CODEWITHSUNDEEP
javascriptparse-platform
Vlad Miller
Vlad Miller

Reputation: 2279

Get access to instance attributes inside of instance method

I'm trying to extend a Object and add some custom instance methods to it. How do I access data in attributes?

const Media = Parse.Object.extend('Media', {
  getUrl: function getUrl() {
    // HOW DO I ACCESS ATTRIBUTES HERE?
  },
});

const url = new Media({
  url: 'url here',
}).getUrl()

I basically expected attribute values to live either in this or in this.get('url')

So how do I get access to attributes inside of instance method?

Thanks

Upvotes: 0

Views: 105

Answers (2)

Vlad Miller
Vlad Miller

Reputation: 2279

It turned out that I tried to execute getUrl() method on a nested object, however I didn't included this object in query.

Upvotes: 0

Arkantos
Arkantos

Reputation: 6608

The problem with your code is that you're trying to use a constructor which doesn't initialize your instance. 

const url = new Media({
  url: 'url here',
});

Here you're passing a state object with url property to Media constructor but you are not actually capturing that object to initialize your instance, so the object is simply ignored. Hence there's no property by the name url on your instance and this.url will be undefined.

As documented here, Parse.Object.extend() will return a subclass of Parse.Object for the given class name. The second argument to extend() is an object containing instance properties/methods which are available to all the instances. Once you defined the class, you can create a new instance using the new keyword. If you have several parameters to initialize while creating the instance, you can make use of the initialize method like below.

const Media = Parse.Object.extend('Media', {
  initialize : function(state){
     this.url = state.url;
     this.type = state.type;
  },
  getUrl: function getUrl() {
    return this.url;
  },
  getType : function(){
    return this.type;
  }
});

Then create a instance by calling the constructor new keyword and passing the state object like below

const url = new Media({
  'url' : 'myURL',
  'type' : 'video'
});

url.getType(); // returns 'video'
url.getUrl(); // returns 'myURL'

Upvotes: 1

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