There are different ways to define a lambda or proc in ruby:

1. with lambda-keyword

   test = lambda do |arg|
     puts arg
   end
   

2. with the lambda literal -> (since ruby 1.9.1)

   test = -> (arg) do
     puts arg
   end
   

3. with the proc keyword (which defines a lambda that does not test the given number of arguments):

   test = lambda do |arg|
     puts arg
   end
   

And there are different ways to call them:

1. call (we prefer this)

   ```
   test.call('hello world')
   ``…

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 …

If you want to make your Rails application be capable of sending SMTP emails, check out the action mailer configuration section in the Ruby on Rails guide.

TL;DR you will end up having an smtp_settings hash that looks something like this:

smtp_settings = {
  address: ...,
  domain: ...,
  port: ...,
  user_name: ...,
  password: ...,
  authentication: ...,
  tls: ...,
  enable_starttls_auto: ...,
}

This hash can be set as the `delivery_me…

Calling bundle update (without arguments) updates all your gems at once. Given that many gems don't care about stable APIs, this might break your application in a million ways.

To stay sane, update your gems using the applicable way below:

Projects in active development

Update the entire bundle regularily (e.g. once a week). This ensures that your libraries are up-to-date while it's easy to spot major version bumps which may break the app.

Projects that have not been updated in a while

1. [Update a single gem conservatively](htt…

In MySQL comparing zero to a string 0 = "any string" is always true!

So when you want to compare a string with a value of an integer column, you have to cast your integer value into a string like follows:

SELECT * from posts WHERE CAST(posts.comments_count AS CHAR) = '200' 

Of course this is usually not what you want to use for selecting your data as this might cause some expensive database operations. No indexes can be used and a full table scan will always be triggered.

If possible, cast the compared value in your application to…

Im using the terminator terminal with the keyboard shortcut Control+Shift+E for splitting the terminal. I got used to this shortcut.

Yesterday the Ubuntu update seems to have upgraded ibus, which got this emoji picker that also uses Control+Shift+E to open.
You can change this behaviour by opening the ibus setup from the console:

ibus-setup

A window will open and you can delete the shortcut in the emoji tab (Emoji => … => detele). You're no…

When you have string contents (e.g. a generated binary stream, or data from a remote source) that you want to store as a file using Carrierwave, here is a simple solution.

While you could write your string to a file and pass that file to Carrierwave, why even bother? You already have your string (or stream).
However, a plain StringIO object will not work for Carrierwave's ActiveRecord integration:

>> Attachment.create!(file: StringIO.new(contents))
TypeError: no implicit conversion of nil into String

This is because Carrierwave ex…

jQuery's deferred objects behave somewhat like standard promises, but not really.

One of many subtle differences is that there are two ways to chain callbacks to an async functions.

The first one is done, which only exists in jQuery:

$.ajax('/foo').done(function(html) {
  console.debug("The server responded with %s", html);
});

There is also then, which all promise libraries have:

```
$.ajax('/foo').then(function(html) {
console.debug("The server resp…

Detecting if a Javascript is running under Selenium WebDriver is super-painful. It's much easier to detect the current Rails environment instead.

You might be better of checking against the name of the current Rails environment. To do this, store the environment name in a data-environment of your <body>. E.g., in your application layout:

%body{'data-environment' => Rails.env}

Now you can say in a piece of Jav…

1. Install the latest bundler version:

   gem install bundler
   Fetching bundler-2.1.2.gem
   Successfully installed bundler-2.1.2
   1 gem installed
   

2. Update the bundler version in you Gemfile.lock:

   bundle _2.1.2_ update --bundler  
   

Note: Older Ruby and Rails can not use the latest bundler 2 version, so you need to stay on bundler 1.

1. Saving files to a directory that is not shared between deploys or servers

If you save your uploads to a made up directory like "RAILS_ROOT/uploads", this directory goes away after every deploy (since every release gets a new). Also this directory is not shared between multiple application servers, so your uploads are randomly saved to one local filesystem or another. Fixing this afterwards is a lot of fun.

Only two folders are, by default, shared between our application servers and deployments: "RAILS_ROOT/storage" and `"RAILS…