Can't access JSON attribute.

Question

alert(fetch('https://facebook.github.io/react-native/movies.json')  
    .then(function(response) {
        return response.json()['description']
    }))

I was expecting Your app fetched this from a remote endpoint! but apparently, this is just an Object?

According to the other answers I've checked, like this one, this should work perfectly.

Yury Tarabanko · Accepted Answer · 2017-03-30T19:27:55.833

1

response.json returns a Promise

.then(function(response) {
    return response.json()
})
.then(function(data) {
   return data.description
})
.then(function(description) {
    alert(description)
 })

edited Mar 30 '17 at 19:27

answered Mar 30 '17 at 19:20

Yury Tarabanko

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How many open brackets/braces are before this? There are 2 brackets on the 3rd line, but the other `then` statement only 1, for example, and no semi-colon. – User Mar 30 '17 at 19:27
Still better than callback hell. BTW you could use arrow functions if don't care much about old browsers. `fetch(blah).then(x => x.json()).then(data => alert(data.description))` - no brackets at all :) – Yury Tarabanko Mar 30 '17 at 19:27
So there's no way to get the data out of there? I want to save this as a variable and use it elsewhere in my code. – User Mar 30 '17 at 19:35
You can save promise as a variable say `gettingData = fetch().then(x => x.json())` and use it later still knowing it is a Promise `gettingData.then(data => /* do something with data*/)`. Plz read this question to get better understanding of what the problem with async code is about http://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call – Yury Tarabanko Mar 30 '17 at 19:39

score 0 · Answer 2 · answered Mar 31 '17 at 06:48

You can access the description as shown below.

To save the value and use it later, you can use states (aka Component States).

.then(function(response) {
    var resJson = response.json();
    var des = resJson['description'];
    this.setState(
         { 
             description: des 
         }
    )

    }))

You can define your states in the React Component like so:

class MyClass extends Component {

    state = {
        description: ""
    }

And retreive the state like so:

var currentState = this.state.description;

Can't access JSON attribute.

2 Answers2