Associations named using a string cannot be included in a scope
If you defined your association via
class Article
belongs_to "category"
end
and you try
Article.scoped(:include => :category)
you will get an error message
in `preload_one_association': Association named 'category' was not found; perhaps you misspelled it? (ActiveRecord::ConfigurationError)
Solution
Always define your assocations via symbol
class Article
belongs_to :category
end
Related cards:
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...
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...
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...
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....
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...
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...
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...
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...
Guide to localizing a Rails application
Localizing a non-trivial application can be a huge undertaking. This card will give you an overview over the many components that are affected.
When you are asked to give an estimate for the effort involved, go through the list below and check wh...
Differences between transactions and locking
Web applications can be used by multiple users at the same time. A typical application server like Passenger has multiple worker processes for a single app. In a distributed deployment setup like we use at makandra you w...