Having trouble retrieving the data returned from the service in an angular component

Question

Having trouble retrieving the data returned from the service in an angular component

Having trouble retrieving data from a service in an Angular component.

Here is the service code:

getData(fromDate: string, toDate: string): Observable<WfAverageTime[]>
  {
   const url ="http://testApi/getData"
   return this.http.get<someObject[]>(url);
 }

Now, let's take a look at the component code:

loadData(fromDate, toDate) {
  let resp = this.testService.getData(fromDate, toDate);
  resp.subscribe((reportData) => {
    this.DataSource.data = reportData as someObject[];
    this.data1 = reportData;
  })

data1 is a class-level variable. Despite being assigned a value, it cannot be accessed as this.data1 in other methods of the class.

angular typescript

Answer 1

Answer №1

To ensure the variable is used correctly within the subscribe function, it's important to include the logic where needed due to its asynchronous nature:

resp.pipe(
  tap((reportData ) => { '''Include your logic here''' })
).subscribe((reportData)=> {this.DataSource.data = reportData as someObject[];
    this.data1 = reportData;
    '''Include additional logic here'''
});

Another option is to pass the value to a child component where it will be resolved:

public reportData = this.testService.getData(fromDate, toDate);

Then in the HTML template:

<child-component [model]="reportData"></child-component>

You can utilize @Input set ... or ngOnChanges to handle any necessary logic.

Answer 2

To ensure the variable is used correctly within the subscribe function, it's important to include the logic where needed due to its asynchronous nature:

resp.pipe(
  tap((reportData ) => { '''Include your logic here''' })
).subscribe((reportData)=> {this.DataSource.data = reportData as someObject[];
    this.data1 = reportData;
    '''Include additional logic here'''
});

Another option is to pass the value to a child component where it will be resolved:

public reportData = this.testService.getData(fromDate, toDate);

Then in the HTML template:

<child-component [model]="reportData"></child-component>

You can utilize @Input set ... or ngOnChanges to handle any necessary logic.

Answer 3

Answer №2

In Angular, the get method of the HTTP client is designed to work asynchronously. This means that the code doesn't pause and wait for the data to be returned from the service call. Instead, it continues executing until the data is fetched successfully, at which point the logic inside the subscribe callback is triggered.

Consequently, even if data1 is a property of a class, it remains undefined until the service call is completed and the code reaches the subscribe callback.

To ensure proper access to these values, you must perform any operations requiring the data1 property within the subscribe callback function.

loadData(fromDate, toDate) { 
let httpResponse = this.testService.getData(fromDate, toDate);
httpResponse.subscribe((responseData) => {
this.DataSource.data = responseData as someObject[];
this.data1 = responseData; 
// At this stage, data1 contains the retrieved data
// Execute methods utilizing data1 here
})

Answer 4

In Angular, the get method of the HTTP client is designed to work asynchronously. This means that the code doesn't pause and wait for the data to be returned from the service call. Instead, it continues executing until the data is fetched successfully, at which point the logic inside the subscribe callback is triggered.

Consequently, even if data1 is a property of a class, it remains undefined until the service call is completed and the code reaches the subscribe callback.

To ensure proper access to these values, you must perform any operations requiring the data1 property within the subscribe callback function.

loadData(fromDate, toDate) { 
let httpResponse = this.testService.getData(fromDate, toDate);
httpResponse.subscribe((responseData) => {
this.DataSource.data = responseData as someObject[];
this.data1 = responseData; 
// At this stage, data1 contains the retrieved data
// Execute methods utilizing data1 here
})

Having trouble retrieving the data returned from the service in an angular component

Answer №1

Answer №2

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