angular synchronous function call

Question

In the below code, the getElements function is not waiting for the getSChema() function to complete, it's running asynchronously, how do I make it synchronous function call, I want to wait until the getschema() function execution is completed

getSChema()
  {
    this.getPdiSchema(this.ApplicationsComponent.selectedApplication)
    .subscribe((res: any) => { 
      console.log("res:"+res);
     this.resdata=res;
            }
          );
  }

    getElements() {  
        let elements:any[]; 
          let complexType:any[];  
          let sequence:any[];  
          let elements1:any[]; 
          let elements2:any[]; 
          let complexType1:any[];  
          let sequence1:any[];   
          let elementsArray: PdiSchemaBase<any>[] = [];

    this.getSChema(); //wait until getSchema execution is complete

         elements =  this.resdata["xs:schema"]["xs:element"]
         complexType = elements[0]["xs:complexType"];
         sequence = complexType[0]["xs:sequence"];
         elements1 = sequence[0]["xs:element"];
         complexType1 = elements1[0]["xs:complexType"];
         sequence1 = complexType1[0]["xs:sequence"];
         this.pdiElements = sequence1[0]["xs:element"];  
         let i=1;
         for (let element of this.pdiElements)
         {
             console.log("printing elements:"+i)
           if(element["$"].type !== undefined)
           {
             console.log("element.type:"+element["$"].type)
               elementsArray.push(new TextboxElements({
               key: element["$"].name,
               label: element["$"].name,                       
               required: true,
               order: i
             }))
           }
            i=i + 1;
         }                  
      return elementsArray.sort((a, b) => a.order - b.order);
      }

If I add a Observable and subscribe to it, am not able to return the value from getElements

getElements()
{

      let elementsArray: PdiSchemaBase<any>[] = [];   
      console.log("calling get schema:");     
      console.log("this.selectedApplication:"+this.ApplicationsComponent.selectedApplication);   
      this.getPdiSchema(this.ApplicationsComponent.selectedApplication)
      .subscribe((res: any) => { 
       console.log("res:"+res);
       //code here....
        }
      );
         // this return doens't seems to work
         return elementsArray.sort((a, b) => a.order - b.order);
  }

tenderloin · Accepted Answer · 2018-03-27 13:02:08Z

1

It might be best to change getSChema() to return the observable.

getSChema() {
    return this.getPdiSchema(this.ApplicationsComponent.selectedApplication);
}

And then in getElements() you can subscribe to it

getElements() {
    ...
    this.getSChema().subscribe((res: any) => {
        // code to execute once it's completed
    })
}

Response to comment:

Remove getSChema() from getElements() and instead where you call getElements() use something along the lines of:

this.getSChema().subscribe((res: any) => {
    this.resdata = res;
    this.elements = this.getElements();
});

edited Mar 27, 2018 at 13:02

answered Mar 27, 2018 at 12:11

tenderloin

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2 Comments

Divya Neelaiah Over a year ago

if I add a Subscribe in getElements how do i return the value "return elementsArray.sort((a, b) => a.order - b.order);"

tenderloin Over a year ago

How are you calling getElements()? Are you doing something like this.elements = this.getElements()? Assuming something along the lines of this I'll update the answer

AVJT82 · Accepted Answer · 2018-03-30 15:30:57Z

0

If you want to return return elementsArray.sort((a, b) => a.order - b.order); you can use map instead of subscribe, i.e return an observable and the method that expects that result can subscribe, so something in the line of....

getElements() {
  return this.getSchema()
    .map(res => {
      // do your stuff here, then....
      return elementsArray.sort((a, b) => a.order - b.order);
    });
}

And the function that is calling getElements...

myFunction() {
  this.getElements()
    .subscribe(data => console.log(data));
}

or you could maybe rather just call getSchema() directly, that I would do :)

answered Mar 30, 2018 at 15:30

AVJT82

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