Models

Question 1

How do you set an attribute on a model?

Answer 1

model.set(‘title’);

Question 2

How do you get an attribute on a model?

Answer 2

model.get(‘title’);

Question 3

How do you get a JSON representation of a model?

Answer 3

model.toJSON();

Question 4

How do you clear all attributes on a model?

Answer 4

model.clear();

Question 5

How do you unset an attribute on a model?

Answer 5

model.unset();

Question 6

How do you see if a model has an attribute?

Answer 6

model.has(‘title’);

Question 7

How to create a model?

Answer 7

var Model = Backbone.Model.extend();

Question 8

How do you instantiate a model?

Answer 8

var model = new Model;

Question 9

How do you set values to be a default when coding a model?

Answer 9

var Song = Backbone.Model.extend({
    defaults: {
        title: "default value"
    }
});

Question 10

How do you use validation on model attributes?

Answer 10

• You need to implement the validation method in your model
• validate is called anytime the attributes are initially set.
• Validate
• attrs is a json object representing the models given attributes
• You can check if said attribute is set, etc.
  validate: function(attrs) {
  if (!attrs.title)
  return ‘The song requires a title’;
  }

Question 11

How can you check if a model is valid? Which checks validate

Answer 11

model.isValid() // function returns true || false

Question 12

If you call isValid on a model how do you get the last validation error message?

Answer 12

You call model.validationError on a model after you have called isValid that will be available

Question 13

true or false - You can use inheritance to extend your custom models?

Answer 13

true

Question 14

How do you extend you custom models?

Answer 14

Animal.extend() just like extend Backbone.Model

Question 15

true or false - You cannot override a parent method on an extended class?

Answer 15

false

Question 16

How do you override a parent method in an extend object?

Answer 16

Use the same method name and write new code.

Question 17

How can you call the parent class method from a sub class?

Answer 17

Javascript doesn’t provide an easy way, but you can do…

ClassName.prototype.methodyouwantocall.apply(this)

Question 18

What are the 3 persistence operators a backbone model has?

Answer 18

fetch() - GET
save() - POST/PUT - new POST, update PUT
destroy() - DELETE

Question 19

How does Backbone know if it’s a PUT or a POST?

Answer 19

If it’s been fetched from the server before it’s a PUT, and if it hasn’t before then Backbone thinks it’s a new item and does a POST

Question 20

What property do you use to tell models where to look on the server?

Answer 20

urlRoot: ‘/api/tasks’

Question 21

What property is used to fetch a model from the database?

Answer 21

id: 1 when instantiating the model.
var song = new Song({ id: 1 })
results in /api/songs/1 etc

Question 22

true/false Backbone routes are restful by default?

Answer 22

TRUE

Question 23

how would you do a PUT request to the server?

Answer 23

var song = new Song({ id: 1 });
song.fetch();

song. set(‘Title’: ‘Hello world’);
song. save();

api/songs/1 PUT request;

Question 24

How would you create a new model and persist it?

Answer 24

var song = new Song();

song. set(‘Title’, ‘Hello world’);
song. save();

api/songs POST request persisting a new item.

Question 25

How would you delete a model from the database?

Answer 25

``` var song = new Song({ id: 1 }); song.destroy(); ``` api/songs/1 DELETE request to the server.

Question 26

true/false You can use a custom unique identifier for a model?

Answer 26

TRUE

Question 27

How do you tell Backbone to use a different unique identifier besides 'id' to identify the model?

Answer 27

idAttribute: 'songId' or 'song_id' property and then when getting a model you would use var song = new Song({ songId: 1 });

Question 28

true/false Are all database calls asynchronous and have a success and error callback?

Answer 28

TRUE

Question 29

How do you access the error/success call backs for fetch/destroy?

Answer 29

``` var song = new Song({ id: 1 }); song.fetch({ error: function() {} success: function() {} }); ``` same for song.destroy();

Question 30

How do you access the error/save callbacks on the save method?

Answer 30

``` var song = new Song({ id: 1 }); song.save({}, { error: function() {} success: function() {} }); ``` NOTE: the first argument is a hash of attributes you'd like to update. The second argument is where the error/success callbacks are accessed. Preferably you use song.set({ hash attributes }) and later call .save with an empty hash as the first argument.