Updated documentation

Author: subbarao

README.md

@@ -1,19 +1,124 @@
+[official documentation](https://bbgithub.dev.bloomberg.com/pages/InfrastructureExperience/jsonapi_compliable)
+
+### Getting Started
+Please read below documentation related to [jsonapi](http://jsonapi.org/format/#document-resource-objects)
+
+
 ### Adding JSONAPICompliable
 ```
 class ApplicationController < ActionController::Base
   include JSONAPICompliable
 end
+
 ```
-### Define whitelist includes/filters per controller.
+### Define whitelist includes
 ```
-class BooksController < ApplicationController
+class AuthorsController < ApplicationController
   jsonapi do
     includes whitelist: { index: [{ books: :genre }, :state] }
+
+    allow_filter :last_name
+
+    allow_filter :first_name, aliases: [:title], if: :can_filter_first_name?
+
+    allow_filter :first_name_prefix do |scope, filter|
+      scope.where('first_name like ?', "#{filter}%")
+    end
   end
 end
 ```
 Below url requesting state/foo as includes. 
 But foo include is ignored as it is not whitelist. 
+>authors?include=state,foo
+
+### Defining filter field 
+
 ```
-/books?include=state%2Cfoo
+class AuthorsController < ApplicationController
+  jsonapi do
+    allow_filter :last_name
+  end
+end
+```
+will allow us make request as below
+>/authors?filter[first_name]=john
+
+### Defining filter field alias 
+
+```
+class AuthorsController < ApplicationController
+  jsonapi do
+    allow_filter :last_name, aliases: [:name]
+  end
+end
+```
+will allow us make request as below
+>/authors?filter[name]=john
+
+### Adding guard to filter
+
+```
+class AuthorsController < ApplicationController
+  jsonapi do
+    allow_filter :last_name if: :can_filter?
+  end
+
+  def can_filter?
+    true
+  end
+end
+```
+
+### Defining default filter 
+
+```
+class AuthorsController < ApplicationController
+  jsonapi do
+    default_filter :first_name do |scope|
+      scope.where(first_name: 'Willaim')
+    end
+  end
+end
+```
+if no filter provided below request will filter authors first_name='Willaim'
+
+>/authors
+
+### Deserialize requests params which are coming jsonapi format
+
+```
+  class AuthorsController < ApplicationController
+    before_action :deserialize_jsonapi!, only: [:update, :create]
+  end
+```
+incoming parameters
+```
+  {
+    data: {
+      type: 'authors',
+      attributes: {
+        first_name: 'Stephen',
+        last_name: 'King'
+      },
+      relationships: {
+        books: {
+          data: [
+            { type: 'books', attributes: { title: 'The Shining' } }
+          ]
+        }
+      }
+    }
+  }
+```
+will be deserialized to
+```
+  {
+    authors: {
+      first_name: 'Stephen',
+      last_name: 'King'
+      books_attributes: [{
+        title: 'The Shingin'
+      }]
+    }
+  }
 ```