How to get the value outside subscribe?

Question

my code

this.service.getName().subscribe((success: any) => {
  if (success) {
    for (let i = 0; i < success[i].length; i++) {
      if (success[i].data.empid== data) {
        this.dataList.push(success[i].name);
      }
    }
  }
});

Unable to access the this.dataList outside subscribe

Most likely relevant: [Why is my variable unaltered after I modify it inside of a function? - Asynchronous code reference](https://stackoverflow.com/q/23667086) — VLAZ, Mar 16 '21 at 11:15
You can't. Any statements that directly depend on `this.dataList` must be inside the subscription. In other words, subscribe where it's response is required. There are ways to cache a result from an observable though. Try googling it. At the end, the data must and _mostly_ will remain asynchronous and reactive. — ruth, Mar 16 '21 at 11:18
Do you display this field in html ? Or do you try to read the value immediately after calling `this.service.getName()` — Arnaud Denoyelle, Mar 16 '21 at 11:19
@ArnaudDenoyelle, need a value immediately after calling the service — sankar, Mar 16 '21 at 11:20
You should simply put the code inside the subscribe, is there a problem with doing that? If so, you should expand on your question. The question as it looks now is identical to countless of other questions on this website — ShamPooSham, Mar 16 '21 at 12:11

score 4 · Answer 1 · answered Mar 16 '21 at 11:25

You try to read this.dataList immediately after the call to this.service.getName() but you have an ordering problem. Consider the following piece of code :

this.service.getName().subscribe(() => console.log('A'));
console.log('B')

This will display B A because the call to this.service.getName() is asynchronous.

What happens is :

Call this.service.getName()
Call console.log('B')
Browser get the response from this.service.getName() and executes () => console.log('A')

Because of that, you try to read this.dataList too soon, when it is still empty or undefined. You should read its value inside the callback :

this.service.getName().subscribe((success: any) => {
  if (success) {
    for (let i = 0; i < success[i].length; i++) {
      if (success[i].data.empid== data) {
        this.dataList.push(success[i].name);
      }
    }

    // Here, you can safely read this.dataList
    [...]
  }
});

How to get the value outside subscribe?

1 Answers1