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July 23, 2009 - (v1.0.0 - v2.3.2)
0 thanks

Format meaning:

%a - The abbreviated weekday name (“Sun”)

%A - The full weekday name (“Sunday”)

%b - The abbreviated month name (“Jan”)

%B - The full month name (“January”)

%c - The preferred local date and time representation

%d - Day of the month (01..31)

%H - Hour of the day, 24-hour clock (00..23)

%I - Hour of the day, 12-hour clock (01..12)

%j - Day of the year (001..366)

%m - Month of the year (01..12)

%M - Minute of the hour (00..59)

%p - Meridian indicator (“AM” or “PM”)

%S - Second of the minute (00..60)

%U - Week number of the current year, starting with the first Sunday as the first day of the first week (00..53)

%W - Week number of the current year, starting with the first Monday as the firstday of the first week (00..53)

%w - Day of the week (Sunday is 0, 0..6)

%x - Preferred representation for the date alone, no time

%X - Preferred representation for the time alone, no date

%y - Year without a century (00..99)

%Y - Year with century

%Z - Time zone name

%% - Literal “%” character

July 23, 2009 - (v1.0.0 - v2.3.2)
7 thanks

Format meaning

%a - The abbreviated weekday name (“Sun”)

%A - The full weekday name (“Sunday”)

%b - The abbreviated month name (“Jan”)

%B - The full month name (“January”)

%c - The preferred local date and time representation

%d - Day of the month (01..31)

%H - Hour of the day, 24-hour clock (00..23)

%I - Hour of the day, 12-hour clock (01..12)

%j - Day of the year (001..366)

%m - Month of the year (01..12)

%M - Minute of the hour (00..59)

%p - Meridian indicator (“AM” or “PM”)

%S - Second of the minute (00..60)

%U - Week number of the current year, starting with the first Sunday as the first day of the first week (00..53)

%W - Week number of the current year, starting with the first Monday as the firstday of the first week (00..53)

%w - Day of the week (Sunday is 0, 0..6)

%x - Preferred representation for the date alone, no time

%X - Preferred representation for the time alone, no date

%y - Year without a century (00..99)

%Y - Year with century

%Z - Time zone name

%% - Literal “%” character

July 18, 2009
2 thanks

Sanitize in controllers, models, or libs -- *with* options

A Follow-up to k776’s note. If you want to specify tags or attributes, you should change your initializer to:

class String
  def sanitize(options={})
    ActionController::Base.helpers.sanitize(self, options)
  end
end

Then you can call it from any string like so:

'string'.sanitize(:tags => %w(table td tr), :attributes => %w(style id))
July 17, 2009
0 thanks

Like Groovy Expando

If you’re coming from Groovy/Grails: this is called an Expando in Groovy.

July 17, 2009
1 thank

Highlight keywords in a text

Case-insensitive

keywords.inject(text) { |text, keyword| text.gsub(/(#{keyword})/i, "<strong>\\1</strong>") }

<strong> can be replace by whatever HTML tag you want for hightlighting (<b>, <i>, …)

July 16, 2009
0 thanks

Also works with other markup

such as XML, not only HTML as suggested in the text.

July 16, 2009
0 thanks

Usage example

Usage example:

cube = lambda {|x| x * x * x } 
cube.call(3)  # => 27
cube.call(6)  # => 216
July 15, 2009
0 thanks

Time.now in views.

Be careful if you use Time.now in views with time zone support enabled, as this will not actually do the time zone conversion.

Instead, use Time.zone.now.

July 14, 2009
2 thanks

Not for floats

You should use assert_in_delta when comparing floating-point numbers.

July 13, 2009
1 thank

Any base logarithm

Using basic arithmetic you can get logarithm with any base:

def log_with_base base, num
  Math.log(num) / Math.log(base)
end

Examples:

>> log_with_base 2, 10
=> 3.32192809488736
>> log_with_base 2, 2
=> 1.0
>> log_with_base 2, 4
=> 2.0
>> log_with_base 2, 16
=> 4.0
>> log_with_base 4, 16
=> 2.0
July 13, 2009
0 thanks

Any base logarithm

Using basic arithmetic you can get logarithm with any base:

def log_with_base base, num
  Math.log(num) / Math.log(base)
end

Examples:

>> log_with_base 2, 10
=> 3.32192809488736
>> log_with_base 2, 2
=> 1.0
>> log_with_base 2, 4
=> 2.0
>> log_with_base 2, 16
=> 4.0
>> log_with_base 4, 16
=> 2.0
July 8, 2009
0 thanks

Change Column. pt-br

Em sua migration escreva da seguinte forma:

Exemplo de uso.

def self.up
  change_column :sua_tabela, :seu_campo, :seu_tipo_campo
end
July 8, 2009
1 thank

Change Column.

Into your migration write the follow:

Using Exemple

def self.up
  change_column :yourtable, :your_field, :your_type_field
end
July 8, 2009
1 thank

This is an alias

Please comment under the real method instead: find_index

July 8, 2009 - (<= v1_8_7_72)
5 thanks

Using block version in Ruby < 1.8.7

The block usage was added in 1.8.7, so to get the same functionality in an earlier version of Ruby, you need to utilize the find method.

Here is a quick example:

match = list.find { |l| l.owner == myself }
match_index = list.index(match)

If you do some gymnastics, you can have it on one line without extra variables:

match_index = list.index(list.find { |l| l.owner == myself })
July 7, 2009 - (<= v2.3.2)
5 thanks

Options

Available options are (none of these exists by default):

* :limit - Requests a maximum column length. This is number of characters for :string and :text columns and number of bytes for :binary and :integer columns.
* :default - The column‘s default value. Use nil for NULL.
* :null - Allows or disallows NULL values in the column. This option could have been named :null_allowed.
* :precision - Specifies the precision for a :decimal column.
* :scale - Specifies the scale for a :decimal column.
July 7, 2009
0 thanks

Pretty Printing Routes

if you’d like to check out your routes in the console, you can do something like:

routes = ActionController::Routing::Routes

# which will return a RouteSet puts routes.routes

which’ll give you a nice output like: GET /messages/ {:action=>“index”, :controller=>“messages”} GET /messages.:format/ {:action=>“index”, :controller=>“messages”} POST /messages/ {:action=>“create”, :controller=>“messages”} POST /messages.:format/ {:action=>“create”, :controller=>“messages”} GET /messages/new/ {:action=>“new”, :controller=>“messages”} GET /messages/new.:format/ {:action=>“new”, :controller=>“messages”} GET /messages/:id/edit/ {:action=>“edit”, :controller=>“messages”} GET /messages/:id/edit.:format/ {:action=>“edit”, :controller=>“messages”} GET /messages/:id/ {:action=>“show”, :controller=>“messages”} GET /messages/:id.:format/ {:action=>“show”, :controller=>“messages”} PUT /messages/:id/ {:action=>“update”, :controller=>“messages”} PUT /messages/:id.:format/ {:action=>“update”, :controller=>“messages”} DELETE /messages/:id/ {:action=>“destroy”, :controller=>“messages”} DELETE /messages/:id.:format/ {:action=>“destroy”, :controller=>“messages”}

July 5, 2009
2 thanks

To verify if the element exists before replacing.

Just add this code into a initializer file.

Atention: The code starts at the “module ActionView” and the last “end” has to be copied too.

module ActionView

module Helpers
  module PrototypeHelper
    class JavaScriptGenerator #:nodoc:
      module GeneratorMethods
        def replace_html_if_exists(id, *options_for_render)
          call "if($('#{id}')) Element.update", id, render(*options_for_render)
        end
      end
    end
  end
end

end

July 1, 2009
4 thanks

Example

User = Struct.new(:name, :phone)

marc = User.new(“Marc”, “555-5555”)

June 30, 2009
3 thanks

Be careful with name of attribute writer

If restricting access to attributes you normally get code like

attr_accessible :foo,  

When using these nested attributes you end up with code like

attr_accessible :foo, :bar_attributes

Its very easy to leave of the _attributes suffix e.g

attr_accessible :foo, :bar

which will cause you all sorts of problems

June 29, 2009
0 thanks

: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})
June 25, 2009
1 thank

Returns a copy of the attribute contents

As szeryf notes, this is a really expensive method, but another important remark is that the contents returned are a copy of the actual values.

model.attributes['name'] # => 'Joe'
model.attributes['name'] = 'Jim'
model.attributes['name'] # => 'Joe' still
model.name # => 'Joe'

This has the potential to be confusing as you’re given the impression you have direct access to the attributes.

June 25, 2009
2 thanks

Antonym of empty?

The antonym of empty? is Enumerable#any? method:

[].empty?  #=> true
[].any?    #=> false
[1].empty? #=> false
[1].any?   #=> true

Be cautious however, if your array might contain nil’s or false’s:

[false, nil].any? #=> false
June 25, 2009 - (>= v2.3.2)
1 thank

Validate() is run always before one of the more specific validation methods

I did not see this mentioned explicitly anywhere.

The method validate is run always before a call to validate_on_create or validate_on_update is made.

Example:

class Foo < ActiveRecord::Base
  def validate
    puts 'In validate'
  end

  def validate_on_create
    puts 'In validate_on_create'
  end

  def validate_on_update
    puts 'In validate_on_update'
  end
end

Now, when creating a new Foo using script/console, the output is as follows:

In validate
In validate_on_create

and when updating a Foo, the output looks like:

In validate
In validate_on_update
June 22, 2009
3 thanks

Optional local assigns

When you have a partial with optional local assigns, for instance:

<%= render :partial => 'articles/preview' %>
<%= render :partial => 'articles/preview', :locals => { :show_call_out => true } %>

And you don’t want the partial to break when the local isn’t assigned, you can reference it through the local_assigns local variable instead of through the template binding:

<% if local_assigns[:show_call_out] %>
  <em><%= format @article.call_out %></em>
<% end %>
June 19, 2009
1 thank

Usage example

class Aa

 class_inheritable_accessor :test
end
=> [:test]

Aa.test = 10
=> 10

Aa.test
=> 10

Bb = Class.new(Aa)
=> Bb

Bb.test
=> 10

Bb.test = 5
=> 5

Bb.test
=> 5

Aa.test
=> 10
June 19, 2009
2 thanks

Re: How to test different responses

In addition to using:

@request.accept = "text/javascript" #=> request JS

as rubymaverick and nachocab suggested, you can also pass :format when calling your action, eg:

it "GET #most_viewed renders #most_viewed.js.rjs template if js requested" do
  get :most_viewed, :format => 'js'
  response.should render_template('most_viewed')
end
June 18, 2009
3 thanks

Not really deprecated

This isn’t really deprecated, it’s just relocated to ActiveRecord::AttributeMethods#read_attribute

June 18, 2009
12 thanks

Important note

It has been said that “it can be compared to, but isn’t the same thing as”:

class Bar
  class << self
    attr_accessor :greeting
  end
end

Which is true. However, they are “inherited” isn’t exactly the case. Rather, cattr_accessor uses class variables.

The problem with class variables in Ruby, is that a class variable is the same object across all subclasses of a class. Consider the following example of what happens with cattr_accessor:

class A
  @@foo = 'foo'

  def self.foo
    @@foo
  end
end

p A.foo # => "foo"

class B < A
end

p B.foo # => "foo"

class B
  @@foo = 'bar'
end

p B.foo # => "bar"

So far so good you might think. However, something you might not have expected is that the variable has now also changed in class A:

p A.foo # => "bar"

This is in my opinion almost never what you’d want. More probable is that you’d want the individual class instance to have an accessor. (Remember classes are objects in Ruby). I do the following in regular Ruby:

class A
  class << self
    attr_accessor :foo
  end

  self.foo = 'foo'
end

p A.foo # => "foo"

class B < A
end

p B.foo # => nil

class B
  self.foo = 'bar'
end

p B.foo # => "bar"

p A.foo # => "foo"

As you can see, this returns nil when a value hasn’t explicitly been set yet on the new class instance. If you’d like to have inheritance without messing with the superclasses variables, have a look at ActiveSupport’s class_inheritable_accessor, which does the same as I just explained, but creates a clone of the object and assigns it to the subclass whenever a class is inherited.

What I’d normally do in Ruby to fix the issue of it returning nil is to create the accessor manually and have it set the instance variable to the default if it’s nil:

class A
  class << self
    def foo
      @foo ||= 'foo'
    end
  end
end

class B < A
end

p B.foo # => nil

So to recap:

  • cattr_accessor uses class variables (@@foo), in which case the object is shared across all subclasses of a class. Use it mainly for static data, in which case you’d probably best use a constant.

  • class_inheritable_accessor (or what I showed) uses instance variables (@foo) at the Class instance level. These variables are not shared across all subclasses.

June 18, 2009
1 thank

Expensive method!

This method builds the a new hash every time it’s called, so be cautious not to use it in loops etc.