When using GROUP BY, MySQL now complains if the SELECT includes columns which are not part of the GROUP BY.

Reason:

There could be multiple values for those columns per group but only one value can be picked for the results.

The default behaviour of MySQL prior to version 5.7 will not complain and arbitrarily choose a value. But this leads to non-deterministic results. So MySQL now has enabled the only_full_group_by setting by default to prevent this.

In Rails this could lead to some trouble, because scopes do not have sp...

When a has_many association basically serves to store a list of associated strings (tags, categories, ...), it can be convenient to represent this association as a string array in the containing model. Here is an example for this pattern from the acts-as-taggable-on gem:

post = Post.last
p post.tag_list # ['foo', 'bar', 'baz']
post.tag_list = ['bam']
p post.tag_list # ['bam']

This string array tag_list is magical in several ways:

• It is read from and written to a `has...

• If Rails or Rake are complaining about a missing gem that is listed in your Gemfile.lock and the listed version is properly installed, something is seriously wrong and needs to be fixed.
• If you accidently executed bundle install some_gem although you wanted bundle update some_gem

What is wrong

Let's say your Gemfile asks for some-gem which you can see when running gem list but bundle show some-gem just gives you an error:

Could not find gem 'some-gem', in any of the sources

Another indicator: Doing a `...

To achieve this goal you have to setup the session store like the following example:

  MyApp::Application.config.session_store(
    :cookie_store,
    {
      :key => '_myapp_session',
      :domain => :all, # :all defaults to da tld length of 1, '.web' has length of 1
      :tld_length => 2 # Top Level Domain (tld) length -> '*.myapp.web' has a length of 2
    }
  )

The invconvenient side effect for local development

… or: Why do I get "Can't verify CSRF token authenticity" even if csrf token is present?

As `:domain => :all...

When you use the send_file method to send a local file to the browser, you can save resources on the application server by setting the :x_sendfile option to true. This option is activated by default for Rails 3, so you need to understand this.

What this option does is not to send any data at all, but rather set the local file path as a new response header:

X-Sendfile: /opt/www/awesome-project/shared/downloads/image.png

When the response comes back from Rails to...

I got this error after upgrading Ruby from 2.4.5 to 2.6.4 when I opened the Rails console - rails server still worked.

Running via Spring preloader in process 14679
Loading development environment (Rails 5.2.2.1)
Traceback (most recent call last):
.../lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:175:in 'fork': No such file to load -- irb/encoding_aliases.rb (LoadError)
.../lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:175:in 'fork': undefined method 'reject!' for nil:NilClass (NoMethodError)
.../li...

Geoffrey Grosenbach has created Gruff for easily plotting graphs. It is written in pure Ruby and integrates with Rails applications.

It provides features as automatic sizing of dots and lines (the more values, the thinner the graph's elements), custom or predefined themes, different styles (bar, line, dot and many more) and multiple graphs in one chart.

Installation

In your Gemfile:

gem 'rmagick', :require => false
gem 'gruff'

Then run bundle install (and don't forget to restart your development server.)

Usage

This i...

When you have a localized website, you may want to redirect users to their preferred language when they visit the root path.
Here is how to do it without a server-side component (like a Rails application).

• Use JavaScript's navigator.language (real browsers and IE11+) and navigator.userLanguage (old IEs).
• Use a <meta> refresh as fallback
• Provide buttons for paranoid users that disabled JavaScript and meta refreshs.

JavaScript

The following JavaScript will try to auto-detect a user's preferred language.

It understands string...

Establishing a new SSH connection usually takes only a few seconds, but if you’re connecting to a server multiple times in succession the overhead starts to add up. If you do a lot of Git pushing and pulling or frequently need to SSH to a dev server, you’ve probably felt the pain of waiting for SSH to connect so you can get back to doing work.

As we get ready to upgrade our servers I thought it’d be a good time to upgrade our deployment process. Currently pushing out a new version of GitHub takes upwards of 15 minutes. Ouch. My goal: one minute deploys (excluding server restart time).

The Juggernaut plugin for Ruby on Rails aims to revolutionize your Rails app by letting the server initiate a connection and push data to the client. In other words your app can have a real time connection to the server with the advantage of instant updates.

We recently decided our CI server needed an overhaul. I really enjoyed Integrity as a build server, but after trying out Hudson it’s hard to say I want to go back. Hudson has several huge advantages.

Precondition

• You are not using javascript tests
• The file is served from a public folder (not via controller)

Problem description

If you deliver files from a public folder it might be that the Content-Disposition header is not set. That's why the following spreewald step might raise an error:

Then I should get a download with filename "..."

expected: /filename="some.pdf"$/
     got: nil (using =~) (RSpec::Expectations::ExpectationNotMetError)

Solution

One solution...

For my Gem Session project Holly I ran the Ironman of drag'n'drop implementations:

• Dragging in nested lists
• User-definable order of items
• Complicated item elements with super-custom CSS and other Javascript functionality
• Items that can be both leaves and containers of other items
• has_ancestry on the server side

Things I learned:

• Be ready to write a lot of CSS. You need to indicate what is being dragged, where it will be dropped, if it is dropped above, below o...

When talking to your MySQL server via a mysql shell, you can terminate queries by ; or \G -- the latter gives you a vertical output.

You know this:

mysql> SELECT * FROM users;
+----+---------+---------------------+-----------------+
| id | name    | email               | greeting        |
+----+---------+---------------------+-----------------+
|  1 | Alice   | alice@example.com   | Hello world!    |
|  2 | Bob     | bob@example.com     | Hello universe! |
|  3 | Charlie | charlie@example.com | Hi mom!    ...

Given you store files on Amazon S3 and you need to stream those files out to people while you don't want them to be able to distribute the content simply by sharing the S3 URL.

You could either mark the bucket as private and fetch the appropriate files from S3 to your application server and stream them to the client finally. While this is possible, I'd recommend to use what AWS calls "Query String Authentication".

If you're using Paperclip you can chose between two sto...

If you need to enable NewRelic monitoring on certain machines within the same Rails environment, a simple solution is to utilize the respective hostnames of you machines.

For example, if you have 8 application servers (e.g. app1.example.com, app2.example.com, ...) and want to enable NewRelic on app1 and app2 only, utilize those steps to do so:

1. Put the attached file into your config directory (config/custom_new_relic_configuration.rb).
2. Specify on which hosts NewRelic should be enabled (see NEWRELIC_HOSTS constant and list ...

So you have a restangular collection and you want to remove an element from it, after you've successfully deleted it from the server.

The README suggests to say something like $scope.users = _.without($scope.users, user). While that works at first glance (the element is no longer in your collection), it will break horribly when you want to use restangular's attributes on that collection.

This...

Here is a good explanation for zombie processes.

Quote:

If you have zombie processes it means those zombies have not been waited for by their parent (look at PPID displayed by ps -l). 
You have three choices: Fix the parent process (make it wait); kill the parent; or live with it.
Remember that living with it is not so hard because zombies take up little more than one extra line in the output of ps.

On a server I want to get informed if there are zombie processes and track them wi...

When using Savon to connect a SOAP API, you may want to use Savon::SpecHelper to mock requests in your tests as described in their documentation.

When sending a message body, the savon mock object requires a message to be set, like this:

savon.expects(:action_name).with(message: { user_id: 123 }).returns('<some xml>')

If you want to stub only the returned XML and do not care about request arguments, you can not omit with as Savon's helper will complain:

savo...

This note describes how to setup a box running Ubuntu to share its Internet connection with another PC.

• You will need two network interfaces to do this. One will connect to the Internet (e.g. UMTS card), one will share the connection with the other PC (e.g. Wired LAN).
• On the Ubuntu PC, right-click on the connection symbol in the tray. Select Edit connections.
• Switch to the wired LAN card. Go to Edit and set the method to Shared to other computers.
• Connect the other PC to your wired LAN card. You can use the same cable that wo...

If another session is accessing your database you are trying to reset or drop you might have seen the following error:

PG::ObjectInUse: ERROR:  database "foo_development" is being accessed by other users
DETAIL:  There is 1 other session using the database.

This could be the rails server, rubymine and many more. Beside terminating the session connection manually you can also find out the pid and kill the process.

1. rails db
2. SELECT * FROM pg_stat_activity;

datid            | 98359
datname          | foo_developm...

Apache HTTP server benchmarking tool (ab) is a nice tool to test performance on sites delivered by HTTP. If the site you're about to test is placed behind a login, follow these steps to successfully use ab on it.

1. Open the site to test in the browser of your choice. Do not login yet.
2. Use developer tools to show all cookies used by the site. (Chrome: Ctrl+Shift+i, open the 'Resources' tab and click on the site below 'Cookies' on the left. Firefox: Right-click on the site, open 'We...