Notes posted by nachocab

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June 29, 2009
2 thanks


If you want some object to be selected by default, be sure to use its id, not the whole object.

 collection_select(:post, :author_id, Author.all, :id, :name_with_initial, {:selected => current_book.authors.map(&:id)})
#=> :selected => [1,2,3,4]

and not

collection_select(:post, :author_id, Author.all, :id, :name_with_initial, {:selected => current_book.authors})
March 5, 2009
1 thank


It’s not:

user = User.find_by_name('Phusion')


user = User.find_by_name('Phusion')
February 28, 2009
0 thanks

Exceptions while debugging

If the error wasn’t stored in a variable, you can still see it by looking at the global variable $ERROR_INFO.

February 28, 2009
1 thank


Store exceptions using ‘rescue => var’

  x = factorial(-1)             
rescue => ex                       
  puts "#{ex.class}: #{ex.message}"
January 27, 2009
7 thanks

Use collect in nested content_tags

Remember to use #collect instead of #each in nested content_tags

arr = ['a','b','c']
content_tag :div do 
  arr.collect { |letter| content_tag(:scan, letter) 
#=> <div>
#      <scan>a</scan>
#      <scan>b</scan>
#      <scan>c</scan>
#   </div>

If you used #each you would get this (which is probably a mistake):

#=> <div>
#      abc
#   </div>
January 25, 2009
3 thanks

Routes = RouteSet.new

In config/routes.rb you can see this:

ActionController::Routing::Routes.draw do |map|

If you want to look at the code in ActionController::Routing you won’t find the definition of Routes. That’s because it’s actually an instance of the class RouteSet, defined in action_controller/routing.rb

Routes = RouteSet.new
January 24, 2009
8 thanks

How to test different responses of respond_to

You can shorten this:

@request.env['HTTP_ACCEPT'] = "application/rss"

To this:

@request.accept = "application/rss"

Also, if you send more than one Mime type, it will render the first one:

@request.accept = "text/javascript, text/html" #=> renders JS
@request.accept = "text/html, text/javascript" #=> renders HTML
December 6, 2008
5 thanks

Array expansion in blocks

The syntax can be improved as changing the second parameter of the block (values) and using an array of two variables instead, which will be used by Ruby as the key and value of “array”.

array = [['A', 'a'], ['B', 'b'], ['C', 'c']]

hash = array.inject({}) do |memo, (key, value)|
  memo[key] = value

# => {'A' => 'a', 'B' => 'b', 'C' => 'c'}
November 2, 2008
2 thanks

params hash gets the model id automatically

The params hash gets automatically populated with the id of every model that gets passed to form_for. If we were creating a song inside an existing album:

form_for [@album, @song] do |f| 
  f.submit "Add"

The params hash would be:

params = {"commit"=>"Add", 

So, in the songs_controller you could use this album_id in a before_filter:

before_filter :find_album
def find_album
  @album = Album.find(params[:album_id])

If you only did this:

form_for @song do |f| 

You would get this params hash:

params = {"commit"=>"Add", 
November 2, 2008 - (v1_8_6_287)
1 thank

The reverse operation of split is join.

Given that String#split returns an array, its reverse operation is Array#join. Example:

"life is awesome".split

["life","is","awesome"].join(" ")
=>"life is awesome"