Code license:	MIT License
Labels:	Rails, Ruby, Gears, offline

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GearsOnRailsAPI

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Groups:	Gears on Rails Discussion

People details

Project owners:
	rui.ma15, michael.marcus, mschidlowsky
Project committers:
	bilal.nasir, kaankit

This project plugs Google Gears in Ruby on Rails.

Gears on Rails helps developers to write fully offline functionnal web applications based on Gears without learning a bit of Gears.

Here we provide an demo to show what we have got and illustrate our ideas.

In this page, I am going to show how to make an offline read-only application using GoR Plugin.

In order to use this Plugin, Json should be installed on the system.

     gem install json_pure

We need Goolge Gears also installed on your system. You would be prompted to install Google Gears when you first time vist this web application if you havn't install it.

Now I am playing as a Rails programmer, who wants to make an offline version web app but without how to do this in javascript and havn't heard of Google Gears.

1. Setup a Rails project and Install Plugin

     rails demo
     ruby script/plugin install http://gearsonrails.googlecode.com/svn/trunk/acts_as_local/

1.1 Config the database.yml properly

2. Generate Controller and Edit View

script/generate controller say hello

In hello.html.erb in the View folder.

     <html>
          <head>
          <%= javascript_include_tag 'prototype' %>
          </head>
          <body>
          <h1>Online Status: <%= online_status_tag %> <BR> </h1>
          <b>Gears Status: <%= gears_status_tag %></b>
               <table>
               <tr>
                    <td>&lt;%= link_to_local "SaySomething", :update=>'result', :action=>'saysomething'%></td>
               </tr>
               <tr>
                    <td>Rui says:</td>
                    <td id="result"></td>
               </tr>
               </table>
          </body>
     </html>

Notes: In order to use 'online_status_tag' and 'link_to_local' helpers, you must add <%= javascript_include_tag 'prototype' %> in <head>.

You can add online_status_tag multiple times to the places you need. gears_status_tag is used to indicate the current offline app status.

3. Edit Controller and add local controller

In app/controller/say_controller.rb add

     acts_as_local

then add action 'saysomething'

  def saysomething
    render :text=>Time.now
  end

In app/controller, make subfolder 'local' and add file 'say_controller.json'

Note that all offline actions in 'say' controller are stored in this file in valid json format as "action_name":"code"

Add saysomething offline version in say_controller.json

     {
     "saysomething": "return ('blabla...');"	
     }

4. Done! Start Server

visit: http://localhost:3000/say/hello

The default offline view is the static page of each view. However, once you define the corresponding local action in json file, the offline response would be the return value of that local action. If you either don't want stale pages of your views or write javascript actions, you could simply write like this:

     acts_as_local :except=>['hello']

Visitors can't vist these excluded pages when they are offline.

You can exclude more actions like

     acts_as_local :except=>['hello','aaa','bbb']

Not working?

Change TARGET in vendor/plugins/acts_as_local/lib/gor/javascripts/data_switch.js to your host

The following will show how to create an offline view of a message board application.

Quick Start for Message Board

Use the 4 easy steps to convert your web-application to an offline working web-application.

def new_local
	'
		 posts = Post.find_local("all");
	'
end

1.3)

Define create_local action. It is important to include the single inverted comma '. Add the following code to the controller.

 def create_local
	'
        post = Post.build(params("post"));
         Post.create_local(post);
        window.location.reload( false );
        '
   end

Step 2 - Debug Information

Edit view to create offline view.

Add debug info to online view

<p><b> Debug info: Online: <%= online_status_tag %> 
 Gears: <%= gears_status_tag%> </b></p>

Create a new html.erb file and copy the contents from the online view as it is to make the offline template.

Step 3.Edit View to create offline view.

After offline view is created replace following Ruby functional part

<% for post in @posts %>
    <tr>
      <td><%=h post.title %></td>
      <td><%=h post.body %></td>
    </tr>
  <% end %>

 <%= local '
   var posts;
 posts.each(function(post) {
 puts "<tr>"
 puts "<td>"+post.title+"</td>"
 puts "<td>"+post.body+"</td>"
 puts "</tr>"
 });
' %>

At the end replace

<form action="/posts/new" onSubmit="alert(Form.serialize(this));" class="new_post" id="new_post" >

<% form_local_for('post',:action=>'create') do |f| %>

1. Setup a Rails project and Install Plugin

2. Generate Controller and Edit View

3. Edit Controller and add local controller

4. Done! Start Server

Quick Start for Message Board

Step 0 - Installation of GoR Plugin.

Step1 - Create offline actions by editing the controller

1.1)

1.2)

1.3)

Step 2 - Debug Information

Step 3.Edit View to create offline view.