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Free Ruby on Rails security e-book

The the ever so useful Ruby on Rails security blog, rorsecurity, has released a free e-book.

Hoptoad - Free ruby on rails exception catcher

I've been using the exception_notification plugin for sometime now. It's been a life saver on many occassion, allowing me to be made aware of bugs at the earliest opportunity.

However, there are occassions where you don't necessarily require multiple emails all notifying you of the same problem. This is where Hoptoad comes in handy.

It catches all your exceptions and holds them online, grouping them together and giving you a single notification.

It's free and easy to 'drop in' as a replacement for exception notifier.

Can't activate rubyforge

I just tried to start one of my rails apps and got...

Can't activate rubyforge (= 0.4.4, runtime), already activated rubyforge-1.0.0 (Gem::Exception)

I fixed it by uninstalling rubyforge completely and thus getting rid of version 0.4.4 and reinstalling to have just version 1.0.0.

sudo gem uninstall -a rubyforge

Confirming that I didn't mind the warning that 'one or more dependencies will not be met'.

Then reinstalling it with...

sudo gem install rubyforge

"Only get, head, post, put, and delete requests are allowed. Ruby on Rails error"

Every so often I get the rather odd Ruby on Rails error "Only get, head, post, put, and delete requests are allowed."

So far, each time a simple restart of my local server has done the trick and made it go away.

Using or equals (||=) to set variables in Ruby on Rails

Using 'or equals' is great for creating and setting variables when they don't exist - useful for default values.

>>foo
=>NameError: undefined local variable or method `foo' for main:Object
>>foo ||= "bar"
=>"bar"

If variable already exists then it isn't overwritten:

>>foo = "hello"
=> "hello"
>>foo ||= "goodbye"
=>"hello"

I use this in partials sometimes where I'm expecting a local variable to be passed in but if there isn't one I'd like there to be a default.

It also means if the variable isn't passed in then you wont get an undefined error.

However, there is a gotcha you want to look out for. Observe:

>>foo = false
=> false
>>foo ||= true
=>true

The or equals actually checks if the left hand side evaluates to true and if so it isn't changed.

So the or equals is not useful for booleans. It's not difficult to work around that but it is something to keep in mind...

>> foo = false
=> false
>> foo = true if foo.nil?
=> false

Not quite as nice but it's one way to do the job.

Some handy shortcuts for Textmate, Vim and the command line.

These are probably my most used shortcuts:

Textmate

ctrl+shift+> = open and close erb tags <% = %>

alt+command+] = auto indent highlighted code

ctrl+shift+w = auto put html tags around highlighted code

alt+command+> = auto close tag

ctrl+command+w = close all open tabs

alt+command+a = type on the end of multiple lines of highlighted code

VIM

o - is new line

d, shift g - clears the file (d is delete and capital g is bottom of the file)

:set number - turn on line numbers

18, shift g - goes to line 18

dd - deletes a line

Command line

ctrl+r - searches through recent commands (repeat to keep searching)

ctrl+a - beginning of the line

ctrl+e - end of line

Viewing the documentation for your installed gems for Ruby on Rails

To view the rdoc for your installed gems, at the command line type:

gem server

Then point your browser at http://localhost:8808

Using routes in models in Ruby on Rails

To use routes in your model just add the following to config/environment.rb...


class ActiveRecord::Base
 include ActionController::UrlWriter

 host = case ENV['RAILS_ENV']
 when "production"
   "yourlivedomain.com"
 when "development"
   "localhost:3000"
 end
 default_url_options[:host] = host
end

Assigning a body class to your page layout in Ruby on Rails

In your controller create a private method thus:

private

def add_body_class(new_class)
  @body_class ||= ""
  @body_class << " #{new_class}"
end

Then in your controller actions you can add a body class with:

add_body_class "two_col"

The reason for the add_body_class method is so that you can easily add multiple classes without worrying if you have already set the body_class instance variable.

I find this useful because quite often I will use a before filter to set a generic body class for every action in the controller...

before_filter :set_body_class

private
def set_body_class
  add_body_class "some_section_name"
end

To output @body_class replace your layout body tag with this:

<body<%= (@body_class.nil?) ? "" : " class='#{@body_class}'" %>>

That's basically a one line if statement that checks if @body_class exists before setting the class on the body tag.

Getting Ruby on Rails & mysql setup on a Mac OSX Leopard clean install

So Rails is already installed on Leopard but you'll probably want to update it to the latest version. So first you need to install the make tools from your Leopard disc:

Leopard CD > Optional Installs > Xcode Tools > XcodeTools.mpkg

Update Rails and all the other gems:

sudo gem update --include-dependencies

Now for mysql. You can download a pre-built package from their site http://dev.mysql.com/downloads/mysql/5.0.html#macosx-dmg

Note that you don't have to register - you can skip past it using the link after the form.

The start up package doesn't work (at the time of writing). However, I found a work around. I'll include the instructions here as well:

First download this MySQL launchd configuration file

sudo mv Downloads/com.mysql.mysqld.plist /Library/LaunchDaemons/
sudo chown root /Library/LaunchDaemons/com.mysql.mysqld.plist
sudo chown -R mysql /usr/local/mysql-5.0.51a-osx10.5-x86/ /usr/local/mysql
sudo launchctl load /Library/LaunchDaemons/com.mysql.mysqld.plist

To allow you to just type 'mysql' from the command line:

vi ~/.bash_profile

Enter the following into the file

export PATH="$PATH:/usr/local/mysql/bin"

Restart terminal and mysql is all setup and will start every time you reboot.

DHH recommends you install the mysql C bindings like thus:

sudo env ARCHFLAGS="-arch i386" gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config

Job done!

Leopard comes with mongrel and svn and lots of other goodies out of the box! Have a look with:

gem list