Setting values to variables within a component to enable universal access throughout the component in Angular 2

Question

Setting values to variables within a component to enable universal access throughout the component in Angular 2

In my Angular 2 project, I have a function that retrieves data from a database using an API. I've created a function that stores the data successfully in a variable named "ReqData", which is of type "any".

 this._visitService.getchartData().subscribe(data =>
{ 
  this.ReqData = data;
  console.log("ISubscribe", this.ReqData );
});
console.log("OSubscribe", this.ReqData );
this.ImpoData = this.getData(this.ReqData);

The issue I'm facing is that while the data can be accessed within the subscribe function, trying to access it outside of the subscribe results in getting undefined as output. Is there a way to also use the data outside of the subscribe function?

angular typescript components angular2-services angular2-directives

Answer 1

Answer №1

At this moment, this.ReqData can be accessed from anywhere in the component. However, it is important to ensure that you only call it after the code inside the subscribe function has executed. This happens when

this._visitService.getchartData()

retrieves the data, as the code inside subscribe runs asynchronously.

If you need to use the value immediately after retrieving it, make sure to do so within the subscribe block.

 this._visitService.getchartData().subscribe(data =>
{ this.ReqData = data
  console.log("ISubscribe", this.ReqData );
  this.ImpoData = this.getData( this.ReqData);

});
//Here this.ReqData is not defined

Edit: If you intend to utilize that value outside of the subscribe block, you can convert the observable to a promise and leverage the await/async pattern.

import 'rxjs/add/operator/toPromise';

//...
async yourMethod()
{
    try
    {
        this.ReqData = await this._visitService.getchartData().toPromise();
        //Here this.ReqData is accessible
        this.ImpoData = this.getData( this.ReqData);
    }
    catch(e)
    {
        //Handle your error here
    }


}

Answer 2

At this moment, this.ReqData can be accessed from anywhere in the component. However, it is important to ensure that you only call it after the code inside the subscribe function has executed. This happens when

this._visitService.getchartData()

retrieves the data, as the code inside subscribe runs asynchronously.

If you need to use the value immediately after retrieving it, make sure to do so within the subscribe block.

 this._visitService.getchartData().subscribe(data =>
{ this.ReqData = data
  console.log("ISubscribe", this.ReqData );
  this.ImpoData = this.getData( this.ReqData);

});
//Here this.ReqData is not defined

Edit: If you intend to utilize that value outside of the subscribe block, you can convert the observable to a promise and leverage the await/async pattern.

import 'rxjs/add/operator/toPromise';

//...
async yourMethod()
{
    try
    {
        this.ReqData = await this._visitService.getchartData().toPromise();
        //Here this.ReqData is accessible
        this.ImpoData = this.getData( this.ReqData);
    }
    catch(e)
    {
        //Handle your error here
    }


}

Setting values to variables within a component to enable universal access throughout the component in Angular 2

Answer №1

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