modsaid · January 2, 2016 07:59 · Jan 5, 2014 · Jan 2, 2014 · Jan 2, 2014 · Jan 2, 2014
diff --git a/scope.rb b/scope.rb
@@ -15,8 +15,15 @@
 scope :un_deleted, where(delete_flag: false)
 scope :newly_products, -> { |start_date = 1.week.ago| where("created_at > ?", start_date) } # Yes the scope parameter can have a default
 scope :unavailable, where(delete_flag: true)
+
+# Default Scope
+# The default_scope is also applied while creating/building a record. It is not applied while updating a record.
+# So, in the following example, new records will have delete_flag set to false upon creation 
 default_scope :available, where(delete_flag: false)
 
+Product.create().delete_flag  # Will be false
+
+
 products = Product.for_brand("apple").price_bigger_than(1000).newly_products
 
 # What if we want to override the default scope?!

diff --git a/README b/README
@@ -1 +1 @@
-# text
+Rails as it has never been before :)
diff --git a/scope.rb b/scope.rb
@@ -12,15 +12,15 @@
 # GOOD
 scope :price_bigger_than, -> { |min_price| where("price > ?", min_price) } # Yes you can pass parameter to scope
 scope :for_brand, -> { |brand| where(brand: brand) }
-default_scope :un_deleted, where(delete_flag: false)
-scope :new, -> { |start_date = 1.week.ago| where("created_at > ?", start_date) } # Yes the scope parameter can have a default
-scope :available, where(delete_flag: false)
+scope :un_deleted, where(delete_flag: false)
+scope :newly_products, -> { |start_date = 1.week.ago| where("created_at > ?", start_date) } # Yes the scope parameter can have a default
 scope :unavailable, where(delete_flag: true)
+default_scope :available, where(delete_flag: false)
 
-products = Product.for_brand("apple").price_bigger_than(1000).available.new
+products = Product.for_brand("apple").price_bigger_than(1000).newly_products
 
 # What if we want to override the default scope?!
-# Get all apple unavailable products 
+# Get all apple unavailable products
 
 products = Product.for_brand("apple") # Wont work, will get only the available
 products = Product.for_brand("apple").unavailable # Wont work too, will get only the available
@@ -37,7 +37,7 @@
 
 # Note: -> AND lambda are equivalent
 
-# You can define scope dynamically 
+# You can define scope dynamically
 # Example for an api with api_keys
 Status = { normal: 0, whitelisted: 1, blacklisted: 2}
 Status.each_pair do |k,v|

diff --git a/README b/README
@@ -1 +1 @@
-# text
+Rails as it has never been before :)
diff --git a/README b/README
@@ -0,0 +1 @@
+# text
diff --git a/README b/README
@@ -0,0 +1 @@
+# text
diff --git a/clojure.rb b/clojure.rb
@@ -14,7 +14,7 @@ def do_math_operation(amount, &block)
 # The same above can be done using proc
 
 def do_math_operation(amount, proc)
-  block.call(amount) # yield won't work!
+  proc.call(amount) # yield won't work!
 end
 
 multiply_by_2 = Proc.new do |n|
@@ -26,7 +26,7 @@ def do_math_operation(amount, proc)
 
 # The same above can be done using lambda
 def do_math_operation(amount, lambda)
-  block.call(amount) # yield won't work!
+  lambda.call(amount) # yield won't work!
 end
 
 multiply_by_2 = lambda{ |n| n * 2 }
@@ -77,4 +77,4 @@ def multiply_by_2(n)
 result = do_math_operation(5, method(:multiply_by_2))
  => 10
 
-# Method objects will act like lambda , only lambda is anonymous
+# Method objects will act like lambda , only lambda is anonymous
diff --git a/presenter.rb b/presenter.rb
@@ -66,5 +66,5 @@ def present(object, klass = nil)
 private
  def present(object, klass = nil)
    klass ||= "#{object.class}Presenter".constantize
-   klass.new(view_context, object)
+   klass.new(object, view_context)
  end
diff --git a/validation.rb b/validation.rb
@@ -1,4 +1,5 @@
-s# Not good
+# Not good
+
 class User < ActiveRecord::Base
   validates :appropriate_content
 
@@ -22,4 +23,4 @@ def validate_each(record, attr, value)
       record.errors.add(:attr, "is inappropriate")
     end
   end
-end
+end
diff --git a/meta_tags.rb → meta_tag.rb b/meta_tags.rb → meta_tag.rb
@@ -1,23 +1,31 @@
 # It is common in any rails application to have some meta tags in your HTML as title, description, keywords , fb meta tags,...
 
 # BAD
-# in app/views/layouts/application.html.erb
+# In app/views/layouts/application.html.erb
 <meta name="description" content="<%= @description%>" />
 <meta property="og:image" content="<%= @image_url %>" />
-# in each controller
+# In each controller
 @description = 
 @image_url =
 
-# Better but bad
+# Better
 # in app/views/layouts/application.html.erb
 <meta name="description" content="<%= yield(:description) %>" />
 <meta property="og:image" content="<%= yield(:image_url) %>" />
 # In each view
 content_for(:title, @product.title)
 content_for(:title, @product.description)
 
-# Best
+# Better
+
+<%=
+  og_tags(standard_og_stuff(@product), {
+    :type => 'website',
+    :other_tag => 'something'
+  })
+%>
 
+# app/helpers/application_helper.rb
 def og_tags(*tags)
   content = tags.reduce({}) do |result, set|
     result.merge! set
@@ -31,15 +39,7 @@ def og_tags(*tags)
 # Then a helper method that pulls standard attrs (name, desc, image, ...) from a piece of content:
 
 def standard_og_stuff(content)
-  {:title => content.name,
-   :description => content.description
+  { title: content.name,
+    description: content.description
   }
-end
-Then combine in view:
-
-<%=
-  og_tags(standard_og_stuff(@product), {
-    :type => 'video.tv_show',
-    :other_tag => 'something'
-  })
-%>
+end
diff --git a/scope.rb b/scope.rb
@@ -14,8 +14,8 @@
 scope :for_brand, -> { |brand| where(brand: brand) }
 default_scope :un_deleted, where(delete_flag: false)
 scope :new, -> { |start_date = 1.week.ago| where("created_at > ?", start_date) } # Yes the scope parameter can have a default
-default_scope :available, where(delete_flag: false)
-default_scope :unavailable, where(delete_flag: true)
+scope :available, where(delete_flag: false)
+scope :unavailable, where(delete_flag: true)
 
 products = Product.for_brand("apple").price_bigger_than(1000).available.new
 
@@ -30,7 +30,7 @@
 # Now we want to get products updated today
 # One can make
 scope :most_updated, where("updated_at > ?", Date.today) # Watch Out!!!
-# A scope is defined at initialisation, so what you start up your server, console, or in my case the DelayedJob worker, Date.today gets executed once and a scope is created called due that will return all the Books that are due on the day you start the process
+# A scope is defined at initialization, so as you start up your server. Date.today gets executed once and a scope is created so a call to most_updated will return all the products that are updated on the day you start the server!
 
 # This must be me done using Lambda OR without scopes
 scope :most_updated, -> { where("updated_at > ?", Date.today) }
@@ -39,13 +39,9 @@
 
 # You can define scope dynamically 
 # Example for an api with api_keys
-Status = {:normal => 0, :whitelisted => 1, :blacklisted => 2}
+Status = { normal: 0, whitelisted: 1, blacklisted: 2}
 Status.each_pair do |k,v|
-  scope "status_#{k}", where(:status => v)  # ApiKey.status_whitelisted,...
-
-  define_singleton_method "status_#{k}?" do |st|  # ApiKey.status_whitelisted?(status),...
-    v == st
-  end
+  scope "status_#{k}", where(status: v)  # ApiKey.status_whitelisted,...
 
   define_method "status_#{k}?" do # api_key.status_whitelisted?,...
     self.status == v

diff --git a/validation.rb b/validation.rb
@@ -4,7 +4,7 @@ class User < ActiveRecord::Base
 
   def appropriate_content
     unless # some validation check on name
-      self.errors.add(:name, "is inappropriate")
+      self.errors.add(:name, 'is inappropriate')
     end
   end
 end
@@ -15,7 +15,7 @@ class User < ActiveRecord::Base
   validate :name, appropriate: true
 end
 
-# /lib/appropriate_validator
+# /lib/appropriate_validator.rb
 class AppropriateValidator < ActiveRecord::EachValidator
   def validate_each(record, attr, value)
     unless # some validation check on value

diff --git a/performant_model.rb b/performant_model.rb
@@ -19,16 +19,18 @@
 
 
 # Counter Caching
-# we want to get the number of followers of a user
+# we want to get the number of retweets of a tweet
 
 # BAD
-user.followers.length # Load the followers into array and then call .length on that array
+tweet.retweets.length # Load the tweets into array and then call .length on that array
 
 # Better
-user.followers.size OR user.followers.count # make a count query to the db
+tweet.retweets.size OR tweet.retweets.count # make a count query to the db
 
 # What if the above query is made in a loop? many queries right?
 # Best using counter caching
-# Add column followers_count to the user model
-belongs_to "user", class_name "User", foreign_key: "user_id", counter_cache: :followers_count
-user.followers.size # no query , only look at the cache
+# Add column retweets_count to the tweet model
+# app/models/tweet.rb
+belongs_to :original_tweet, class_name: 'Tweet', foreign_key: 'tweet_id', counter_cache: :retweets_count
+has_many :retweets, class_name: 'Tweet', foreign_key: 'tweet_id'
+tweet.retweets.size # No query , only look at the cache as the 'tweet' object is already fetched
diff --git a/presenter.rb b/presenter.rb
@@ -1,32 +1,33 @@
 # Presenters are created by Controllers/Views and know the current state of the view and the model
-# Can be used to filter away out of tangled logic in the view
+# Can be used to filter away tangled logic in the view
 # Also can be used to skin the controller
 
 # An example of a presenter used to remove logic from view(this is a small example , views can get it even more bloated with logic)
 # app/views/categories/index.html
 <div class="images">
   <%if @category.image_url%>
-    <%= link_to image_tag("/images/#{category.id}.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
+    <%= link_to image_tag("/images/#{@category.id}.png") + "some extra text", category_path(@category), class: 'class-name', remote: true %>
   <%else%>
-    <%= link_to image_tag("/images/default.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
+    <%= link_to image_tag("/images/default.png") + "some extra text", category_path(@category), class: 'class-name', remote: true %>
   <%end%>
 <div>
 
 # app/presenters/category_presenter.rb
 class CategoryPresenter < BasePresenter
   presents :category
+
+  def featured_image
+    image_path = category.image_url ? category.id : "default"  
+    link_to image_tag("/images/#{image_path}.png") + "some extra text", category_path(category), :class => 'class-name',     :remote => true
+  end
+
   def top_brands
     @top_brands ||= category.top_brands
   end
 
   def top_keywords
     @top_keywords ||= category.top_keywords
   end
-
-  def featured_image
-    image_path = category.image_url ? category.id : "default"  
-    link_to image_tag("/images/#{image_path}.png") + "some extra text", category_path(@category), :class => 'class-name',     :remote => true
-  end
 end
 
 class BasePresenter
@@ -57,8 +58,7 @@ def method_missing?(*args, &block)
 def present(object, klass = nil)
  klass ||= "#{object.class}Presenter".constantize
  presenter = object.new(object, self)
- yield presenter if block_given?
- presenter
+ yield(presenter)
 end
   
 # To access presenters from controller

diff --git a/decorator.rb b/decorator.rb
@@ -1,14 +1,31 @@
+# Decorators let you layer on functionality to existing operations, i.e serve a similar purpose to callbacks.
+# For cases where including callback logic in the model would give the model too many responsibilities, a Decorator is useful.
+
 # Imagine we have this logic on stackoverflow:
 # A user can post a question on a stackoverflow, after posting an email notification is sent to
 # all users have interest in the question topic, a post is shared on the user profile with a link to the question he posted
 
+# BAD
+# app/models/question.rb
+after_create :handle_after_create_logic
+private
+  def handle_after_create_logic
+    # queue email to be sent
+    # create post
+  end
+# The question model should not be responsible for all this logic
+
+# Good
 class SOFQuestionNotifier
   def initialize(question)
     @question = question
   end
 
   def save
-    @question.save && post_to_wall && queue_emails
+    if @question.save
+      post_to_wall
+      queue_emails
+    end
   end 
 
 private

diff --git a/policy.rb b/policy.rb
@@ -1,4 +1,10 @@
+# Sometimes complex read operations might deserve their own objects, Policy Object is the right solution.
+# Policy Objects are similar to Service Objects, but it is conventional to use services for write operations
+# and policies for read.
+# They are also similar to Query Objects, but Query Objects focus on executing SQL to return a result set,
+# whereas Policy Objects operate on domain models already loaded into memory.
 # app/policies/twitter_policy.rb
+
 class TwitterPolicy < Struct.new(:auth)
 
   def first_name
@@ -16,7 +22,7 @@ def last_name
 # app/policies/facebook_policy.rb
 class FacebookPolicy < Struct.new(:auth)
   def first_name
-    auth['info']['name'].split(' ').first
+    auth['info']['first_name']
   end
 
   def last_name
@@ -32,4 +38,5 @@ def self.from_oauth(auth)
   create_user_from_policy(policy)
 end
 
-# check https://github.com/elabs/pundit for maximum usage of policies
+# Check https://github.com/elabs/pundit for maximum usage of policies and OO design
+# Pundit: Minimal authorization through OO design and pure Ruby classes
diff --git a/service.rb b/service.rb
@@ -1,19 +1,31 @@
-v# User service object when:
-# 1- The action is complex
-# 2- The action reaches across multiple models (e.g. an e-commerce purchase using Order, CreditCard and Customer objects)
+# Use service object when:
+# 1- The action is complex.
+# 2- The action reaches across multiple models.
 # 3- The action interacts with an external service (e.g. posting to social networks)
 # 4- The action is not a core concern of the underlying model (e.g. sweeping up outdated data after a certain time period).
 # 5- There are multiple ways of performing the action (e.g. authenticating with an access token or password). 
 
-class UserCSVDump < Struct.new(:users)
-  def csv
-    CSV.generate do |csv|
-      csv << %w[id username email]
-      users.each do |user|
-        csv << [user.id, user.username, user.email]
-      end
-    end
+class Authentication
+  def initialize(params, omniauth = nil)
+    @params = params
+    @omniauth = omniauth
   end
-end
 
-# Another example would be a class to manage authentication
+  def user
+    @user = @omniauth ? user_from_omniauth : user_with_password
+  end
+
+  def authenticated?
+    user.present?
+  end
+
+private
+
+  def user_from_omniauth
+    # Authenticate with omniauth
+  end
+
+  def user_with_password
+    # Authenticate with password
+  end
+end
diff --git a/law_of_demeter_model.rb → demeter_model.rb b/law_of_demeter_model.rb → demeter_model.rb
@@ -1,10 +1,12 @@
 # Law Of Demeter: Every unit should have limited knowledge about other units, simply don't talk to strangers!
+# 2 dots are fair enough!
 
 # BAD
 class Invoice < ActiveRecord::Base
  belongs_to :user
 end
 
+# In model/view
 invoice.user.name
 
 # Good

diff --git a/concern_module.rb b/concern_module.rb
@@ -1,4 +1,5 @@
 # app/models/concerns/users/csv_conversion.rb
+
 class User
   module CsvConversion
     extend ActiveSupport::Concern
@@ -19,18 +20,19 @@ def to_csv(options = {})
 # app/models/user.rb
 include CsvConversion
 
-
+# Use modules for more complex and widely used logic
 
 # Using modules/plugins
 # in lib/plugins/sponsorable.rb
 module Sponsorable
   extend ActiveSupport::Concern
   module ClassMethods
     def acts_as_sponsorable(configuration = {})
-      # do your logic and define the needed associations ex: product has many sponsors,
-      # a sponsor may sponsor many products , yes a polymorphic association
+      # Do your logic and define the needed associations ex: product has many sponsors,
+      # A sponsor may sponsor many products , yes a polymorphic association
     end
-    # if you forgot this line all instances of ActiveRecord::Base will have these methods !
+
+    # If you forgot this line all instances of ActiveRecord::Base will have these methods !
     include InstanceMethods
   end
 
@@ -39,12 +41,13 @@ def sponsors_count
    end
   end
 end
-ActiveRecord::Base.send :include, Sponsorable
+
+ActiveRecord::Base.send(:include, Sponsorable)
 
 # config/initializers/extension.rb
 require 'sponsorable'
 
 # app/models/product.rb
-acts_as_sponsorable({max_count: 5, sponsors_type: "exclusive"})
+acts_as_sponsorable({ max_count: 5, sponsors_type: 'exclusive' })
 
 # Use modules/plugins for shared complex logic and use concerns for model related simple logic
diff --git a/clojure.rb b/clojure.rb
@@ -1,15 +1,17 @@
-# If the last parameter in a method definition is prefixed with an ampersand, any associated block is converted to a Proc object, # and that object is assigned to the parameter. It must be the last argument in the parameter list
+# If the last parameter in a method definition is prefixed with an ampersand, any associated block 
+# is converted to a Proc object and that object is assigned to the parameter.
+# It must be the last argument in the parameter list
 def do_math_operation(amount, &block)
   block.call(amount) # OR yield(amount)
 end
 
 result = do_math_operation(5) {|amount| amount * 2}
  => 10
 
-# a proc is a reusable object oriented block , a block is a proc that can't be saved
+# A proc is a reusable object oriented block , a block is actually a proc that can't be saved
 block.class => Proc
 
-# the same above can be done using proc
+# The same above can be done using proc
 
 def do_math_operation(amount, proc)
   block.call(amount) # yield won't work!
@@ -19,41 +21,41 @@ def do_math_operation(amount, proc)
   n * 2
 end
 
-result = do_math_operation(5,multiply_by_2)
+result = do_math_operation(5, multiply_by_2)
  => 10
 
-# the same above can be done using lambda
+# The same above can be done using lambda
 def do_math_operation(amount, lambda)
   block.call(amount) # yield won't work!
 end
 
 multiply_by_2 = lambda{ |n| n * 2 }
-result = do_math_operation(5,multiply_by_2)
+result = do_math_operation(5, multiply_by_2)
  => 10
 
 # Differences between Lambda and Procs
-1- Lambda checks for number of parameters , throw an expection if less or more parameters were passed
-ex:
+# 1- Lambda checks for number of parameters , throw an exception if less or more parameters were passed
+# ex:
 lambda = lambda{ |str1, str2| "#{str1}, #{str2}"}
-lambda.call("str1","str2")
+lambda.call('str1', 'str2')
 => str1, str2
-lambda.call("str2","str2","str3")
+lambda.call('str2','str2','str3')
 ArgumentError: wrong number of arguments (3 for 2)
 
 proc = Proc.new{ |str1, str2| "#{str1}, #{str2}" }
 proc.call("str1")
 => str1, 
 
-2- Lambda in a method will return the value to the method and the method continues normally, while Proc stops method execution
+# 2- Lambda in a method will return the value to the method and the method continues normally, while Proc stops method execution
 
 def proc_return
-  Proc.new{|n| puts n}
-  puts "see me if you can"
+  Proc.new{ |n| puts n }
+  puts 'see me if you can'
 end
 
 def lambda_return
-  lambda{|n| puts n}
-  puts "hi, i am here"
+  lambda{ |n| puts n }
+  puts 'hi, i am here'
 end
 
 proc_return
@@ -63,7 +65,7 @@ def lambda_return
 
 # Note proc can't have a return in it , while lambda can
 
-# Using method objects
+# The same can be done using method objects
 def do_math_operation(amount, method)
   block.call(amount) # yield won't work!
 end
@@ -72,7 +74,7 @@ def multiply_by_2(n)
   n * 2
 end
 
-result = do_math_operation(5,method(:multiply_by_2))
+result = do_math_operation(5, method(:multiply_by_2))
  => 10
 
 # Method objects will act like lambda , only lambda is anonymous
diff --git a/procs_lambdas_blocks.rb → clojure.rb b/procs_lambdas_blocks.rb → clojure.rb
diff --git a/service.rb b/service.rb
@@ -9,7 +9,7 @@ class UserCSVDump < Struct.new(:users)
   def csv
     CSV.generate do |csv|
       csv << %w[id username email]
-      @users.each do |user|
+      users.each do |user|
         csv << [user.id, user.username, user.email]
       end
     end

diff --git a/validation.rb b/validation.rb
@@ -1,4 +1,4 @@
-# Not good
+s# Not good
 class User < ActiveRecord::Base
   validates :appropriate_content
 

diff --git a/method_calling.rb b/method_calling.rb
@@ -1,6 +0,0 @@
-# If the last parameter in a method definition is prefixed with an ampersand, any associated block is converted to a Proc object, # and that object is assigned to the parameter. It must be the last argument in the parameter list
-def do_math_operation(amount, &block)
-  block.call(amount)
-end
-
-result = do_math_operation(5) {|amount| amount * 2} => 10

diff --git a/procs_lambdas_blocks.rb b/procs_lambdas_blocks.rb
@@ -0,0 +1,78 @@
+# If the last parameter in a method definition is prefixed with an ampersand, any associated block is converted to a Proc object, # and that object is assigned to the parameter. It must be the last argument in the parameter list
+def do_math_operation(amount, &block)
+  block.call(amount) # OR yield(amount)
+end
+
+result = do_math_operation(5) {|amount| amount * 2}
+ => 10
+
+# a proc is a reusable object oriented block , a block is a proc that can't be saved
+block.class => Proc
+
+# the same above can be done using proc
+
+def do_math_operation(amount, proc)
+  block.call(amount) # yield won't work!
+end
+
+multiply_by_2 = Proc.new do |n|
+  n * 2
+end
+
+result = do_math_operation(5,multiply_by_2)
+ => 10
+
+# the same above can be done using lambda
+def do_math_operation(amount, lambda)
+  block.call(amount) # yield won't work!
+end
+
+multiply_by_2 = lambda{ |n| n * 2 }
+result = do_math_operation(5,multiply_by_2)
+ => 10
+
+# Differences between Lambda and Procs
+1- Lambda checks for number of parameters , throw an expection if less or more parameters were passed
+ex:
+lambda = lambda{ |str1, str2| "#{str1}, #{str2}"}
+lambda.call("str1","str2")
+=> str1, str2
+lambda.call("str2","str2","str3")
+ArgumentError: wrong number of arguments (3 for 2)
+
+proc = Proc.new{ |str1, str2| "#{str1}, #{str2}" }
+proc.call("str1")
+=> str1, 
+
+2- Lambda in a method will return the value to the method and the method continues normally, while Proc stops method execution
+
+def proc_return
+  Proc.new{|n| puts n}
+  puts "see me if you can"
+end
+
+def lambda_return
+  lambda{|n| puts n}
+  puts "hi, i am here"
+end
+
+proc_return
+=> Proc
+lambda_return
+=> hi, i am here
+
+# Note proc can't have a return in it , while lambda can
+
+# Using method objects
+def do_math_operation(amount, method)
+  block.call(amount) # yield won't work!
+end
+
+def multiply_by_2(n)
+  n * 2
+end
+
+result = do_math_operation(5,method(:multiply_by_2))
+ => 10
+
+# Method objects will act like lambda , only lambda is anonymous
diff --git a/service.rb b/service.rb
@@ -1,4 +1,4 @@
-# User service object when:
+v# User service object when:
 # 1- The action is complex
 # 2- The action reaches across multiple models (e.g. an e-commerce purchase using Order, CreditCard and Customer objects)
 # 3- The action interacts with an external service (e.g. posting to social networks)

diff --git a/model_validation.rb → validation.rb b/model_validation.rb → validation.rb
diff --git a/method_calling.rb b/method_calling.rb
@@ -0,0 +1,6 @@
+# If the last parameter in a method definition is prefixed with an ampersand, any associated block is converted to a Proc object, # and that object is assigned to the parameter. It must be the last argument in the parameter list
+def do_math_operation(amount, &block)
+  block.call(amount)
+end
+
+result = do_math_operation(5) {|amount| amount * 2} => 10
diff --git a/scope.rb b/scope.rb
@@ -35,4 +35,19 @@
 # This must be me done using Lambda OR without scopes
 scope :most_updated, -> { where("updated_at > ?", Date.today) }
 
-# Last Note: -> AND lambda are equivalent
+# Note: -> AND lambda are equivalent
+
+# You can define scope dynamically 
+# Example for an api with api_keys
+Status = {:normal => 0, :whitelisted => 1, :blacklisted => 2}
+Status.each_pair do |k,v|
+  scope "status_#{k}", where(:status => v)  # ApiKey.status_whitelisted,...
+
+  define_singleton_method "status_#{k}?" do |st|  # ApiKey.status_whitelisted?(status),...
+    v == st
+  end
+
+  define_method "status_#{k}?" do # api_key.status_whitelisted?,...
+    self.status == v
+  end
+end
diff --git a/meta_tags.rb b/meta_tags.rb
@@ -1,7 +1,45 @@
-# It is common in any rails application to have some meta tags in your HTML as title, description, ...
+# It is common in any rails application to have some meta tags in your HTML as title, description, keywords , fb meta tags,...
 
 # BAD
+# in app/views/layouts/application.html.erb
+<meta name="description" content="<%= @description%>" />
+<meta property="og:image" content="<%= @image_url %>" />
+# in each controller
+@description = 
+@image_url =
 
-# Better
+# Better but bad
+# in app/views/layouts/application.html.erb
+<meta name="description" content="<%= yield(:description) %>" />
+<meta property="og:image" content="<%= yield(:image_url) %>" />
+# In each view
+content_for(:title, @product.title)
+content_for(:title, @product.description)
 
-# Best
+# Best
+
+def og_tags(*tags)
+  content = tags.reduce({}) do |result, set|
+    result.merge! set
+  end
+
+  raw(content.map do |key, value|
+    tag :meta, content: value, property: "og:#{key}"
+  end.join("\n"))
+end
+
+# Then a helper method that pulls standard attrs (name, desc, image, ...) from a piece of content:
+
+def standard_og_stuff(content)
+  {:title => content.name,
+   :description => content.description
+  }
+end
+Then combine in view:
+
+<%=
+  og_tags(standard_og_stuff(@product), {
+    :type => 'video.tv_show',
+    :other_tag => 'something'
+  })
+%>
diff --git a/meta_tags.rb b/meta_tags.rb
@@ -0,0 +1,7 @@
+# It is common in any rails application to have some meta tags in your HTML as title, description, ...
+
+# BAD
+
+# Better
+
+# Best
diff --git a/presenter.rb b/presenter.rb
@@ -4,11 +4,13 @@
 
 # An example of a presenter used to remove logic from view(this is a small example , views can get it even more bloated with logic)
 # app/views/categories/index.html
-<%if @category.image_url%>
-  <%= link_to image_tag("/images/#{category.id}.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
-<%else%>
-  <%= link_to image_tag("/images/default.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
-<%end%>
+<div class="images">
+  <%if @category.image_url%>
+    <%= link_to image_tag("/images/#{category.id}.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
+  <%else%>
+    <%= link_to image_tag("/images/default.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
+  <%end%>
+<div>
 
 # app/presenters/category_presenter.rb
 class CategoryPresenter < BasePresenter
@@ -46,6 +48,9 @@ def method_missing?(*args, &block)
 
 # app/views/category/index.html
 <% present @category do |category_presenter|%>
+<div class="images">
+  <%= category_presenter.featured_image%>
+<div>
 <% end %>
 
 # app/helpers/application_helper.rb

diff --git a/presenter.rb b/presenter.rb
@@ -23,7 +23,7 @@ def top_keywords
 
   def featured_image
     image_path = category.image_url ? category.id : "default"  
-    link_to image_tag("/images/#{image_path}.png") + "some extra text", category_path(@category), :class => 'class-name',     :remote => true %>
+    link_to image_tag("/images/#{image_path}.png") + "some extra text", category_path(@category), :class => 'class-name',     :remote => true
   end
 end
 

diff --git a/presenter.rb b/presenter.rb
@@ -1,12 +1,14 @@
-# Imagine you have a page with lists products in an ecommerce site with side bar containing top discounts in this category,
-# Top brands, top search keywords,...
-# probably your action will look like this:
+# Presenters are created by Controllers/Views and know the current state of the view and the model
+# Can be used to filter away out of tangled logic in the view
+# Also can be used to skin the controller
 
-
-# GOOD
-def show
- present(:category).to_json
-end
+# An example of a presenter used to remove logic from view(this is a small example , views can get it even more bloated with logic)
+# app/views/categories/index.html
+<%if @category.image_url%>
+  <%= link_to image_tag("/images/#{category.id}.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
+<%else%>
+  <%= link_to image_tag("/images/default.png") + "some extra text", category_path(@category), :class => 'class-name', :remote => true %>
+<%end%>
 
 # app/presenters/category_presenter.rb
 class CategoryPresenter < BasePresenter
@@ -20,7 +22,8 @@ def top_keywords
   end
 
   def featured_image
-    link_to_if category.image_url, image_tag("images/#{category.id}", class: "cat-featured-image")
+    image_path = category.image_url ? category.id : "default"  
+    link_to image_tag("/images/#{image_path}.png") + "some extra text", category_path(@category), :class => 'class-name',     :remote => true %>
   end
 end
 

diff --git a/presenter.rb b/presenter.rb
@@ -2,19 +2,9 @@
 # Top brands, top search keywords,...
 # probably your action will look like this:
 
-# BAD
-def index
- @products = 
- @top_brands = 
- @discounts = 
- @top_keywords = 
- ........
-end
-
-# Use Presenters
 
 # GOOD
-def index
+def show
  present(:category).to_json
 end
 

diff --git a/presenter.rb b/presenter.rb
@@ -1 +1,72 @@
-# Content
+# Imagine you have a page with lists products in an ecommerce site with side bar containing top discounts in this category,
+# Top brands, top search keywords,...
+# probably your action will look like this:
+
+# BAD
+def index
+ @products = 
+ @top_brands = 
+ @discounts = 
+ @top_keywords = 
+ ........
+end
+
+# Use Presenters
+
+# GOOD
+def index
+ present(:category).to_json
+end
+
+# app/presenters/category_presenter.rb
+class CategoryPresenter < BasePresenter
+  presents :category
+  def top_brands
+    @top_brands ||= category.top_brands
+  end
+
+  def top_keywords
+    @top_keywords ||= category.top_keywords
+  end
+
+  def featured_image
+    link_to_if category.image_url, image_tag("images/#{category.id}", class: "cat-featured-image")
+  end
+end
+
+class BasePresenter
+  def initialize(object, template)
+    @object = object
+    @template = template
+  end
+
+  def self.presents(name)
+   define_method(name) do
+     @object
+   end
+  end
+
+  def method_missing?(*args, &block)
+    @template.send(*args, &block)
+  end
+end
+
+# app/views/category/index.html
+<% present @category do |category_presenter|%>
+<% end %>
+
+# app/helpers/application_helper.rb
+def present(object, klass = nil)
+ klass ||= "#{object.class}Presenter".constantize
+ presenter = object.new(object, self)
+ yield presenter if block_given?
+ presenter
+end
+  
+# To access presenters from controller
+# app/controllers/application_controller.rb
+private
+ def present(object, klass = nil)
+   klass ||= "#{object.class}Presenter".constantize
+   klass.new(view_context, object)
+ end
diff --git a/presenter.rb b/presenter.rb
@@ -0,0 +1 @@
+# Content
diff --git a/concern_module.rb b/concern_module.rb
@@ -19,6 +19,8 @@ def to_csv(options = {})
 # app/models/user.rb
 include CsvConversion
 
+
+
 # Using modules/plugins
 # in lib/plugins/sponsorable.rb
 module Sponsorable
@@ -28,6 +30,7 @@ def acts_as_sponsorable(configuration = {})
       # do your logic and define the needed associations ex: product has many sponsors,
       # a sponsor may sponsor many products , yes a polymorphic association
     end
+    # if you forgot this line all instances of ActiveRecord::Base will have these methods !
     include InstanceMethods
   end