ExtJS 4.2 Walkthrough — Post-Upgrade Bug

In the last installment, we took a few moments to upgrade our app from ExtJS 4.2.0 to ExtJS 4.2.1. As I pointed out, upgrading is not an insignificant decision, as you will have to test and verify that your app continues to work as expected.

Well, in preparing the next several sections, I came across a bug in 4.2.1 that harms a bit of the functionality I was wanting to implement. While these bugs are a natural (albeit frustrating) part of software evolution, ExtJS is fortunately extensible enough that we can easily create a custom patch (or override) that will allow our code to work as expected WITHOUT modifying the core framework. The benefit of this approach, of course, is that we future-proof our code against new versions. So then, when the new version comes out, we can remove our custom patch and see if the issue is resolved in the core. If it’s not, we can simply re-enable our patch, submit another bug ticket :), and continue on.

Tips for Dealing with Bugs

Before we fix this bug, let me offer a couple suggestions to mentally dealing with bugs in ExtJS:

  • Acceptance: The first step to healthily dealing with bugs in ExtJS is to More >

ExtJS 4.2 Walkthrough – Upgrade!

As with all software, each version of ExtJS ships with the following:

  • Bugs
  • Known issues
  • “Would-be-nice” features that didn’t make the prior release

Fortunately, the ExtJS team is constantly tweaking, fixing, and improving the framework. With each round of development, they’ll do various releases…some major like 4.2, others minor like the recent 4.2.1.

Should I Upgrade?

With each new release, you have an important decision to make: will you continue using the version that you have (which is presumably working), or take a chance and upgrade?

What do I mean by “take a chance”?

With each new version, the full framework is re-released, and the upgrade you’ll make is total (unless you hack new changes into your existing version, which is definitely not advised…). While 99% of the changes won’t affect you whatsoever, there may be bug fixes, improvements, or just complete refactorings that will affect your app in some way. Obviously, the Sencha team does the best they can to mitigate these issues, but they happen nevertheless.

So if you are thinking about taking the plunge of upgrading, ask yourself a few questions first:

  1. Do I NEED to upgrade? Before you upgrade, view the release notes. These will outline all the bug fixes, enhancements, etc. that are included in the More >

ExtJS 4.2 Walkthrough – Documentation

This is a bit of an aside, but tonight I worked on migrating my current progress on this walkthrough app into JSDuck-style documentation. It turned out awesome!

Check out the documentation site here: http://existdissolve.github.io/CarTracker/

I’ll be updating this with each installment, and one of these days I’ll add a walkthrough for how to create this (even though it’s dead simple).

Anyway, super stoked about how awesome they turned out, so I thought I’d share

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ExtJS 4.2 Walkthrough – Part 3: Under Control(ler)

Yep, I lied. In the last post, I said we were going to start making data models and whatnot. All lies. We could, of course, plow ahead with making a data model. However, our app is not quite ready to support a data model of any kind, so we’d make it and have to set it aside until later. Instead of doing that, let’s just wait to make it until later and spend our time on something that will get us closer to being able to use it. Good? Excellent.

NOTE: Code for this installment can be found on GitHub.

A Bit About Controllers

Controllers within ExtJS 4 MVC apps are the brains of your application, the place where the vast majority of your application’s functionality and logic will (and should be) stored. By design, ExtJS 4 is event driven, so your controllers are really like souped up event listeners.

Pretty much every component (views) and data object (stores, models) will fire off a number of events based on the context. So for example, when your store makes an AJAX request via a server proxy, the store (via the proxy) will fire a load event. In your controller (and elsewhere), you can listen to this event and More >


ExtJS 4.2 Walkthrough – Part 1: Setup

Welcome to the first installment in our series on developing an MVC-style ExtJS 4.2 app!

As mentioned in the Introduction, the app we’ll be developing will be a simple management system for a car dealership. The name of the app is so super-creative it will blow your mind. Are you ready for this?

The name of the app is: Car Tracker

Car Tracker?

Yes, Car Tracker.

That just changed your life forever…you’re welcome

NOTE: Code for this session can be found on GitHub.

Getting Started

The first step to creating our app is, of course, to make sure that we have the framework, as well as Sencha Cmd, which we’ll use to generate, theme, and compile the app.

Step 1: Extract SDK

Once you’ve downloaded the 4.2.0 SDK, extract the files. I like to put the SDK in a common location. On my Mac, I put mine here:


Ultimately, it doesn’t matter where you put it, as long as you can find it later.

Step 2: Install Sencha Cmd

Once you’ve downloaded Sencha Cmd, More >


New Project: ExtJS 4.2 App Walkthrough

Over the last few months, I’ve been building (and reading about building) a number of applications using the excellent ExtJS 4.2.0. I thought it might be fun/instructive to do something of a short “walkthrough” of the process of building an app…so that’s what I’m going to do :).

In the next series of posts, I’m going to build an MVC-style ExtJS 4.2.0 app, walking through the code and strategy at each step along the way. I hope that it will be entertaining/instructive to code along with me.

The App

The app is not going to be complicated, but I am going to try to hit some major areas of functionality that are common to developing ExtJS 4 apps. While I can’t promise that every bit of functionality will “fit” your real app’s specific needs, I do promise to avoid ridiculous, over-simplistic and unrealistic examples. My intention is to share my experiences from building real apps, not to teach you about every possible aspect of the ExtJS 4 library, regardless of how relevant it may or may not be to what we’re building. Besides, I don’t know every possible aspect of the library anyway, so I would be of less-than-complete help in that More >