Strategies for Handling Errors within Observable Subscriptions in Angular

While working with code from themes written in the latest Angular versions and doing research online, I've noticed that many developers neglect error handling when it comes to subscription.

My question is: When is it necessary to handle errors in an Observable subscription?

Without error handling:


        this.myService.observable$.subscribe(
            (data) => {
                // do something with data
            }
        );
    

With error handling:


        this.myService.observable$.subscribe(
            (data) => {
                // do something with data
            },
            err => {
                // handle the error
            }
        );
    

I commonly see the first version being used, but...

Could neglecting error handling be a problem in a subscription?

Wouldn't this approach result in less robust, less testable code that is more likely to fail?

Answer №1

the importance of proper error handling click here for more

Let's explore the significance of error handling in Observables..

Illustrative Example:

this.service.send(this.shareData).subscribe(() => {

      // Ensuring successful data sharing

    }, (error) => {

      /* Handling errors such as Front End Errors and logging them in the backend DB to resolve and rectify */

      /* Below example checks if error type is not from API then logs it using the log service */

      if(error.type !== 'API') {
        this.logService.log({
          Level: 2,
          Message: 'Failed to setFromDB',
        });
      }
    });

Answer №2

It is important to handle errors effectively in order to provide users with feedback or revert to a default behavior.

For example, when attempting to connect to a REST service and encountering communication issues, notifying the user of connectivity problems or loading cached data may be necessary.

In another scenario, if the REST service returns an error, such as in the case of a booking app where a user tries to place an order for an out-of-stock item, displaying an error message informing the user that the item is no longer available is crucial.

Additionally, according to the Angular style guide:

The specifics of data management, including headers, HTTP methods, caching, error handling, and retry logic, should not concern components or other data consumers.

This underscores the importance of providing meaningful messages from your service.

Answer №3

Not directly related to your query, however, here is a solution for managing errors within the subscribe function in Angular version 16:

this.http.get(url).subscribe(
 {
   next: (data) => 
   {
     //perform a task
   },
   error: (error) =>
   {
     //deal with the error
   }
 }
);

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