Notes posted to Ruby on Rails

This method does not correctly dup arrays

Watch out because this method does not correctly dup arrays values.

The bug can be reproduced with the following code:

hash = { 'a' => [1,2,3,4] }
dup  = hash.deep_dup
dup['a'].object_id == hash['a'].object_id # should return true

Rails 4 version does not have this issue because it is completely different implementation.

In Rails 4 it DOES return nil, even if the object you try from isn't nil

The try method does not raise a NoMethodError if you call a method that doesn’t exist on an object.

a = Article.new

a.try(:author) #=> #<Author ...>

nil.try(:doesnt_exist) #=> nil

a.try(:doesnt_exist) #=> nil

Note:

a.try(&:doesnt_exist) #=> Raises NoMethodError

False query string parameters removed

This method is used in url_for (therefore in redirects as well).

If you pass a query string parameter to a url route that is false, before Rails 3.1, the generate method would reject it.

This causes issues on the redirected page if you are depending on the param to be have a specific value.

In Rails 3.2 they remove params.reject! {|k,v| !v.to_param} altogether.

So every single param you send is a string.

callbacks

As a note, AFAICT, this skips “validations” but does still run all callbacks still [like after_save, etc.] So if you’re looking for something that just updates see here: http://stackoverflow.com/a/7243777/32453

Non-existent key semantics changed.

For Rails 4.0, the behaviour of this has changed when you pass a key that isn’t in the hash.

3.2 (undocumented):

{ a: 1, b: 2 }.extract!(:a, :x) # => {:a=>1, :x => nil}

4.0 (as per docs):

{ a: 1, b: 2 }.extract!(:a, :x) # => {:a=>1}

The 4.0 behaviour is now consistent with the behaviour of slice, the 3.2 behaviour was not.

Removed in Rails 3.1 and up

Use this instead

proxy_association.owner

Deprecated in favour of []

In Rails 3+

company.errors[:name]

In Rails 2.3 and below:

company.errors.on(:name)

Handling flash for ajax calls

This is helper method which can be easily used to handle flash for ajax calls

##call it in your js.erb
def flash_display
response = ""
flash.each do |name, msg|
	msg=msg+"<button type='button' class='close' title='hide' data- dismiss='alert'><i class='fa-times-circle-o fa pull-right'></i></button>".html_safe
  response = response + 
  content_tag(:div, msg, :id => "flash_# {name}",:class=>"alert alert-danger") do 
  	"#{msg}".html_safe  
  end 	
end
flash.discard
response
end

so in your controller,

def get_data_and_update_div
 @user_details=User.get_details
 if @user_details.nil?
   flash.now[:error]="Add your details and then submit"
   format.js { render   'shared/error_messages'}
 end

in error_messages.js.erb

$('#flash_messages').html("<%= escape_javascript raw(flash_display) %>");

in view file

<div id="flash_messages">
  <% if flash[:error] %>
   <%= content_tag :div, flash['value'], :id =>"flash_error" %>
 <% end %>
</div>

include respond_to in your controller action only if there are multiple formats of that view

consider this

def index
 @users=User.get_users
  respond_to do |format|
   format.html
   format.json
   format.js
  end
end

is good if you have a call to users/index by both

<%= link_to ("Show users",user_path)%>
##will render users/index.html.erb
===Also same call but with ajax
<%= link_to ("Show users",user_path,remote=>true)%>
 ##will render users/index.js.erb..handled by respond_to   block
===Also same call but with json
<%= link_to ("Show users",user_path,remote=>true,:format=>json)%>
##will render users/index.json.erb..handled by respond_to   block.

But if you have just first one,so remove respond_to block as you are sure that you only need index.html.erb ALWAYS

def index
  @users=User.get_users
end 

So if your action is being called both by BOTH ajax,non-ajax call,its good to use respond_to.

Using render to handle ajax call using same js.erb(DRY)

Suppose your application have many pages using some common view and is updated using ajax,so you can use a single js in multiple views to avoid duplication

format.js { render 'profile/show_user_details' }

And in my profiles/show_user_details.js i can use conditions instead of creating regular partials

<% if params[:controller]== "dashboard"%>
 $("admin_panel").show();
 $("user_panel").hide();
<% elsif params[:controller]== "user"%>
 $("admin_panel").hide();
 $("user_panel").show();
<% elsif params[:controller]== "video"%>
 $("admin_panel").hide();
 $("user_panel").hide();
 $("video_panel").show();
<% else %>
 $("admin_panel").hide();
 $("user_panel").hide();
 $("video_panel").hide();
<%end%>

simple use

Examples

<%= @user.created_at.to_date.to_formatted_s(:long_ordinal)%> => July 5th, 2014

OR

<%=@user.created_at.strftime("%b %d,%Y") %> =>  Jul 05,2014

quick ref:-

:db           # => 2008-12-25 14:35:05
:number       # => 20081225143505
:time         # => 14:35
:short        # => 25 Dec 14:35
:long         # => December 25, 2008 14:35
:long_ordinal # => December 25th, 2008 14:35
:rfc822       # => Thu, 25 Dec 2008 14:35:05 +0000

Using fontawesome icons inside link_to

<%= link_to (‘<i class=“fa fa-thumbs-up fa-lg”> </i>’).html_safe, vote_path(@image)%>

in this way you can use thumbs-up icon instead of usual text such as “like” in link_to

4.0.2 support

Where did this go in 4.0.2?

form_for with namescope and polymorphic path

<%= form_for([:namescope_name, @object], :url => polymorphic_path([:namescope_name, @objectable, @object])) do |form| %>

for the routes.

namescope :admin do

resources :articles do
  resources :comments
end
resources :photos do
  resources :comments
end

end

<%= form_for([:admin, @comment], :url => polymorphic_path([:admin, @commentable, @comment])) do |form| %>

Note : @commentable = find_commentable

change_column did the trick for me

Use change_column, and make sure to specify the datatype:

class ChangeUsers < ActiveRecord::Migration
  def up
	change_column :users, :is_vote_reminder, :boolean, :default => true
  end
end

Use this for has_one associations instead

I have confirmed that validates_associated doesn’t work with has_one associations, like @amasses said.

This however worked for me, so I recommend to use validates on the has_one association directly, like this:

class Book < ActiveRecord::Base
  has_one :cover, validates: true
end

URI Module

Uniform handling of handling URIs

Flexibility to introduce custom URI schemes

Flexibility to have an alternate URI::Parser

For Example

require ‘uri’

uri = URI(“http://test.com/posts?id=30&limit=5#time=1305298413”)

uri.scheme #=> “http”

uri.host #=> “test.com”

uri.path #=> “/posts”

time is represented in the Rails app's timezone

From the description of Time.current (which is a Rails extension of Ruby’s native Time class)

“Returns Time.zone.now when Time.zone or config.time_zone are set, otherwise just returns Time.now.”

so 3.days.ago, for example, is in the application’s configured timezone (if it’s configured).

Reject If

reject_if: proc { |attributes| attributes[‘name’].blank? } Has saved me after an 3 hours of google search. Thanks

Alternitive to to add flash to respond with

This is a nice way to add flash if you don’t have a any logic that needs to go around your flash.

def destroy
  @current_user_session.destroy
  respond_with @current_user_session do |format|
    format.html {redirect_to login_path, notice: "You have been logged out"}
  end
end

:hidden_field_id was replaced with :include_id

In order to prevent fields_for from rendering a hidden field to store the ID of the record use

include_id: false

instead of

hidden_field_id: false

Original URL Example

# get “/articles?page=2”

request.original_url # => “http://www.example.com/articles?page=2”

You can add if: :query_method and unless: :query_method

You can make the callback conditional:

before_save :before_method, if: :needs_before_method?

private

def needs_before_method?
   false
end

def before_method
  # .. 
end

How to set request parameters (rails 3.2)

In Rails 3.2, this seems to work to create a TestRequest based on a certain url:

ActionController::TestRequest.new( Rack::MockRequest.env_for("http://something.tld/foo?one=two&three=four") )    

Example Regex format matching

for phone and email

validates_format_of :phone, with: /\A(\d{10}|\(?\d{3}\)?[-. ]\d{3}[-.]\d{4})\z/
validates_format_of :email, with: /\A[\w]([^@\s,;]+)@(([\w-]+\.)+(com|edu|org|net|gov|mil|biz|info))\z/i

another way

Perhaps a more efficient way:

def create
  @post = Post.new(post_params)
  if @post.save
    redirect_to @post, notice: "The post #{@post.title} was added to the system."
  else
    render action: 'new'
  end
end

where post_params is:

private

def post_params
  params.require(:post).permit(..attributes to permit..)
end

Security

In regards to @aamer’s comment on including the password salt this is a bad idea. `ActiveSupport::MessageVerifier` is NOT encrypted so:

verifier = ActiveSupport::MessageVerifier.new('secret')
id = 'id'
salt = 'salt'
verifier.generate("#{id}-#{salt}") # "BAhJIgxpZC1zYWx0BjoGRVQ=--c880254708d18ce4a686bcd96a25cf0d2117e1e0"

Base64.decode64(token.split("--").first) # "...id-salt..."

Note how the salt and id are both exposed! Instead a different token (reset_passowrd_token) should be used.

Passing an array of keys to exclude.

Use the “*” before passing the array in. For example:

PARAMS_TO_SCRUB = [ :created_at, :updated, :id, :format ]

params.except!( *PARAMS_TO_SCRUB )

First example's output is incorrect

Everything except the initially html_safe input should be escaped in the output.

The output of the first example should be:

# => "<p>foo</p>&lt;br /&gt;&lt;p&gt;bar&lt;/p&gt;"

Does not symbolize hashes in nested arrays

If you have a nested structure containing arrays of hashes, you still need to do that on your own, eg.

module SymbolizeHelper
  def symbolize_recursive(hash)
    {}.tap do |h|
      hash.each { |key, value| h[key.to_sym] = map_value(value) }
    end
  end

  def map_value(thing)
    case thing
    when Hash
      symbolize_recursive(thing)
    when Array
      thing.map { |v| map_value(v) }
    else
      thing
    end
  end
end

Or, if you want to get really fancy with Ruby refinements (YMMV), one could do

module SymbolizeHelper
  extend self

  def symbolize_recursive(hash)
    {}.tap do |h|
      hash.each { |key, value| h[key.to_sym] = transform(value) }
    end
  end

  private

  def transform(thing)
    case thing
    when Hash; symbolize_recursive(thing)
    when Array; thing.map { |v| transform(v) }
    else; thing
    end
  end

  refine Hash do
    def deep_symbolize_keys
      SymbolizeHelper.symbolize_recursive(self)
    end
  end
end

And later say

using SymbolizeHelper # augmented Hash#deep_symbolize_keys is now available