Dealing with I18n::InvalidPluralizationData errors
When localizing model attributes via I18n you may run into errors like this:
I18n::InvalidPluralizationData: translation data { ... } can not be used with :count => 1. key 'one' is missing.
They seem to appear out of the blue and the error message is more confusing than helpful.
TL;DR A model (e.g. Post) is lacking an attribute (e.g. thread) translation.
Fix it by adding a translation for that model's attribute (attributes.post.thread). The error message reveals the (wrongly) located I18n data (from attributes.thread)….
A common mistake in validations using regular expressions
You certainly use regular expressions for validating strings, e.g. e-mail addresses by saying
validate :email, :with => /.../
Such regular expressions often look something like the following: /^[\w+\-.]+@[a-z\d\-.]+\.[a-z]+$/i which perfectly matches as expected:
>> "foo.bar-ooops@bar.com".match /^[\w+\-.]+@[a-z\d\-.]+\.[a-z]+$/i
=> #<MatchData "foo.bar-ooops@bar.com">
… and does not match unwanted values:
?> "invalid email@invalid host.com".match /^[\w+\-.]+@[a-z\d\-.]+\.[a-z]+$/i
=> nil
I know that the express…
Write custom RSpec matchers
There are three ways to define your own RSpec matchers, with increasing complexibility and options:
1) Use RSpec::Matchers.define
RSpec::Matchers.define :be_a_multiple_of do |expected|
match do |actual|
actual % expected == 0
end
# optional
failure_message do |actual|
"expected that #{actual} would be a multiple of #{expected}"
end
# optional
failure_message_when_negated do |actual|
"expected that #{actual} would not be a multiple of #{expected}"
end
end
This is automat…
Gemika 0.4.0 released
We added support to read the include option from the travis.yml file. All combinations defined in the include option are added to the existing matrix. If no matrix exist, these are the only ones that are run.
This change should make it simpler to understand, which Ruby versions are actually run for a specific Gemfile.
Example with matrix
rvm:
- 2.1.8
- 2.3.1
gemfile:
- gemfiles/Gemfile1
- gemfiles/Gemfile2
matrix:
include:
- rvm: 2.6.3
gemfile: gemfiles/Gemfile3
This will run all these 5 combinations: …
Matching unicode characters in a Ruby (1.9+) regexp
On Ruby 1.9+, standard ruby character classes like \w, \d will only match 7-Bit ASCII characters:
"foo" =~ /\w+/ # matches "foo"
"füü" =~ /\w+/ # matches "f", ü is not 7-Bit ASCII
There is a collection of character classes that will match unicode characters. From the documentation:
-
/[[:alnum:]]/Alphabetic and numeric character -
/[[:alpha:]]/Alphabetic character -
/[[:blank:]]/Space or tab -
/[[:cntrl:]]/Control character -
/[[:digit:]]/Digit -
/[[:graph:]]/Non-blank character (excludes spaces, co…
RubyMine users: you should be using bookmarks
RubyMine allows bookmarking lines of code. This is super-helpful when working on a complex problem.
I've been using this feature for a few years now, and so should you! :)
Here are the default Linux/Windows keystrokes. See the documentation for other keybindings.
Add an anonymous bookmark
F11
A gray checkmark will be shown in the gutter on the left.
If you press F11 again on a bookmarked line, the bookmark will be removed.
Add a named bookmark ("mnemonic")
Ctrl …
When upgrading/downgrading RubyGems and Bundler on a server, you must clear bundled gems
On application servers, gems are usually bundled into the project directory, at a location shared across deployments.
This is usually shared/bundle inside your project's root directory, e.g. /var/www/your-project/shared/bundle/.
If you can't find that, take a look at current/.bundle/config and look for BUNDLE_PATH.
When you are changing the version of RubyGems or Bundler on a system where gems are installed this way, you must wipe that bundle directory in addition to the user and system gems or gems that are already ins…
Updated: Git: Revert one or more commits
Added instructions on how to revert multiple commits at once.
Ruby regular expression start/end line vs. start/end string
tl;dr: Most often you want to use \A and \z. Be careful when using ^ and $!
^ Start of line
$ End of line
!!("image/jpeg" =~ /^image\/(jpeg|png)$/) => true
!!("image/png" =~ /^image\/(jpeg|png)$/) => true
!!("application/javascript" =~ /^image\/(jpeg|png)$/) => false
!!("application/javascript\nimage/jpeg\nfoo" =~ /^image\/(jpeg|png)$/) => true
\A Start of string
\z End of string
```
!!("image/jpeg" =~ /\Aimage\/(jpeg|png)\z/) => true
!!("image/png" =~ /\Aimage\/(jpeg|png)\z/) => true
!!("application/javascript" =~ /\Aimage…
Be very careful with 301 redirects
Browsers support two kinds of redirects:
301 moved permanently302 moved temporarily
Be very careful with the 301 type. Most browsers seem to cache these redirects forever, unless you set different Cache-Control headers. If you don't have any cache control headers, you can never change them without forcing users to empty their cache.
The only fix is to keep redirecting the user to the correct page, so if you had
/page-1 --301--> /page-2
but you want
/page-1 --301-> /page-3
your only fix is to change it to
…
Ruby: How to use global variables for a conditional debugger
You can share a state in Ruby with global variables. Even if you should avoid them whenever possible, for debugging an application this could be temporary quite handy.
Example:
class User
after_save { byebug if $debug; nil }
def lock
self.locked = true
save
end
end
```
Rspec.describe User do
let(:user) { create(:user) }
before do
# Many users are created and saved in this hook, but we don't want the debugger to stop for them
end
…
Unpoly: Automatically show the full better_errors page when Rails raises an error
When an AJAX request raises an exception on the server, Rails will show a minimal error page with only basic information. Because all Unpoly updates work using AJAX requests, you won't get the more detailled better_errors page with the interactive REPL.
Below is an event listener that automatically repeats the request as a full-page load if your development error shows an error page. This means you get…
Use Time.current / Date.current / DateTime.current on projects that have a time zone
Basically, you now need to know if your project uses a "real" time zone or :local, and if config.active_record.time_zone_aware_attributes is set to false or not.
-
With time zones configured, always use
.currentforTime,Date, andDateTime.ActiveRecord attributes will be time-zoned, and
.currentvalues will be converted properly when written to the database.
Do not useTime.nowand friends. Timezone-less objects will not be converted properly when written to the database. -
With no/local time zone use
Time.now, `…
CSS: Don't target multiple vendor-prefixed pseudo-elements in a single rule
Some pseudo-elements need to be addressed with vendor prefixes. E.g. ::selection is not supported by Firefox, you need to use ::-moz-selection instead.
What you cannot do is to define a single CSS rule to address both the standard and vendor-prefixed form:
::selection, ::-moz-selection {
background-color: red;
}
This rule will be ignored by all browsers. The reason is that if a browser doe…
Project management best practices: Working with clients in person
When working on a bigger project, the easiest way to improve your work relation with a client or an external product manager, is to make sure you see them in person once in a while.
It makes sense to meet each other when you start working together to establish a relationship and find out what makes them tick.
If you need to discuss a larger package of work, use the opportunity and meet up and discuss it in person.
When you have to discuss something in your daily work, prefer talking to writing, and consider using a webcam.