从一个ts到另一个ts的角返回值

Question

In my angular project, I have two ts files as below:

Data.ts

import { Injectable } from '@angular/core';
import { MyStorage } from '../storage';

@Injectable()
export class itemFromStorage {
constructor(public storage: Storage) {  

}

    GetItemDataFromStorage(current){        
        this.storage.get(current).then((val) => {
          return val;  //????    
        }); 
   };    

}

Main.ts

import { itemFromStorage } from '../data'

export class item_thumb {
    constructor(public itemStorage: itemFromStorage) { 

    };  

   fetchThumbData(){
     var data = this.itemStorage.GetItemDataFromStorage(this.dataNumber);
     console.log(data);//????
   }
}

From the data.ts , how do I return the data value to main.ts ?

Answer 1

your data.ts method should return only the request itself, without subscribing to it:

    GetItemDataFromStorage(current){        
        return this.storage.get(current);
   }; 

and in your main.ts method subscribe and receive the data:

   fetchThumbData(){
     var data = this.itemStorage.GetItemDataFromStorage(this.dataNumber).then((data) => {
          console.log(data);//???? 
        }); 

   }

Answer 2

Most likely your Data.ts is returning a promise.
Main.ts

export class item_thumb {
    constructor(public itemStorage: itemFromStorage) { 
    };  
   fetchThumbData(){
     let promise = this.itemStorage.GetItemDataFromStorage(this.dataNumber);
     promise.then(data => console.log(data));     
   }
}

To get the value synchronously: Get the value of a Javascript Promise in a synchronous way