Take care when trying to set attributes to nil in a blueprint.

Given the following master blueprint:
Story.blueprint do
title
author { User.make }
editor { User.make }
end

This approach will not overwrite/remove the editor defined in the master blueprint:
Story.blueprint(:draft) do
editor nil
end

...whereas this one will (note the lambda):
Story.blueprint(:draft) do
editor { nil }
end

If you get an ActiveRecord::RecordNotSaved error, a method inside one of your model's callback chains (before_save etc) possibly returned false.

This commonly happens when you have a method setting attributes and the last one is a boolean set to false (as the value of the last statement is returned). Fix this by simply calling true at the end of such methods:

def hide
  self.visible = false
  true
end

Note that nil won't cause this behavior. Thus, you can use an if without problems -- if you are not returning fal...

Lately, we’ve been exploring ways to offer web apps that perform like native apps on mobile devices. For this short sprint we targeted mobile WebKit browsers—especially the default browsers on iOS and Android—because of their widespread use and excellent support for HTML5 and CSS3. Here are a few things we’ve learned along the way.

Sometimes the order in which strings appear on a page matters to you.

Spreewald gives you steps like these:

Then I should see in this order:
  | Alpha Group |
  | Augsburg    |
  | Berlin      |
  | Beta Group  |

Or, if you prefer multiline strings:

Then I should see in this order:
  """
  Alpha Group
  Augsburg
  Berlin
  Beta Group
  """

The step ignores all HTML tags and only tests on plain text.

When you do tags with acts-as-taggable-on and want to preload associated tags, you can do so with

TaggedModel.scoped(:include => :tag)

Note however that this will only prevent tagged_model.tags from hitting the database. Using tagged_model.tag_list does not use the preloaded association.

Did you use the :select option in a find, and forgot to include foo?

SSL in Rails 3 is non-obvious.

Note: We are talking about Machinist 1 here, Machinist 2 may have solved this or might require a different approach.

Machinist allows named blueprints (e.g. User.blueprint(:admin)) that inherit from the master blueprint (User.blueprint).

If you also want to inherit from another blueprint (e.g. if "vip" should load "premium" and the master blueprint) you can do this:
User.blueprint(:vip) do
# Fields for the vip blueprint go her...

A popular ruby idiom I keep stumbling upon is
def do_some_thing_for(values)
values = Array(values)
values.each { ... }
end

The intent is to allow the user to pass in arrays as well as scalar values, since
Array("foo") == ["foo"]
Array(["foo", "bar"]) == ["foo", "bar"]

But Array() actually calls to_a on its arguments, which may not always do what you expect. For example
Array("foo \n bar") == ["foo \n", "bar"]

When Paperclip attachments should only be downloadable for selected users, there are three ways to go.
The same applies to files in Carrierwave.

1. Deliver attachments through Rails

The first way is to store Paperclip attachments not in the default public/system, but in a private path like storage inside the current release. You should prefer this method when dealing with sensitive data.

Make ...

You need to install the following packages before you can build the Nokogiri gem:

sudo apt-get install libxml2-dev libxslt1-dev

If you get an error message like that you are missing the Aspell files a specific language:

No word lists can be found for the language "de"

Solve it by installing the proper package, e.g. on Ubuntu:

sudo apt-get install aspell-de

If you have problems with SSH session timing out, add the following to your /etc/.ssh/config:

Host *
  ServerAliveInterval 55
  ServerAliveCountMax 2

Capybara's has_css? matcher has a couple of options you might find useful.

Check that a selector appears a given number of times

Use the :count option like this:

Then /^I should see (\d+) users?$/ do |count|
  page.should have_css('ul#users li', :count => count.to_i)
end

Check that a selector has a given text content

Use the :text option like this:

Then /^I should see a user with name "([^\"]*)"$/ do |nam...

Hooks lets you define hooks declaratively in your ruby class. You can add callbacks to your hook, which will be run as soon as you run the hook.

Even when you're using bundler, it might be significant in which order your gems are listed in your Gemfile. This can happen when gems are running around calling require or require_dependency on other gems or application classes when loaded (don't do that!).

A known culprit of this is the (otherwise wonderful) resource_controller gem, which requires ApplicationController when loaded. When your ApplicationController requires later-loaded gems when loaded, Rails will not boot.

He...

This post will describe how I stumbled upon a code path in the Linux kernel which allows external programs to be launched when a core dump is about to happen. I provide a link to a short and ugly Ruby script which captures a faulting process, runs gdb to get a backtrace (and other information), captures the core dump, and then generates a notification email.

It can be useful to have a Ruby expression like condition ? positive_case : negative_case in MySQL queries:

UPDATE users SET monthly_debit = IF(subscriber, 19, 0)

1. [ ] [ ]=
2. **
3. ! ~ + -
4. * / %
5. + -
6. >> <<
7. &
8. ^ |
9. <= < > >=
10. <=> == === != =~ !~
11. &&
12. ||
13. .. ...
14. ? :
15. = %= { /= -= += |= &= >>= <<= *= &&= ||= **=
16. defined?
17. not
18. or and
19. if unless while until
20. begin/end

For more information see Table 18.4 in The Pragmatic Programmer's Guide.

A good tool to generate strong passwords and secrets is "apg". You can get it with

sudo apt-get install apg

To create a strong secret for sessions, hashed Paperclip paths, etc. say

apg -m128 -a1 -E\'\"

Arguments explained:

• The -m parameter defines the secret length
• -a1 makes apg choose from all 7-bit ASCII characters instead of just the alphabet
• -E\'\" excludes quote characters so you can easily paste the secret into a Ru...

Inside before :each blocks you can refer to variables that you introduce via let later on.

They do not need to be defined ahead of your before block and can be different for individual sections.

It works just like that:

describe User do
  describe '#locked?' do
    
    before :each do
      subject.should_receive(:current_plan).and_return plan
    end
    
    context 'when expiring today' do
      let(:plan) { stub(:expiry => Date.today) }
      it 'should be false' do
        subject....

Ruby gem that provides an AR-style interface for the Pivotal Tracker API.

You need to install the following packages before you can build the Paperclip gem:

sudo apt-get install imagemagick librmagick-ruby

If you have several submit elements (inputs or buttons with type="submit") that each cause different things to happen (e.g. you might have a button that sends an extra attribute) you might run into trouble when submitting the form by pressing the return key in a field.

When nothing fancy like a tabindex is defined it seems as if the first submit element inside a form is chosen (and has its attributes submitted) when pressing return.\
So, if possible, put your "default" (aka least harmful) submit element before others.

NB: If you s...