ActiveRecord: When aggregating nested children, always exclude children marked for destruction
When your model is using a callback like before_save or before_validation to calculate an aggregated value from its children, it needs to skip those children that are #marked_for_destruction?. Otherwise you will include children that have been ticked for deletion in a nested form.
Wrong way
class Invoice
has_many :invoice_items
accepts_nested_attributes_for :invoice_items, :allow_destroy => true # the critical code 1/2
before_save :calculate_and_store_amount # the critical code 2/...
Git: Merge a single commit from another branch
This is called "cherry-picking".
git cherry-pick commit-sha1
Note that since branches are nothing but commit pointers, cherry-picking the latest commit of a branch is as simple as
git cherry-pick my-feature-branch
Be aware of Cherry picks to production branches!
How to fill in multiple lines in a textarea with cucumber
If you want to fill in textareas with multiple lines of text (containing line breaks) you can use Cucumber's docstrings:
And I fill in "Comment" with:
"""
This is a long comment.
With multiple lines.
And paragraphs.
"""
The step definition is part of the spreewald gem
What edge_rider gives you
edge_rider is Power tools for ActiveRecord relations (scopes). Please note that some of the functions edge_rider provides have native implementations in newer rails versions.
Relation#traverse_association(*names)
Edge Rider gives your relations a method #traverse_association which returns a new relation by "pivoting" around a named association. You can traverse multiple associations in a single call. E.g. to turn a relation of posts into a relation of all posts of their authors:
```
posts…
We no longer maintain the rspec_candy gem
We no longer maintain rspec_candy.
Most of the functionality of rspec_candy is now built into modern versions of RSpec.
Do not use transparent PNGs for iOS favicons
Safari on iOS accepts an apple-touch-icon favicon that is used for stuff like desktop bookmarks. Always define a solid background color for them.
If you use PNGs with a transparent background, Safari will use just set a black background on your pretty icon. This is almost never what you want.
You can fix that by applying a white background via ImageMagick like this:
convert a...
Optimizing images for web
For webpages to load fast it's recommended to optimize images. Ideally an image's file size should be as small as possible while still being of decent quality. This card demonstrates two command line tools for image optimization
Use identify to fetch information about pictures. convert can change size/quality and strip meta information. Both commands are supplied by ImageMagick.
```text
$ identify in.jpg
in.jpg JPEG 294x440 294x440+0+0 8-bit sRGB 92.8KB 0.000u 0:00.000
$ convert in.jpg -resize x220 -strip -quality 85 out.jpg
$ identify…
JavaScript “Stale Practices” | benmccormick.org
The linked article lists a number of techniques that were best practices with ES5, but have better alternatives in modern JavaScript.
Best practices don’t last forever. This is especially true when a field is changing fast, and JavaScript development has changed a lot over the past 10 years. The old best practices go stale, and new ones take their place. Here are 5 JavaScript best practices that have gone stale recently.
3 ways to run Spring (the Rails app preloader) and how to disable it
spring ...
The most obvious way to use spring is to call it explicitly:
spring rails console
spring rake db:migrate
Binstubs
Binstubs are wrapper scripts around executables. In Rails they live inside bin/. If you run spring binstub --all, your binstubs will be using Spring.
bin/rails console
bin/rake db:migrate
bundle exec rails ...
You would not expect, but this also runs with Spring. However, bundle exec rake does not. Better use binstubs :)
```
bundle exec rails co…
Updated: Webpacker: Configuring browser compatibility
Setting the UglifyJS options should only happen in config/webpack/production.js because UglifyjS is only available in production environment. Otherwise you will get a Error: Item UglifyJs not found when starting a rails server for development.
Note: rake tasks like webpacker:compile set NODE_ENV=production whereas starting the rails server has NODE_ENV=development configured. So you will not get the error on compiling via rake.
We no longer maintain the safe_cookies gem
We no longer maintain safe_cookies.
Also see reasons and alternatives.
Cucumber features as documentation
Cucumber allows for prose in features and scenarios. Example:
Feature: Cancel account
There are several ways to cancel a user account. Admins need to
do it in complex cases, but normally, users can do it themselves.
Scenario: User cancels his own account
Users should be able to cancel an account themselves, so the
admins do not need to do it.
Given a user account for "willy@astor.de"
When I sign in as "willy@astor.de"
And I follow "Cancel account"
Then I should see "Account canceled"
B…
Devise: Invalidating all sessions for a user
Background information about session storage in Rails
Rails has a default mechanism to store the session in the CookieStore. This is a cookie which holds the entire user session hash in the browser. This cookie is serialized, encoded with base64, and signed.
How Devise handles authentication
Devise uses this CookieStore. To track a users session, a salt is stored in the session cookie when a user logs in.
When a user logs out this CookieStore is overwrit…
Why has_many :through associations can return the same record multiple times
An association defined with has_many :through will return the same record multiple times if multiple join models for the same record exist. To prevent this, you need to add ->{ uniq } as second argument to has_many (below Rails 4 it is a simple option: has_many :xyz, :uniq => true).
Example
Say you have an Invoice with multiple Items. Each Item has a Product:
class Invoice < ActiveRecord::Base
has_many :items
has_many :products, :through => :items
end
class Item < ActiveRecord::Base
b...