intro to emberjs

Introduction To

Desert Code CampOctober 18, 2014

Josh Padnick

You want to build the next great app.

Most of today’s apps use the same paradigm.

RESTful API

Web Client Mobile Client Tablet Client

The app exposes a RESTful API. Then we can implement many

potential clients against that API.

So what technologies should we use?

RESTful API

For today’s talk, the APIcan be a black box.

For Ember, it doesn’t even have to be RESTful, but

we prefer that it is.

Mobile Client

Tablet ClientWe could build native apps.

But an HTML5 / CSS3 / JS web app will work, too.

Web Client

For our web client, we have a

few choices.

When does it make sense to choose Ember?

Ember works great if:

• You want to build a “desktop-app-like experience” in the browser

• You’re dealing with moderate - high complexity in your app.

• You want architectural guidance for the long-term at the cost of a steeper learning curve upfront.

• You’re a javascript geek and want a “powerful framework” at your fingertips (API, great tools) and you don’t mind digging into the framework code base.

If you want to know what I think…

Actually, Ember works great for simple apps, too.

But the question is: If you don’t know Ember already, when does it

make sense to learn it?

Ember may not be worth the learning curve if:

• Building a relatively simple app

• You want to launch in less than 6 weeks from start.

• You are brand new to javascript.

• Ember works great for these use cases if you already know it!

• Otherwise, Angular may be a better fit.

The Ember Learning Curve

Effort to Learn

Prod

uctiv

ity

Hello World

Key Concepts Understood

Time for Ember Data

Easily Justify Your Salary!

Informally based on my experience + 2 colleagues

Week1 Week2 Week3 Week4 Week5 Week6 Week7 Week8 Week9

Discover The Ember Way for yourself…

The Ember vs. Angular debate is ongoing.

Here are some links for viewing at home:

• http://www.benlesh.com/2014/04/embular-part-1-comparing-ember-and.html • http://discuss.emberjs.com/t/why-i-m-leaving-ember/6361 • https://www.quora.com/Client-side-MVC/Is-Angular-js-or-Ember-js-the-better-

choice-for-JavaScript-frameworks

My Goals for Today

1. Get you excited about Ember

2. Give you a mental model that will accelerate your process of learning it.

What We’ll Cover Today

• Brief overview of the Ember ecosystem

• See Ember in action

• Show you the “Ember mental model”

• Discuss The Ember Way™

About MeJosh Padnick

josh.padnick@gmail.com

http://JoshPadnick.com

• About to launch medical appointment reminders product built in Ember. • Trained two engineers on Ember • Earned around 500 Stack Overflow reputation points for Ember answers. • Using Ember for a new startup project. • Professional AWS Consultant & Professional Trainer for EmberJS.

602.432.3789

Special Thanks to the Ember Community!

• I have had 100% of questions asked on StackOverflow and discuss.EmberJS.com answered.

• I especially appreciate the responses of:

Overview

Three Players in the Ember Ecosystem

Ember EmberData

EmberCLI

EmberA framework for building ambitious web applications.

• Helps you easily manage app state

• Handles the boilerplate of building a web app

• Gives you lots of tools to get your job done

Ember EmberData

EmberCLI

Ember DataA library for robustly managing model data in your Ember.js applications.

• Represents models in local browser store

• Read/write with any persistence store (most commonly a RESTful API)

• Kind of like an ORM for Javascript

Ember EmberData

EmberCLI

Ember CLI

The command-line interface for Ember

• Instantly scaffold a new ember project

• CLI-based unit and integration tests

• One-command deployment

• ES6 transpilingEmber Ember

DataEmber

CLI

Let’s See a Real Ember App

Later on, we’ll deal live with Ember code.

Mental Model

How We Go From…

To…http://MyEmberApp.com/cats

http://MyEmberApp.com/cats

Trending Cat Pictures

GET http://MyEmberApp.com/cats

User makes an HTTP GET Request

GET http://MyEmberApp.com/cats

Router(router.js)

Ember looks up /cats in the Ember App’s router.js

GET http://MyEmberApp.com/cats

Router(router.js)

Ember looks up this URL in the Ember App’s router.js

GET http://MyEmberApp.com/cats

Router(router.js)

Ember looks up this URL in the Ember App’s router.js

ECMAscript 6 imports!

ECMAscript 6 export

Tells the Ember router how to handle URL changes (use the browser “history”, use a “#”, etc.)

GET http://MyEmberApp.com/cats

Router(router.js)

Ember looks up this URL in the Ember App’s router.js

Ember uses lines 9 - 11 to map a given URL to a particular “state” in the app.

For now, you can think of “state” as the value of various properties, as well as the “currently active URL.”

Visualizing an Ember Routes File

SOURCE: Ember.js in Action. Chapter 3.3. Joachim Haagen Skeie.

=

GET http://MyEmberApp.com/cats

Router(router.js)

Ember looks up /cats in the Ember App’s router.js

GET http://MyEmberApp.com/cats

Router(router.js)

Ember looks up this URL in the Ember App’s router.js

Ember finds a “cats” route!

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Ember looks for a file corresponding to the cats route. It finds one, it

loads the cats route.

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Ember looks for a file corresponding to the cats route. It finds one, so it

loads the cats route.

If Ember didn’t find a cats route, it would use Convention over Configuration to create one!

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

This shows a common use of the “model hook”. We tell Ember Data here to make an API call to GET /cats

and then we’ll have these cats available for local use as Ember Records.

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

RESTful API

Ember Data makes an HTTP GET request for “all cats”

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

RESTful API

The API responds. Ember Data stores the response locally as cat models.

What’s a model?• A model is a class that defines the properties and

behavior of the data that you present to the user.

• Basically, a javascript object plus some Ember fanciness.

• In Ember, models are defined by extending DS.Model.

• An instance of a model is known as a “record” but it’s still just an instance of a DS.Model

Ember Model Basics• A model’s property can be a literal (as we saw

with all of cat’s properties).

• Or a model’s property can be to another model

’s Take on Ember Models

• Your Ember models are a projection of your API’s models.

• Your Ember models should be the projection of your “real” data model that makes sense for a local user.

• My RDBMS may have a bunch of tables which I JOIN in a query, and I might represent that as a single Ember model.

• Basically, think about how you want your data locally, and model accordingly.

Ember hopes you’ll give it JSON, but really it can handle anything.

• Ember’s default adapter is called the DS.RESTAdapter and is based off of Ruby on Rails conventions.

• I built an API using Play Framework (Java) and it was easy to tweak it to speak Ember.

• If you can’t change the API, Ember provides serializers which let you do custom transforms between the API data that you actually get and the data format that Ember expects.

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

The route sets up the cats controller

Ember Controllers• “Controller” is probably the wrong term.

• It’s really more of a view-model.

• The controller’s job is to decorate the model.

• If there’s a property that’s primarily for the UI, model it in the controller.

Ember Controllers• In a moment, we’re going to render our template.

• When we do, the template will look to the controller to see what model is associated with this route.

• You could either have a single model (e.g. one cat) or an array of models (e.g. many cats) associated with the route’s model.

• Single cat —> Ember.ObjectController

• Many cats —> Ember.ArrayController

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

The route sets up the cats ArrayController

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

The route sets up the cats ArrayController

If Ember didn’t find a cats controller, it would use CoC to create one!

This property only makes sense in the UI. We wouldn’t store this in a database.

This is known as a computed property. It updates when any property in the property() method changes.

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

Cats View(e.g. /views/cats.js)

The route sets up the cats view.

Ember Views• Ember views render a Handlebars template and

insert it into the DOM.

• I do occasionally use views to handle basic jQuery

• But you’ll be surprised how rarely you use them.

• That’s why I show the view in gray. You should be surprised that you’re using it.

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

Cats View(e.g. /views/cats.js)

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

Cats View(e.g. /views/cats.js)

The view renders the cats Handlebars Template

Cats Template(e.g. /templates/cats.js)

Ember Templates• Ember uses Handlebars to render templates.

• Ember embraces the “logicless templates” paradigm, perhaps to a fault.

• Templates are easy to learn, so I won’t spend much time on them, but here’s a quick example.

I want to show pictures of cats, so let’s add a pictureUrl property to the cat model.

For demo purposes only, we’re going to fudge the

model in our route

And finally here’s our Handlebars template.

And now the cats themselves!

To summarize, here’s the flow we saw…

GET http://MyEmberApp.com/cats

Router(router.js)

Cats Route(e.g. /routes/cats.js)

Cats Controller(e.g. /controllers/cats.js)

Cats View(e.g. /views/cats.js)

Cats Template(e.g. /templates/cats.js)

What We Didn’t Cover

Here’s the Ember universe of concepts.

• Templates

• Components

• Views

• Naming Conventions (Resolver)

• Ember Objects

• Helpers

• Routes

• Router

• Controllers

• Models

• Testing

• Ember Data

• Local Store

• Initializers

• Dependency Injection / Container

• Run loop

• Promises

• Adapters

• Serializers

• Mixins

And here’s what we covered today…

• Templates

• Components

• Views

• Naming Conventions (Resolver)

• Ember Objects

• Helpers

• Routes

• Router

• Controllers

• Models

• Testing

• Ember Data

• Local Store (indirectly)

• Initializers

• Dependency Injection / Container

• Run loop

• Promises

• Adapters (briefly)

• Serializers (briefly)

• Mixins

Those other concepts will be part of your learning curve.

Ember makes extensive use of promises. Once you understand them, they’re a

pleasure, but until you do, things can feel hard.

So spend time really getting familiar with them.

The Ember Way™

Ember is an opinionated framework. That means that it

wants you to use a certain architecture.

The various ways in which you embrace Ember’s underlying

opinions on architecture are known collectively as The Ember Way.

’s Take on The Ember Way

1. It’s not authoritatively outlined anywhere. But be thinking about The Ember Way while you learn.

2. Avoid direct DOM manipulation. Use Ember’s state management instead. This means avoiding jQuery plugins that do DOM manipulation.

3. Leverage Ember’s bindings, computed properties, and observers. Update your templates by updating properties, not the DOM.

4. Ember has lots of async going on, but if you learn each of the event hooks, it won’t bite you.

5. Use your routes to update “model state” and controllers to update “view state”. Try to avoid handling model state in controllers.

Next Steps

• I find the CodeSchool.com EmberJS tutorial among the best. It’s $29/month. Stat here.

• The EmberJS.com Guide is excellent, but only give you “the top 70% of the iceberg”. But use this as your starting point for reference.

• The EmberJS API is indispensable. It’s important you learn how to use it. Also, always know what this refers to so that you can look up available properties in Ember.

Learning Ember

• If you learn this skill, your ability to “fill in the mental model gaps” will be much easier, and your learning curve will shorten dramatically.

• Everything you need is at this outstanding 12 minute video by Robin Ward:http://eviltrout.com/2014/08/16/debugging-ember-js.html

Learn How to Debug Ember!

• If you’re stuck, go to StackOverflow

• If you’re curious about best practices or have a general question, use the Ember Discussion Forum.

Ramping Up on Ember

Here are some great resources for when you’re ready to dig in to the next level:

• http://balinterdi.com/

• http://www.toptal.com/emberjs/a-thorough-guide-to-ember-data

• http://emberwatch.com/

• http://eviltrout.com/

Advanced Ember

Josh Padnickjosh.padnick@gmail.com

http://JoshPadnick.com602.432.3789

Thank you, Now go build something cool!