Merge branch 'master' of github.com:jerryshen/hansay.com

_posts/2011-11-30-using-nested-form-with-simple-form.md

@@ -2,7 +2,7 @@
 layout: post
 title: Using Nested Form with Simple Form
 categories:
-- Rais Plugins
+- Rails Plugins
 ---
 
 I would like to introduce you guys a Rails gem for conveniently manage multiple nested models in a single form.

_posts/2011-12-21-method-missing-best-practice.md

@@ -0,0 +1,79 @@
+---
+layout: post
+title: Method Missing Best Practice
+categories:
+- rails
+---
+
+Method missing allows access to the object attributes, which are held in the @attributes hash, as though they were first-class methods.
+
+If you call a method that doesn’t exist, Ruby will call the method_missing method, and pass the name of the method and any arguments you supplied, which means you can dynamically handle the method.
+
+Here we go, for example, we have a messages table:
+
+{% highlight ruby %}
+
+    create_table "messages", :force => true do |t|
+      t.text     "content"
+      t.boolean  "is_read",     :default => false
+      t.boolean  "is_archived", :default => false
+      t.integer  "post_id"
+      t.integer  "user_id"
+      t.datetime "created_at"
+      t.datetime "updated_at"
+    end
+
+{% endhighlight %}
+
+As a general way, many people will define some following methods
+
+{% highlight ruby %}
+
+    class Message < ActiveRecord::Base
+      
+      def is_read?
+        !!is_read
+      end
+      
+      def is_archived?
+        !!is_archived
+      end
+      
+      def mark_as_read!
+        update_attribute(:is_read, true)
+      end
+      
+      def mark_as_unread!
+        update_attribute(:is_read, false)
+      end
+      
+      def mark_as_archived!
+        update_attribute(:is_archived, true)
+      end
+      
+      def mark_as_unarchived!
+        update_attributes(:is_archived, false)
+      end
+      
+    end
+
+{% endhighlight %}
+
+Wow, this makes your code ugly, we can use `method missing` instead of these all methods
+
+{% highlight ruby %}
+
+    def method_missing(symbol, *args)
+      case symbol
+        when /^is_(un)?(.*)\?/
+          eval "#{$1 ? '!' : '!!'}is_#{$2}"
+        when /^mark_as_(un)?(.*)!/
+          update_attribute :"is_#{$2}", ($1 ? false : true)
+      else
+        super
+      end
+    end
+
+{% endhighlight %}
+
+When you call `is_[string]` method or `mark_as_[string]` method, as you can see, there is definitely no `is_[string]` or `mark_as_[string]` method, yet Rails is smart enough to call the method with the correct parameters, What we have done is to run a regular expression against the name of the method, and if it matches the pattern `is_[string]` or `mark_as_[string]` then it calls the method with the [string] part as the first parameter and the first argument as the second parameter. Pretty powerful, don't you think?