More Rails 2.1 changes that target JSON and therefore Ext JS

Two days ago I posted about Rails 2.1 changes that make living with Ext JS easier. Today I discovered (via Jörg Battermann) a tutorial about using Rails 2.1 (see Part 1 and Part 2).
The tutorial shows two new config options that target JSON, especially the to_json method: ActiveRecord::Base.include_root_in_json and ActiveSupport.use_standard_json_time_format

Here are the respective changesets and some more information on these changes:

Changeset 9202: Tweak ActiveRecord::Base#to_json to include a root value in the returned hash: {post: {title: ...}}

This is almost a nice change. I mean almost because it might help you when feeding your Ext JS forms via a Ext.data.JsonReader, but it'll break your Ext JS grids, when using the Ext.data.JsonReader.

Currently, you do something like the following in your javascript code:

  orders_ds = new Ext.data.Store({
   reader: new Ext.data.JsonReader({root: 'orders', id: 'id' }, orders_items),
   proxy: new Ext.data.HttpProxy({url: orders_path_json})
  });

and the following in your controller action:

render :json => { :orders => @orders }

which returns a JSON data in the following format

{"orders": [{"id": 1, ...}, {"id": 1, ...}]}

Well, after you turn on the ActiveRecord::Base.include_root_in_json option, it'll return:

{"orders": [{"order": {"id": 1, ...}}, {"order": {"id": 2, ...}}]}

which cannot be understood by your Ext.data.JsonReader by default.

It would be smarter if the include_root_in_json would differ between a single active record object and a collection of active record objects.
Therefore, if you use render :json => @orders or @orders.to_json, it would return the data in an array without a root for each object, but with the plural name of the model class name as root for the array. Just as I showed in the first JSON data example.
Well, maybe I'll write a patch for Rails for that.

Changeset 9203: Add config.active_support.use_standard_json_time_format setting so that Times and Dates export to ISO 8601 dates.

If you turn on this config option, it will probably also break your Ext JS grids. But you can easily fix that...

Right now you probably have this code in your record layout part when dealing with dates:

{ name: 'release_date', type: 'date', dateFormat: 'Y/m/d' }

Well, your JsonReader assumes that the date format is Y/m/d. But after you turned the use_standard_json_time_format option on, it will return the date in the default JSON date format.
It means you have to change the date format to the following:

{ name: 'release_date', type: 'date', dateFormat: 'Y-m-d' }

Well, these Rails changes are all JSON related changes that come in the soon to be releases Rails 2.1, but which won't really make your life easier with Ext JS. Sorry to disappoint you on that. But Rails is certainly going into the right direction.

Rails 2.1 changes that make living with Ext JS easier

I just like to point out a few changes of the soon to be released Rails 2.1 which I caught via Chu Yeow's Living on the edge blog series.

Automatically parse posted JSON content for Mime::JSON requests
The most important change is probably the automatically parsing of JSON requests into the params hash.
Here's the example from Chu Yeows's post:

# http request
POST /posts
{"post": {"title": "Breaking News"}}

# controller action code
def create
  @post = Post.create params[:post]
end

Similar functionality is also provided by the json_request plugin which I use currently with Rails 2.0.2.

json_escape for escaping HTML entities in JSON strings
In the same post, Chu Yeow is mentioning the addition of json_escape:

json_escape("is a > 0 & a < 10?")
# => is a \u003E 0 \u0026 a \u003C 10?

# or you can use the alias j in your erb/haml templates:
<%=j @person.to_json %>

Right know I can't think of another use as Chu Yeow's example for documenting a JSON api.

Custom JavaScript and stylesheet symbols
You all know javascript_include_tag :defaults, which includes your application.js and prototype files.
Now you can define your own symbols, such as :extjs.

See here for details of this change.
This addition is similar to my little helper I use in my projects which I described in my ext-all.js or ext-all-debug.js post.

Haml 2.0
By the way, because I mentioned haml, today Haml 2.0 was released, which includes a javascript filter. Check out the blog post for more info.

Rails helpers in Ext JS

Today I needed to truncate a set of strings in Ext JS. Rails has the truncate helper method built in, Ext JS not, which isn't bad since it's pretty easy to write your own little helper in Ext JS.
Update: Diego pointed out that there is actually a truncate method in Ext JS, called ellipsis which can be found in the Ext.util.Format class. I hope this post still makes a little sense, since it's about writing your own helpers in Javascript/Ext JS.

Here's the Ruby code from the Rails core:

def truncate(text, length = 30, truncate_string = "...")
  if text.nil? then return end
  l = length - truncate_string.chars.length
  (text.chars.length > length ? text.chars[0...l] + truncate_string : text).to_s
end

Here's my little Javascript helper:

Ext.apply(String.prototype, {
    
  truncate_length: 30,
    
  truncate_string: "...",
    
  truncate : function(truncate_length, truncate_string) {
    truncate_length = truncate_length || this.truncate_length;
    truncate_string = truncate_string || this.truncate_string;
    var length = truncate_length - truncate_string.length;
    return this.length > truncate_length ? this.substr(0, length) + truncate_string : String(this);
  }

});

It has the same behavior as the Rails helper. Note that you don't really have to use Ext.apply(), but it helps you to DRY your code, since you can pass an object with multiple methods and attributes to the prototype attribute, instead of writing String.prototype = function() { .. } for each attribute/method you want to add/overwrite.

Creating an extra attribute for truncate_length and truncate_string allows you to easily define your default values for your app. So if you like to append only two dots by default, just add String.prototype.truncate_string = '..' to your code.

While writing this post I actually remember that Prototype JS has the truncate and many other helper methods already built in. But well, writing your own helpers (with the help of Ext JS) can be fun, too. X-D

Here is the Prototype code, just for the sake of comparison:

  truncate: function(length, truncation) {
    length = length || 30;
    truncation = truncation === undefined ? '...' : truncation;
    return this.length > length ?
      this.slice(0, length - truncation.length) + truncation : String(this);
  }

Ordered Attributes

I released my first Ruby on Rails plugin today. It is actually helpful for building Ext JS grids! More on that later in an extra post. Below some information about the ordered attributes plugin (taken from the README file).

Ordered Attributes
This Ruby on Rails plugin provides a way to order ActiveRecord attributes for using them for csv exports or automated
table generation.

Installation
git clone git://github.com/steffen/ordered_attributes.git vendor/plugins/ordered_attributes
or if you are on edge rails
script/plugin install git://github.com/steffen/ordered_attributes.git

Example

class Person < ActiveRecord::Base
  
  attr_order :name, :street, :zip, :city
  
  attr_groups :address => [:street, :zip, :city],
              :birth => [:date_of_birth, :place_of_birth], // you can use %w(date_of_birth place_of_birth) as well
              :all => [:name, :address, :birth]
  
end

Use the ordered_attributes method to get the ordered attributes:

Person.ordered_attributes
=> [:name, :street, :zip, :city]

Person.ordered_attributes(:all)
=> [:name, :street, :zip, :city, :date_of_birth, :place_of_birth]

See spec/ordered_attributes_spec.rb for more Examples!

Ext JS 2.1 with (more-or-less) first-class REST support released

In case you missed it, yesterday the Ext JS Team released version 2.1 of it's impressive Javascript library.

Besides nice new widgets such as the slider and statusbar, and big performance improvements, the Ext JS library is now supporting the PUT and DELETE http verbs (besides GET and POST) when using their Ext.form.Action class for Ajax Requests. But is that helping us Rails developers? Not really, since most browsers haven't first-class support for PUT and DELETE (yet). Rails uses a work-around for this problem. If you, for example, create a form tag with the PUT method, it creates an hidden form field with name _method and the http verb as value. Therefore you actually have to add this hidden form field in your Ext form manually and continue using POST as method.

Here is their blog post with all infos about this release and other news (such as a new ext js website with more examples!)

Btw, they also show a preview of Ext JS 3.0, which includes a performance-optimized datagrid view. I recently addressed/solved the performance issues in my PrinterGridPanel class included in my PrinterFriendly extension, which is meant for printing and has therefore less view-features.

Fitting Ext JS into the Rails architecture

When you start building your first Ext JS page into your Rails application, you certainly will wonder where to put the Javascript code.
Instead of just creating a javascript file such as posts_show.js in your public/javascript directory, here is a more elegant way for adding Ext JS pages to your Rails (2.0.2!) project:

# app/controllers/post_controller.rb

def show
  @post = Post.find params[:id]

  respond_to do |format|
    format.html { render :layout => "extjs" } # *
    format.js
  end  
end

# *) special extjs layout which includes the required extjs files,
#    in case you have a different default layout for non-Ext JS pages 


# app/posts/show.html.erb

<%= javascript_include_tag formatted_post_path(@post, :js) %>

# app/posts/show.js.erb

Ext.onReady(function(){
  // your ext js javascript code here
  // because this file is rendered via the erb renderer,
  // you can add ruby code such as:
  alert('<%= @post.title %>');
});

ext-all.js or ext-all-debug.js

To ease the debugging process, the Ext JS package includes the uncompressed javascript files of their library as well.

Here's a small Rails helper to add the Ext JS library files based on your Rails environment:

# app/helpers/application_helper.rb
module ApplicationHelper

  ... # your other helpers here

  def javascript_include_extjs
    if RAILS_ENV == "production"
      javascript_include_tag "ext/adapter/ext/ext-base.js", "ext/ext-all.js"
    else
      javascript_include_tag "ext/source/core/Ext.js", "ext/source/adapter/ext-base.js", "ext/ext-all-debug.js"
    end
  end

end

In your view layout header you just need to call:

<%= javascript_include_extjs %>

Important: Don't forget the ext js css files!

P.S.
You can find some more hints on debugging Ext JS here.

Sending forms the "old way" with Ext JS

The normal non-AJAX life-cycle of sending a form in Rails is the following:

1. The user submits the form
2. The browser is going to the form's action url
3. The Rails action calls some model methods and sends a redirect to the users browser to a overview page or the created record for example

Here are some code snippets to solve this life-cycle with Ext JS and Rails:

// ext js form

var submit_button = new Ext.Button({
 text: "Submit",
 handler: function () {
   form = this.ownerCt.getForm();
   form_as_dom = form.getEl().dom;
   form_as_dom.action = form.url;
   form_as_dom.submit();
 }
})

new Ext.form.FormPanel({
 url: "<%= confirm_order_path(@order)%>",
 standardSubmit: true, // doesn't do anything in ext js version 2.0.2
 items: submit_button
})

# rails controller action

def confirm
 order = Order.find params[:id]
 order.confirm!
 order.save # no error handling in this example

 redirect_to order_path(order)
end

The special thing here is, that Ext JS doesn't really support the old-way of sending form data to the browser. But it's actually on their roadmap for the 2.1 release in this spring, which should be out very soon. The above code shows the current "work around" by using the actually DOM object of the form.

For completion and comparison, here the code for doing a form submit via AJAX.

// ext js form

var submit_button = new Ext.Button({
 text: "Confirm",
 handler: function () {
   form = this.ownerCt.getForm()
   form.submit({
     success: function () {
       this.setText("Unconfirm");
       form.url = "<%= unconfirm_order_path(@order) %>";
     },
     scope: this
   });
 }
})

new Ext.form.FormPanel({
 url: "<%= confirm_order_path(@order)%>",
 standardSubmit: false, // false by default,
 // but doesn't do anything in ext js version 2.0.2
 items: submit_button
})

# rails controller action

def confirm
 order = Order.find params[:id]
 order.confirm!
 order.save # no error handling in this example

 render :text => "{ success: true }" # ext js converts
 # responses to json by default, that means no need
 # to send an explicit json header
end

Discovering Ext JS with Rails

Before I discovered the Ext JS - Javascript Library in November 2007, I was working with Ruby on Rails for almost a year. (I know, pretty late since Rails came already out in 2004, but I was stuck with my PHP Projects.)

From then on, Rails was really helping me to get my models and controllers in order. But what about the view layer? Yes, Rails was helping me here, too. But not as much as on the model and controller level. I like partials, helpers and rjs, but building a nice graphical interface was still a lot of work.

When building graphical interfaces the first thing you need to have is an idea what the user is supposed to do on the interface.

Second, you need to think about the layout and what elements you want to put on the interface (separated in pages or states). In this step, you as an interface developer have so much freedom that you can end up weeks and months moving around elements and pixels on your interface seeking for the best usability and look. Ext JS doesn't really limit your freedom, but it gives you very very helpful guidelines for building nice interfaces, since it has ready-to-use widgets such as grids, panels, buttons, menus and toolbars which can be configured via options to your need. Ext JS is for the client-side of web applications as Ruby on Rails is for the server-side of web applications.

Third, you have to design the interface elements on yourself or by a designer. Ext JS includes nice GUI elements or so-called widgets out-of-the-box. Some may argue the Ext JS theme is very "Windows Vista"-like, but it's gives you at least a beautiful interface right at the beginning which can be customized by you without limits.

Forth, you need to build the interface. Building the interface can be tricky, especially today when everybody is expecting some fancy AJAX, which can be very useful in a lot of cases. Now the fight with Javascript, CSS, ERB, controller actions and cross-browser compatibility is starting. The Rails built-in javascript libraries Prototype and script.aculo.us or additional template engines like Haml or Markaby can help you with this step, but it's still not less complicated.
With Ext JS, you have everything in one library which has a very clean API and documentation. You actually have to use actually HTML or Haml very few times, since you can build the whole interface by Ext JS widgets and layouts which are configured by options in the JSON-Format.

Therefore, the best solution and more and less silver bullet for building web-based user interfaces is for me Ext JS.

I'm starting this blog to document some hints and tipps on using Ext JS together with Ruby on Rails. But this blog is not supposed to be an one-way street. Through this blog I hope to meet other Rails developers that use Ext JS and have their own solutions and tipps. I welcome everybody to use the comments feature or send me an email to s dot hiller at caprireleases dot com.