This card compares patterns to store trees in a relation database like MySQL or PostgreSQL. Implementation examples are for the...

When you load a dump for development, records may reference images that are not available on your machine.

The maximum version of Internet Explorer you can have depends on your version of Windows. E.g. Windows 7 users can...

This is a visualization of the files that will be generated by some useful rails generators. Invoke a generator from...

on the bash (issued as postgres user) Start/Stop/Restart PostgreSQL pg_ctl -D $configdir start|stop|restart Start/Stop/Restart the corresponding PostgreSQL...

Looks like ActiveState is trying to market a new Ruby distribution for Enterprises: ActiveRuby Enterprise Edition is designed for businesses...

Occasionally, you have to talk to APIs via HTTPS that use a custom certificate or a misconfigured certificate chain (like...

/home/.../ruby/gems/2.1.0/gems/bundler-1.14.3/lib/bundler/rubygems_ext.rb:45:in `full_gem_path': uninitialized constant Bundler::Plugin::API::Source (NameError) Solution: Upgrade Rubygems beyond 2.6.9...

Adding a gem means you take over the liability towards the external code. Checklist Based on "To gem, or not...

We generally use multiple application servers (at least two) and you have to search on all of them if you...

We have projects that have been developed using many different versions of Ruby. Since we do not want to...

If you have a replication error with MySQL and you know the "error" is okay (e.g. you've executed the...

The rack-contrib gem brings a JSONP middleware that just works™. Whenever a JSON request has a callback parameter, it...

TruffleRuby is an experimental Ruby implementation that tries to achieve ~10x performance over MRI. This has been on our radar...

Sometimes huge refactorings or refactoring of core concepts of your application are necessary for being able to meet new requirements...

Exercise 1: XML On the start page of your Movie DB, show the title of a random movie that is...

Adopting legacy Rails apps Talk to your mentor about how we're approaching applications that are either old or abandoned...

So you're getting an error like this: undefined method `activate_bin_path' for Gem:Module (NoMethodError)

If your Carrierwave uploader dynamically generates the filename (e.g. by incorporating a user's name), you must call model.save! after...

TL;DR: Update the 'net-ssh' gem by adding to your Gemfile: gem 'net-ssh', '=2.9.1' Now run bundle update...

Put the following into config.ru in your Rails root folder: # Require your environment file to bootstrap Rails require ::File.dirname(__FILE...

Building plain text emails with an .erb template doesn't allow you to indent code like you normally do in...

This card tries to summarize by example the different uses of heredoc. In Ruby << vs. <<- vs. <<~ In Rails strip_heredoc...