Notes posted by nachocab

:selected

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})

link_to_remote renders javascript as text

If you want to render an RJS file with link to remote you shouldn’t specify the :update function. Using this:

link_to_remote('add',:update=> 'someId', :url => {:controller => 'my_controller', :action => 'new'} )
# assume having 'my_controller/new.rjs'

will return something like

try { Element.update("someElement\n"); } 
catch (e) { alert('RJS error:\n\n' + e.toString());  
alert('Element.update(\"someId\", \"item\\n\");');
throw e }

You should be specifying the id you are updating in the RJS file, not in link_to_remote. This will render correctly:

link_to_remote('add',:url => {:controller => 'my_controller', :action => 'new'} )
# assume having 'my_controller/new.rjs'

Only use :update when rendering html.

Mistake

It’s not:

user = User.find_by_name('Phusion')
user_path(path)  

It’s:

user = User.find_by_name('Phusion')
user_path(user)  

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.

rescue

Store exceptions using ‘rescue => var’

begin                              
  x = factorial(-1)             
rescue => ex                       
  puts "#{ex.class}: #{ex.message}"
end                                

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) 
end
#=> <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>

Routes = RouteSet.new

In config/routes.rb you can see this:

ActionController::Routing::Routes.draw do |map|
  #routes
end

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

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

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
  memo
end

hash
# => {'A' => 'a', 'B' => 'b', 'C' => 'c'}

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:

URL:/albums/209/songs/new
form_for [@album, @song] do |f| 
  ...
  f.submit "Add"
end

The params hash would be:

params = {"commit"=>"Add", 
          "authenticity_token"=>"...",
          "album_id"=>"209",
          "song"=>{"song_attributes"=>{...}}
          }

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

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

If you only did this:

form_for @song do |f| 

You would get this params hash:

params = {"commit"=>"Add", 
          "authenticity_token"=>"...",
          "song"=>{"song_attributes"=>{...}}
          }  

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"]

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