Normally you can list all gems of the current ruby version with gem list, which also includes the gems of you Gemfile. These can be uninstalled with gem uninstall gemname.

List and uninstall a gem installed via Bundler from Github

This does not work for gems installed directly from Github. They do not appear in gem list.

Show all gems installed via Github by bundler:

ls ~/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/bundler/

Remove a gem installed via Github by Bundler:

```
rm -rf ~/.rbenv/versions/2.4.1/lib/ruby/gems/2….

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

DON'T

<%= 'foo' if bar %>

"\n" if bar is false

"foo\n" if bar is true

<%= nil %>

"\n"

<% if true %>
  <%= 'foo' %>
<% end %>  

" foo"

<%= 'foo' %>

<%= 'bar' %>

"foo\n\nbar\n"

DO

Write unindented code to get the expected result.

<% if bar %>
<%= 'bar' %>
<% end %>
<%= 'foo' %>
<%= 'bar' %> 

• Use [Form Models](https://github.com/makandra…

A check if two date or time ranges A and B overlap needs to cover a lot of cases:

1. A partially overlaps B

2. A surrounds B

3. B surrounds A

4. A occurs entirely after B

5. B occurs entirely after A

This means you actually have to check that:

• neither does A occur entirely after B (meaning A.start > B.end)
• nor does B occur entirely after A (meaning B.start > A.end)

Flipping this, A and B overlap iff A.start <= B.end && B.start <= A.end

The code below shows how to implement this in Ruby on Rails. The example is a clas…

Just found out about a great feature in Rails that seems to be around since Rails 2. Start a console with the --sandbox (or -s) parameter:

rails console --sandbox

All changes you make to the database will be rolled back on exit.

Note however, that changes beyond the database (deleting files, sending emails, etc) cannot be rolled back!

There seems to be no built-in matcher in RSpec to check if a string contains terms in the desired order. A simple workaround is to use a regular expression that also matches newlines (m-modifier).

Cons:

• The readability when terms need to be escaped is bad
• A failed spec has an error which needs manually action to be understood (Search if terms appear and in which order)

Example:

expect(ActionMailer::Base.last.to_s).to match(/Dear customer.*Account canceled.*You Awesome Company/m)

When you def methods in RSpec tests, you can use super to call a method definition that was created in a surrounding describe/context block.

Example:

describe User do

  def build_user(attributes = {})
    User.new(attributes)
  end

  describe '#my_method' do
    it 'does something' do
      # ...
    end

    context 'when the user has an e-mail address' do
      def build_user(attributes = {})
        super({ email: 'user@example.com' }.merge(attributes))
      end

      it 'd...

In this example we assume that not only the storage gem changes but also the file structure on disc.

A general approach

Part A: Create a commit which includes a script that allows you to copy the existing file to the new file structure.

Part B: Create a commit which removes all paperclip logic and replace it with the same code you used in the first commit

Part A

Here are some implementation details you might want to reuse:

• Use the existing models to read the files from
• Use your own carrierwave models to write t…

TL;DR Debugging problems with javascript errors in cucumber tests is sometimes easier in the browser. Run the test, stop at the problematic point (with Then pause from Spreewald 1.7+) and open VNC for Firefox.

Features:

• It does not freeze your server like when you're using a debugger. (Compared to the Then debugger step)
• It enables interacting with the server. (Compared to taking screenshots in Capybara)
• It is a faster altern…

Back in the war, Rails developers had to manually HTML-escape user-supplied text before it was rendered in a view. If only a single piece of user-supplied text was rendered without prior escaping, it enabled XSS attacks like injecting a <script> tag into the view of another user.

Because this practice was so error-prone, the rails_xss plugin was developed and later integrated into Rails 3. rails_xss follows a different approach: Instead of relying…

Background

Cross-Site Request Forgery (CSRF) is an attack pattern for websites. A CSRF attack is usually relevant in a browser context, where state is kept for multiple domains (as opposed to independent requests made e.g. with curl). The most common example is authentication via cookies. If a script on https://example.com made requests to https://docs.google.com, the browser would send all cookies for docs.google.com along, effectively given the script access to anythin…

This card describes how to pass an array with multiple element to a JavaScript function, so that the first array element becomes the first function argument, the second element becomes the second argument, etc.

Note how this is different from passing the entire array as the first argument. Compare these two different ways of calling fun() in Ruby:

# Ruby
array = [1, 2, 3]
fun(array)  # same as fun([1, 2, 3]) (1 argument)
fun(*array) # same as fun(1, 2, 3)   (3 arguments)

Depending on your culture the spreading of array e…

PostgreSQL, unlike MySQL, treats strings as case sensitive in all circumstances.

This includes

• comparison with = and LIKE
• collision detection in unique indexes

Usually this is fine, but some strings (like emails and usernames) should typically be treated as case insensitive.

There are a few workarounds available:

• use the citext extension
• use ILIKE instead of LIKE
• use Postgres' lower() function
• add an index on lower(email)

Probably the best approach is…