When you need to use diff in either some Ruby code or your Rails app, use the differ gem.

puts Differ.diff "foo", "boo"
# => {"boo" >> "foo"}

Usage

There are several variants available, all using the base method diff(to, from, separator = "\n").
You have diff_by_line, diff_by_word, diff_by_char and may of course use your own separator:

puts Differ.diff 'Hauptsatz, und mein Nebensatz.', 'Hauptsatz, und dein Nebensatz.', ','
# => Hauptsatz,{" und dein Nebensatz." >> " un...

Tool to show you which gems are slow to load:

➜  git:(master) ✗ bundle exec bumbler
[#################################################                             ]
(49/65) travis-lint...
Slow requires:
    110.21  render_anywhere
    147.33  nokogiri
    173.83  haml
    179.62  sass-rails
    205.04  delayed_job_active_record
    286.76  rails
    289.36  mail
    291.98  capistrano
    326.05  delayed_job
    414.27  pry
    852.13  salesforce_bulk_api

A rough guide how to implement a REST API.

The discussion here includes some interesting points as well:

• Timestamps: ISO8601 format ("2021-02-22T20:34:53.686Z")
• Google API guideline: https://google.aip.dev/
• Numbers: String vs. Number

  The JSON number type is not a double. It's just a number of arbitrary size and precision in integer/decimal/E format that can be parsed as whatever the parser finds fitting.

• Pagination: Limit + Offset vs. Object ID / Pointer vs. System-Version...

• Now supports RSpec 3 and Rails 4
• Drops support for state_machine, which has some issues with Rails 4 and isn't actively maintained

Using .downcase or .upcase on strings containing umlauts does not work as expected in Ruby versions before 2.4. It leaves the umlauts unchanged:

"Über".downcase
=> "Über"

"Ärger".downcase
=> "Ärger"

The very same applies for french accents (Thanks Guillaume!):

"Être ou ne pas être, telle est la question".downcase
=> "Être ou ne pas être, telle est la question"

Obviously, this leads to problems when comparing strings:

"Über".downcase == "über"
=> false

In Rails you can use ActiveSupports' [multib...

MySQL and MariaDB have an SQL mode setting which changes how MySQL behaves.

The SQL mode value is comprised of multiple flags like "STRICT_TRANS_TABLES, NO_ZERO_IN_DATE". Each flag activates or disables a particular behavior.

The default SQL mode varies widly between versions of MySQL and MariaDB. In general, more recent versions of MySQL and MariaDB have stricter settings than older versions, and MySQL has stricter settings than the more liberal MariaDB.

If your app explodes ...

PostgreSQL and ActiveRecord have a good support for storing dynamic attributes (hashes) in columns of type JSONB. But sometimes you are missing some kind of validation or lookup possibility (with plain attributes you can use Active Record's built-in validations and have your schema.rb).

One approach about being more strict with dynamic attributes is to use JSON Schema validations. Here is an example, where a project has the dynamic attributes analytic_stats, that we can use to store analytics from an external measurement tool.

• A g...

If you're using the webdrivers gem and VCR together, depending on your configuration, VCR will yell at you regulary.
The webdrivers gem tries to update your webdrivers on your local machine. To do so, it checks the internet for newer versions, firing an HTTP-request to e.g. https://chromedriver.storage.googleapis.com

You can "fix" this in multiple ways:

1. Update your drivers on your machine with
   RAILS_ENV=test rake webdrivers:chromedriver:update

2. Ignore the driver update-URL in your ...

We often use VCR to stub external APIs. Unfortunately VCR can have problems matching requests to recorded cassettes, and these issues are often hard to debug.

VCR's error messages mostly look like this and are not very helpful:

An HTTP request has been made that VCR does not know how to handle:
         POST http://another-site.de:9605/json/index

VCR fails if the request does not exactly look like the request it has recorded. If the request is d...

When searching for text in a MySQL table, you have two choices:

• The LIKE operator
• FULLTEXT indexes (which currently only work on MyISAM tables, but will one day work on InnoDB tables. The workaround right now is to extract your search text to a separate MyISAM table, so your main table can remain InnoDB.)

I always wondered how those two methods would scale as the number of records incr...

The way Rational#to_s works on Ruby has changed from Ruby 1.9 on. Here is how to get the old behavior back.

You may want this for things where Rationals are being used, like when subtracting Date objects from one another.

What's happening?

Converting a Rational to a String usually does something like this:

1.8.7 > Rational(2, 3).to_s
=> "2/3"
1.9.3 > Rational(2, 3).to_s
=> "2/3"
2.0.0 > Rational(2, 3).to_s
=> "2/3"

However, when you have a Rational that simplifies to an integer, you will only get a St...

If you need to capture signatures on an IPad or similar device, you can use Thomas J Bradley's excellent Signature Pad plugin for jQuery.

To implement, just follow the steps on the Github page.

The form

If you have a model Signature with name: string, signature: text, you can use it with regular rails form like this:

- form_for @signature, :html => { :class => 'signature_form' } do |form|
  %dl
    %dt
      = form...

When you do something like this in your code:

def var_value
  @var ||= some_expensive_calculation
end

Be aware that it will run some_expensive_calculation every time you call var_value if some_expensive_calculation returns nil.

This illustrates the problem:

def some_expensive_calculation
  puts "i am off shopping bits!"
  @some_expensive_calculations_result
end

When you set @some_expensive_calculations_result to nil, ||= runs some_expensive_calculation every time....

In Ruby on Rails, all objects have a useful blank? method. It returns true for nil but also for empty strings or empty arrays. There is also a universal method present? which returns true for all values that are not blank?.

In JavaScript you need to roll your own implementation of blank? and present?.

If your application uses [Unpoly](...

When you have objects in your database that hold latitude and longitude and you want to find others that are close to given coordinates you can use the Graticule gem.

Graticule

Graticule offers several methods to compute the distance between two geo-dated objects but fetching records from the database that are within a given radius of a location is a bit trickier:

def close_destinations(latitude, longitude)
  distance_sql = Graticule::Distance::Spherical.to_sql(:latitude => l...

You can define methods using def or define_method. In the real world, there is no performance difference.

define_method is most often used in metaprogramming, like so:

define_method :"#{attribute_name}_for_realsies?" do
  do_things
end

Methods defined via define_method are usually believed to have worse performance than those defined via def.
Hence, developers sometimes prefer using class_eval to define methods using def, like this:

class_eval "def #{attribute_name}_for_realsies?; do_things; end"

You can be...

UI sortable helps reordering items with drag 'n drop. It works quite fine.

Proven configuration for sorting table rows

When invoking the plugin, you may pass several options. This set is working fine with table rows:

$tbody.sortable # Invoke on TBODY when ordering tables
  axis: 'y' # Restrict drag direction to "vertically"
  cancel: 'tr:first-child:last-child, input' # Disable sorting a single tr to prevent jumpy table headers
  containment: 'parent' # Only drag within this container
  placehol...

To upload a file via AJAX (e.g. from an <input type='file'>) you need to wrap your params in a FormData object.

You can initialize a FormData using the contents of a form:

var form = document.querySelector('form.my-form') // Find the <form> element
var formData = new FormData(form); // Wrap form contents

Or you can construct it manually, param by param:

var fileInput = document.querySelector('form input[type=file]');
var attachment = fileInput.files[0];

var f...

We recently decided to put static content for HouseTrip.com to Amazon Cloudfront for a faster user experience. This happens fully automatically on deploy and is transparent in development. Together with a heavy use of sprites this sped up page load time quite nicely.

These are a couple of the problems you need to solve in order to do this:

• There is no good way to invalidate Cloudfront cached assets, and Cloudfront will ignor...

The Ace editor is a great enhancement when you want users to supply some kind of code (HTML, JavaScript, Ruby, etc).
It offers syntax highlighting and some neat features like auto-indenting.

For Webpack 3+

Integrate as described in the documentation. For example load ace Editor like this:

  function loadAceEditor() {
    return import(/* webpackChunkName: "ace" */ 'ace-builds/src-noconflict/ace').then(() => {
      return import(/* webpackChunkName: "ace" */ 'ace-builds/webpack-r...

Our old solution for cronjobs, the "craken" plugin, is no longer maintained and does not work on Rails 3.2+.

We will instead use the whenever gem.

"Whenever" works just like "craken", by putting your rake tasks into the server's cron table. Everything seems to work just like we need it.

Installation for new projects

1. Add "whenever" to your Gemfile:

    group :deploy do
      gem 'whenever', require: false
    end
   

2. Add it to your config/deploy.rb:
   ...