Ember Data Internals - Speaker Deck

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Data

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• Core Concepts • Public API • Adapter/Serializer API • Internals

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Why Ember Data?

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Things It‘s Still Hard to Do in 2012 (which is bullshit)

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Creating two records, setting up a relationship between them, then saving them.

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Easily starting with fixture data if your server isn‘t ready yet.

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Changing the JSON representation of your model without changing app code.

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Only loading models you don‘t have cached.

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Keeping the DOM up-to-date with model changes.

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Dynamically switching between a server and offline cache.

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Using awesome new browser features like WebSockets and TypedArrays.

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These problems are SO COMMON!

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Why do we all do it by hand?!

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Convention Over Configuration

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conventional conventional { json: "lol" } WHY IS THIS NOT CONVENTIONAL?!?!

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Ember Data

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Architecture Overview

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Store Adapter Serializer Record Record Record Record

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Store Adapter Serializer Record Record Record Record Server Semantics Application Semantics Things that wouldn't change if your backend changed. I.e., ignoring your server protocol, how would you ideally model your data? How do you think about your models? Things that are specific to your server/backend/ persistence layer.

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Loading a Record

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Store Application App.Post.find(1) Record

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Store Application Person.find([1, 2, 3]) RecordArray

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Store Application Person.find() RecordArray

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// State for '/posts' App.PostsState = Ember.State.extend({ setupControllers: function() { var posts = App.Post.find(); this.set('controller.content', posts); } });

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Store Application App.Post.find(1) Adapter Record loading

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Store Adapter Record loading

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Store Record Adapter Serializer loading

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Store Record Adapter Serializer loaded

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Store Application App.Post.find(1) Record loaded

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Ember Data in Practice

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Setup

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App.Store = DS.Store.extend();

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var attr = DS.attr; App.Post = DS.Model.extend({ title: attr('string'), body: attr('string'), comments: DS.hasMany('App.Comment'), author: DS.belongsTo('App.User') });

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Finding Records

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var person = App.Person.find(1);

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person.get('isLoaded'); //=> false person.get('firstName'); //=> undefined

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wait a bit

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person.get('isLoaded'); //=> true person.get('firstName'); //=> "Tywin"

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Changing Records

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var tyrion = App.Person.find(2); tyrion.get('isDirty'); //=> false tyrion.get('firstName'); //=> "Tyrion" tyrion.set('firstName', "Yollo"); tyrion.get('isDirty'); //=> true

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store.commit(); tyrion.get('isDirty'); //=> true tyrion.get('isSaving'); //=> true

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wait a bit

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tyrion.get('isDirty'); //=> false tyrion.get('isSaving'); //=> false

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Creating Records

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var eddard = App.Person.createRecord({ firstName: "Eddard", lastName: "Stark" }); var robb = App.Person.createRecord({ firstName: "Robb", lastName: "Stark" });

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robb.set('parent', eddard); store.commit();

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Deleting Records

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tywin.deleteRecord();

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Transactions

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var transaction = store.transaction(); transaction.add(tyrion); transaction.add(tywin); transaction.commit();

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transaction.rollback();

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Record States

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Loaded Updated Created Deleted Clean Dirty In-Flight In-Flight Error Error

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var person = App.Person.find(1);

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person.get('isLoaded'); //=> false person.get('firstName'); //=> undefined

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wait a bit

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person.get('isLoaded'); //=> true person.get('firstName'); //=> "Tywin"

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isLoaded isDirty isSaving isDeleted isError isNew isValid These are derived from the current state object, which is awesome!

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• Each record has an associated state manager. • The store does not make changes to records directly. • Instead, events are sent to the record. • The record responds based on its current state.

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Uncaught Error: could not respond to event setProperty in state rootState.loaded.created.inFlight. = You tried to change a record while it was being saved.

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// store.js record.loadedData();

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// model/model.js loadedData: function() { this.send('loadedData'); }

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// model/states.js loading: DS.State.create({ // TRANSITIONS exit: function(manager) { var record = get(manager, 'record'); record.trigger('didLoad'); }, // EVENTS loadedData: function(manager) { didChangeData(manager); manager.transitionTo('loaded'); } })

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Adapters

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• Are relationships saved in the parent or the child? • What payloads are sent to what URLs? • What actions map to what HTTP verbs? • What is the name of the primary key? • What are the names of attributes? • Are objects embedded or referred to by ID? Serializer Adapter

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Serializer JSONSerializer RESTSerializer

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Serializer Transform Values new Date() to "2007-04-05T14:30" (and vice versa)

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DS.JSONSerializer.registerTransform('boolean', { serialize: function(value) { return value ? 'true' : 'false'; }, deserialize: function(value) { return value === 'false' ? false : true; } }); Serializer

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Serializer Add ID addId: function(data, key, id) { data[key] = id; }

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Serializer Add Attributes addAttribute: function(hash, key, value) { hash[key] = value; }

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Serializer Add Belongs-To Relationships addBelongsTo: function(hash, record, key, relationship) { var id = get(record, relationship.key+'.id'); if (!Ember.none(id)) { hash[key] = id; } }

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Serializer Extract Attributes extractAttribute: function(type, hash, attributeName) { var key = this._keyForAttributeName(type, attributeName); return hash[key]; }

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Serializer Declarative Syntax App.Adapter.map('Person', { firstName: { key: 'FIRST_NAME' } });

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Thank you. Questions? http://plus.tomdale.net http://emberjs.com @tomdale