Cannot set property 'weather' of undefined

Question

Putting Json data in a this.variable but I keep getting the error Uncaught (in promise) TypeError: Cannot set property 'weather' of undefined. Does anyone know how to fix this.

var currentWeather;

function setup() {
  createCanvas(400, 400);
  currentWeather = new CurrentWeather();
  currentWeather.create();
  loadJSON(currentWeather.api, currentWeather.gotData);
}



function draw() {
  background(0);
}

///////////////////////////////////////////////////////////////////

class CurrentWeather{

 create(){
  let url =       'https://api.openweathermap.org/data/2.5/weather?q=';
  let city = 'Manassas';
  let apiKey ='ApiKeyHere';
  let units = '&units=imperial';
  this.api = url + city + apiKey + units;
   this.weather;
 }

 gotData(data){
   this.weather = data;
 }

}

My guess it is scoping issue: `loadJSON(currentWeather.api, currentWeather.gotData.bind(currentWeather));` — epascarello, Apr 24 '19 at 16:56
What happens if you had a constructor() {} in your class? What line is the error? — Quentin C, Apr 24 '19 at 17:00
When I change create() to a constructor I get the same error — BeanieGod, Apr 24 '19 at 17:03
this.weather is a variable that hold the json data from an api — BeanieGod, Apr 24 '19 at 17:13

Kubwimana Adrien · Answer 1 · 2019-04-25T14:57:58.727

0

Try to change this line loadJSON(currentWeather.api, currentWeather.gotData); to

loadJSON(currentWeather.api, currentWeather.gotData.bind(currentWeather));

You are having scoping issues. this is being overridden/lost from your callback methods. In your case this supposed to be the instance of CurrentWeather which you have as currentWeather = new CurrentWeather();. .bind(currentWeather) is used to scope this to a specific function. Also since the currentWeather is defined globally you may need to just use that variable instead of using this in some cases. It's hard to tell where other issues are without the full code.

edited Apr 25 '19 at 14:57

answered Apr 24 '19 at 16:59

Kubwimana Adrien

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Perhaps you should add some notes to explain why. – Andy Apr 24 '19 at 17:10
That seems to fix the error but when I try to call the variable from anywhere but the gotData function it gives me undefined – BeanieGod Apr 24 '19 at 17:26
@BeanieGod I have updated the answer. – Kubwimana Adrien Apr 25 '19 at 14:58
Sorry about the late response but this was able to fix it thank you – BeanieGod May 03 '19 at 03:23
Great! Your should mark the answer as right answer. @BeanieGod – Kubwimana Adrien May 03 '19 at 04:45

Cannot set property 'weather' of undefined

1 Answers1