Assigning Value To Variable Within Subscribe Method is not set outside of the subscribe method

Question

How to Access Value Outside Subscribe Method

public ttl_count = 0;
ngOnInit() {
    this.MacService.getAllCouseCount().subscribe((res)=> {
        this.ttl_count = res['count']
    });
}

Whenever I console.log(this.ttl_count) within the subscribe function I get the right result but whenever I log it outside the subscribe function I get 0

Because using `subscribe` makes the code asynchronous. Take a look at [this question](https://stackoverflow.com/questions/42039025/angular-2-value-from-service-not-available-outside-subscribe-function?rq=1). — Korfoo, Apr 30 '19 at 08:19

devDan · Answer 1 · 2019-04-30T08:31:57.797

This is a known question. This is because of all the behavior of observable & subscribe is async, therefore it will have the value just after the subscription. So the functions should be fired after the sub.

public ttl_count=0;

ngOnInit()
{
  this.MacService.getAllCouseCount().subscribe((res)=>
   {
       this.ttl_count=res['count']; // <-- just here it gets the value.
       console.log(this.ttl_count); // <-- it has value, it happend after!

       this.example();
   });
  console.log(this.ttl_count); // <-- no value, it happend before.
}  

public example(): void 
{
    console.log(this.ttl_count); // <-- it has value here.
}

score 1 · Accepted Answer · answered Apr 25 '20 at 05:53

This is because this.MacService.getAllCouseCount().subscribe method is asynchronous and console.log(this.ttl_count) outside subscribe method executes first until you get the response from this.MacService.getAllCouseCount()

you could use async-await or convert this.MacService.getAllCouseCount() this to a promise.

Assigning Value To Variable Within Subscribe Method is not set outside of the subscribe method

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