When you work with a Rails 3.1+ application, you will be working with the asset pipeline. The asset pipeline is awesome until you deploy. Then it will be less so if you haven't done everything as the pipeline expected it from you.

The problem

When using the asset pipeline your assets (images, javascripts, stylesheets, fonts) live in folders inside app:

app/assets/fonts
app/assets/images
app/assets/javascripts
app/assets/stylesheets

With the asset p…

For outputting a given String in HTML, you mostly want to replace line breaks with <br> or <p> tags.
You can use simple_format, but it has side effects like keeping some HTML.

If you only care about line breaks, you might be better off using a small, specialized helper method:

def format_linebreaks(text)
  safe_text = h(text)
  paragraphs = split_paragraphs(safe_text).map(&:html_safe)

  html = ''.html_safe
  paragraphs.each do |paragraph|
    html << content_tag(:p, paragraph)
  end    ...

Redirect responses to PATCH and DELETE requests will be followed with PATCH or DELETE. Redirect responses to GET and POST will be followed with a GET.
The Rails form_for helper will use a workaround to send POST requests with a _method param to avoid this issue for PATCH/DELETE.

If you make requests yourself, watch out for the following behavior.

When you make an AJAX request PATCH /foo and the /foo action redirects to /bar, browsers will request PATCH /bar. You probably expected the second request to be…

simple_format ignores Rails' XSS protection. Even when called with an unsafe string, HTML characters will not be escaped or stripped!

Instead simple_format has a whitelist of tags it allows. These are:

ActionView::Base.sanitized_allowed_tags
=> #<Set: {"small", "dfn", "sup", "sub", "pre", "blockquote", "ins", "ul", "var", "samp", "del", "h6", "h5", "h4", "h3", "h2", "h1", "span", "br", "hr", "em", "address", "img", "kbd", "tt", "a", "acronym", "ab...

Working with lists in Javascript is painful because the native Array class is so poorly designed.

One way to reduce the pain is to to use Underscore.js's functions like _.each, _.map or _.select, which unfortunately clutters your code with awkward calls to the _ helper.

Fortunately when you use CoffeeScript you don't need any of that. CoffeeScript has a very versatile for keyword that can do anything that each, collect or select can do. Enjoy!

each

```
f…

Simply add this to your .rspec instead:

--require spec_helper

If you are on rspec >= 3 and use a rails_helper.rb require this instead of the spec_helper:

--require rails_helper

If you are using parallel_tests and this is not working for you, .rspec might be ignored. Try using a .rspec_parallel file.

To return non-HTML responses (like XLS spreadsheets), we usually use the

respond_to do |format|
  format.xls do
    # send spreadsheet
  end
end

This is often, but not always the same as checking for params[:format] == :xls, so don't rely on this when e.g. one format checks for authorization and the other doesn't.

params[:format] is only set when a user explicitly puts a .xls at the end of the URL.

The format.xls block also responds when the user's browser requests the application/excel MIME type.

If Intern…

Lets say we have a user with a contract whereas contract is a mounted carrierwave file.

Now we want to send the link to the contract in a mail. For this use case join the root_url with the public contract path in the mailer view:

Plain text email

URI.join(root_url, @user.contract.url)

HTML email

link_to('Show contract', URI.join(root_url, @user.contract.url).to_s)

Note: You need to follow [http://guides.rubyonrails.org/action_mailer_basics.html#g…

Our preferred way of testing ActiveRecord is to simply create/update/destroy the record and then check if the expected behavior has happened.

We used to bend over backwards to avoid touching the database for this. For this we used a lot of stubbing and tricks like it_should_run_callbacks.

Today we would rather make a few database queries than have a fragile test full of stubs.

Example

Let's say your User model creates a first Project on cr…

When your Cucumber feature needs to browse the page HTML, and you are not sure how to express your query as a clever CSS or XPath expression, there is another way: You can use all and find to grep through the DOM and then perform your search in plain Ruby.

Here is an example for this technique:

Then /^I should see an image with the filename...

Form fields can be rendered as noneditable by setting the disabled or the readonly attribute. Be aware of the differences:

disabled fields

• don’t post to the server
• don’t get focus
• are skipped while tab navigation
• available for button, fieldset, input, select, textarea, command, keygen, optgroup, option

Browser specific behavior:

• IE 11: text inputs that are descendants of a disabled fieldset appear disabled but the user can still interact with them
• Firefox: selecting text in a disabled text field is no…

Partials always define a local variable with the same name as themselves. E.g. when you are in _recent_users.html.erb, a local variable recent_users will be defined and overshadow any helper method that is also called recent_users().

If you would like to use a helper method recent_users() in a partial _recent_users.html.erb you can say this in the partial template:

<% recent_users = self.recent_users() %>
<% recent_users.each do |user| %>
  ...
<% end %>

If you want to make a screenshot of a website that works well in print or on a high-DPI screen (like Apple Retina displays), here is how you can capture a high-resolution screenshot.

You can do this without an addon:

• Open the website
• If you have multiple monitoros:
  • Resize the Chrome window so it covers multiple monitors (in Linux you can hold ALT and resize by dragging with the right mouse button)
  • Zoom into the page using CTRL + and CTRL - so it covers most of the window area. Leave generous padding on the left and right so…