When using state_machine you sometimes need to know whether an object may execute a certain transition. Let's take an arbitrary object such as a blog article as an example that has those states:

A -> B -> C -> D

Additionally, you have transitions between the states as shown above. Let's call the transition between 'A' and 'B' transition_ab for simplicity. \
Given an object in state 'A'. You can call object.transition_ab but calling object.transition_bc! will obviously fail because ...

In order to prevent the browser from asking whether to remember the password, give a form an autocomplete attribute with the value off:

<form "/session" method="post" autocomplete="off">
  ...
</form>

Rails example

form_for @model, :html => { :autocomplete => "off" } do |form|

This is easy:

require 'open-uri'

File.open('/target/path/to/downloaded.file', "wb") do |file|
  file.write open('http://example.com/your.file').read
end

Basic Authentication

When your file is protected by HTTP Basic Authentication, pass your credentials as hash:

File.open('/target/path/to/downloaded.file', "wb") do |file|
  file.write open('http://example.com/your.file', :http_basic_authentication => [your_username, your_password]).read
end

After starting the Rails server in a freshly generated Rails 3.1 project you could see an error message such as

/usr/lib/ruby/gems/1.8/gems/execjs-1.3.0/lib/execjs/runtimes.rb:50:in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)

Just add a JavaScript runtime to your Gemfile and the error vanishes.

Examples:

gem 'therubyracer'
gem 'extjs'

Note: This applies specifically to MySQL. In PostgreSQL for example, this is not an issue.

If you care about performance, never use a query like

UPDATE users SET has_message = 1 WHERE users.id IN (SELECT user_id FROM messages)

MySQL does not optimize this and seems to scan the temporary table, which isn't indexed, for every row in the update statement. This applies to other statements than UPDATE as well.

Instead, either use a JOIN like

UPDATE users INNER JOIN messages ON messages.user_id = users.id SET has_message =...

Look here for informations how you can show the MySQL default character set.

At first you need the Amazon RDS Command Line Toolkit

• download and unzip the [Amazon RDS Command Line Toolkit](http://aws.amazon.com/developertools/A...

By default, Rails views escape HTML in any strings you insert. If you want to insert HTML verbatim, you need to call #html_safe. However, #html_safe does not "unescape" a string. It merely marks a string as safe for unescaped insertion.

How html_safe works

Calling html_safe on a String returns a new object that looks and acts like a String, but actually is a ActiveSupport::SafeBuffer:

"foo".length
# => 3
"foo".class
# => String

"foo".html_safe.length
# => 3
"foo".html_safe.class
# => ActiveSupport::S...

If you encounter the error message above when running cucumber, just execute...
rm rerun.txt
...in the Rails directory.

Or run...
tests
...from the geordi gem. This will do the work for you automatically.

RSpec 1 (Rails 2)

With the most recent spec_candy.rb helpers you can say:

User.stub_any_instance(:foo => :bar)
user = User.new
user.foo
# => :bar

RSpec 2 (Rails 3)

RSpec 2 comes with this feature built in:

User.any_instance.stub(:foo => :bar)
user = User.new
user.foo
# => :bar

RSpec 3
-------...

To show the collation of your tables you have to login to the MySQL console and execute SHOW TABLE STATUS FROM database;

mysql> SHOW TABLE STATUS FROM test;
+-------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+
| Name        | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_leng...

To show the MySQL default character set you have to login to the MySQL console and execute SHOW VARIABLES LIKE 'char%';

mysql> SHOW VARIABLES LIKE  'char%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | latin1                     |
| character_set_connection | latin1                     |
| character_set_database   | latin1                     |
| chara...

You can convert git commits into patch files. Those can be used to apply to a different repository [1] or by someone else (e.g. sent when sent to them via e-mail).

Creating a patch in git

1. Make your changes and commit them.
2. Run git format-patch COMMIT_REFERENCE to convert all commits since the referenced commit (not including it) into patch files.

For example, let's say you prepared 2 commits. Run:

git format-patch HEAD~~ 

This will create 2 files, one for each commit since HEAD~~, like these:

00...

First keep in mind that :dependent => :destroy hooks into before_destroy.
So when you use other before_destroy callbacks the sequential arrangement of your code may be important.

For example:

class Container < ActiveRecord::Base
  before_destroy :a_callback
  has_many :items, :dependent => :destroy
end

results in

container.destroy
# => a_callback
# => container.items.destroy_all

but

class Container < ActiveRecord::Base
  has_many :items, :dependent => :destroy
  before_...

Using the jQuery adapter breaks the built-in save function of CKEditor.

Phenomenon: The page is submitted correctly, but the original values of the form fields were posted instead of what was typed in the editors.

Work around: Basicly instead of initiating the editor using the above example I ended up using the following:

$( 'textarea.editor').each( function() {

    CKEDITOR.replace( $(this).attr('id') );

});

Note: This assumes that each field using the editor has its own unique ID.

The Rails logger will store its content in a buffer and write it into the file system every 1000 lines. This will come back to bite you when using Rails.logger.info to write log output during Rake tasks or on a production console.

You often won't notice this because for the development and test environments auto_flushing is set to write after each line. On production environments the Rails logger writes only every 1000 lines -- and not upon shell or script ter...

RSpec lets you define the arguments with which you expect a method to be invoked:

subject.should_receive(:say).with('hello')

Sometimes you don't care about the exact arguments. For such cases RSpec comes with argument constraints like anything or hash_including:

subject.should_receive(:update_attributes).with(hash_including(:message => 'hi world'))

You can go even further and use any R...

Calling #gsub on a string that was previously marked as #html_safe will lead to unexpected behavior. E. g. backreferences to captured groups ($1, $2) will be nil even if the group was matched.

There is no universal workaround available since you can't expect #html_safe strings to still be safe after using gsub on them.

You can, however, fix the $1 gsub behavior on html_safe strings.

Capybara will match elements outside of a page's <body> tag.

For example, the step definitions below match <link> nodes in a page's <head>:

Then /^my browser should auto-discover the "([^"]*)" feed$/ do |slug|
  page.should have_css(
    'head link' +
    '[rel="alternate"]' +
    "[href='http://www.example.com/#{slug}/feed.rss']" +
    '[title="RSS feed (all cards)"]' +
    '[type="application/rss+xml"]',
    visible: false
  )
end

Then /^my browser should not auto-discover any RSS fe...

Looks simpler than inaction_mailer:

gem install mailcatcher
mailcatcher

Setup Rails to send mails to 127.0.0.1:1025. Usually you want the following config in config/environments/development.rb and maybe in test.rb or cucumber.rb.

config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  :address => 'localhost',
  :port => 1025
}

Now you can see sent mails in your browser when opening http://127.0.0.1:1080

Note: In order to s...

Generally for nested forms, a blank form is placed below all other existing object forms. If you would like to change the position of the blank form(s) you can reorder the object's one-to-many association. For example you can put the blank form on top with the following snippet:

actors = movie.actors
actors.build
actors.unshift(actors.pop(1)) # won't work with Rails 4+

Because build_for_form creates new objects and ap...

Using git rebase can be painful but luckily you can resort to cheating with git reset and committing anew.
Now what if you wanted to rebase commits of other people and still wish them to be the authors of their code? Easy: make them the author of a commit you made.

When you have freshly staged changes that are ready to be committed, just use the --author switch:

git commit -m "Hello Universe" --author="Philip J Fry <someone@example.com>"

If...

The colors in Rails log files are helpful when watching them but, since they are ANSI color codes like ^[[4;36;1m, can be annoying when you are reading the logs with a tool that does just prints those control characters (like less or vim).

Remove them with sed:

cat staging.log | sed -r "s/\x1B\[([0-9]{1,3}((;[0-9]{1,3})*)?)?[m|K]//g"

This will print the log without colors to your terminal. You can pipe the result into less for example.

To have a file you can vim around with, just write that output into a new file:

ca...

Never use raise_error without specifying the Error you expect.

expect { do_a_lot_of_complicated_stuff }.to raise_error

will be green if you make any error in programming. E.g. a simple typo would make the test above green. The block will catch the Spec:: exception and the test will be happy.

Be sure to always have custom errors in your models and raise them in a manner that lets you know what went wrong.

expect { execute_payment! }.to raise_error(PayPal...