is a script that remote-controls a web browser with tools like Selenium WebDriver. This card shows basic techniques for fixing a flaky E2E test suite that sometimes passes and sometimes fails.
Although many examples ...
Lightning Talk: Coverage based Test Case Prioritization in Ruby on Rails
For my computer science bachelor's thesis I programmed and evaluated a CLI Test Case Prioritization (TCP) tool for makandra. It has been written as a Ruby Gem and was tested and evaluated against one Ruby on Rails project....
The Ruby Object Model
In Ruby (almost) everything is an Object. While this enables a lot of powerful features, this concept might be confusing for developers who have been programming in more static languages, such as Java or C#. This card should help understanding t...