How to return the result of this function

Ionic Framework ionic-v3
1

hello please help me I have a problem with this function I would like him to return the result of the search in the database my results are always wrong.

    test(value) {
        var res;
        this.storage.get('age').then((currencies) => {
            this.getCurrentCurrency().then((val) => {
                res = value * currencies[val]['rate'];
                
            });
        });
        return res;
    }

Thanks. I want to return res

2

Hi, @durvilchat

What is the result could you print here:

thanks

3

Hi @addwebsolution
res = value * currencies[val][‘rate’];

4

means what is res ?

I mean what is wrong result ?

5

Hi @durvilchat

try below code :

test(value) {
        var res;
        this.storage.get('age').then((currencies) => {
            this.getCurrentCurrency().then((val) => {
                res = value * currencies[val]['rate'];
                return res;
            });
        });
    }
6

res because he returned before the end of this operation

7

hello please help me I have a problem with this function I would like him to return the result of the search in the database my results are always wrong.

test(value) {
    var res;
    this.storage.get('age').then((currencies) => {
        this.getCurrentCurrency().then((val) => {
            res = value * currencies[val]['rate'];
            
        });
    });
    return res;
}

Thanks. I want to return res

8

Hello,

have you tried @addwebsolution code?

Take a look where return is. In your case return is in syncronous part, he’s case is return in asyncronous part.

And nothing has changed?

Best regards, anna-liebt.

9

@addwebsolution please are you have a solution ??

10

Let me know you should try my above code

11

@addwebsolution
What code ?

12

this code i was tell you…

13

@addwebsolution this code return undefined value

here the console.log(test(250)) return undefined value

14

try below code :


test(value): :Promise<any> {
      return new Promise(resolve => {
          this.storage.get('age').then((currencies) => {
              this.getCurrentCurrency().then((val) => {
                let res = value * currencies[val]['rate'];
                  resolve(res);
              });
          });
     });
    }
1 Like
15

You have to return a Promise, but there is no need to create a new one:

  test(value: number): Promise<number> {
    return this.storage.get('age').then((currencies) => {
      this.getCurrentCurrency().then((val) => {
        let res = value * currencies[val]['rate'];
        return res;
      });
    });
  }

  useTest() {
    this.test(5).then((res) => {
      console.log(res);
    });
  }
16

@addwebsolution your code turns the results of this type

t {__zone_symbol__state: null, __zone_symbol__value: Array(0)}
__zone_symbol__state
:
true
__zone_symbol__value
:
14.869259999999999
__proto__
:
Object
17

@pwespi this code return undefined value

18

hello,

are you sure that the other parts like getCurrentCurrency() deliver valid results?

Best regards, anna-liebt

19

Yes yes

My problem is to return the value of res

20

You’re nesting Promises. Don’t. You are doing
Promise.then(_ => promise.then(_ => promise))
Instead do

Promise.then(_ => promise)
      .then(_ => promise)
    .then(_ => promise)

Chain them one after the other. Don’t put them inside one another.