What is the best way to detect errors in Angular 2?

Question

What is the best way to detect errors in Angular 2?

I am making a server call as shown below:

In the case of success,

STATUS---200

{error_code: 0, status: "success", results: [,…], message: "Album successfully found."}

If there is a failure, STATUS---401

 Login credentials are incorrect.

To handle this, I have implemented the following code:

 Upon sending a POST request to this.serverUrl+'login' with loginForm.value and headers,
        .subscribe(response => {
            if (response.json().error_code === 0) {
               console.log('success'); 
            } else {
               console.log('fail'); 
            }
        }) 
  }

However, in the current scenario, an error (401-status) occurs. This prevents the execution from going into the else statement. Can someone provide assistance on how to properly handle or catch this error? Thank you.

angular typescript angular2-routing angular-http

Answer 1

Answer №1

The subscription includes an error handling function:

 this.http.post(this.serverUrl+'login', loginForm.value, {headers: headers})
        .subscribe(
        (response) => {
            if (response.json().error_code === 0) {
               console.log('Request successful'); 
            } else {
               console.log('Request failed'); 
            }
        },
        (error)=>{
            console.log(error);
        }
     ) 
  }

See documentation example here: https://angular.io/docs/ts/latest/guide/server-communication.html#!#the-herolistcomponent-class

Answer 2

The subscription includes an error handling function:

 this.http.post(this.serverUrl+'login', loginForm.value, {headers: headers})
        .subscribe(
        (response) => {
            if (response.json().error_code === 0) {
               console.log('Request successful'); 
            } else {
               console.log('Request failed'); 
            }
        },
        (error)=>{
            console.log(error);
        }
     ) 
  }

See documentation example here: https://angular.io/docs/ts/latest/guide/server-communication.html#!#the-herolistcomponent-class

Answer 3

Answer №2

Using the method entails providing 3 specific parameters: the first one is executed upon receiving a successful response, the second is triggered in case of an error response, and the third is activated once the process is completed. Give this a try:

this.fetchData(params).using(response => {
     console.log('Success');
}, error => {
     console.log('Error')
});

I highly suggest checking out the angular tutorial as well as the Rxjs Subscribe documentation.

Answer 4

Using the method entails providing 3 specific parameters: the first one is executed upon receiving a successful response, the second is triggered in case of an error response, and the third is activated once the process is completed. Give this a try:

this.fetchData(params).using(response => {
     console.log('Success');
}, error => {
     console.log('Error')
});

I highly suggest checking out the angular tutorial as well as the Rxjs Subscribe documentation.

Answer 5

Answer №3

Another option is to utilize the .catch method:

this.http.post(this.serverUrl+'login', loginForm.value, {headers: headers})
        .subscribe(response => {
            if (response.json().error_code === 0) {
               console.log('success'); 
            } else {
               console.log('fail'); 
            }
        }).catch((err)=>{console.log(err)});

Answer 6

Another option is to utilize the .catch method:

this.http.post(this.serverUrl+'login', loginForm.value, {headers: headers})
        .subscribe(response => {
            if (response.json().error_code === 0) {
               console.log('success'); 
            } else {
               console.log('fail'); 
            }
        }).catch((err)=>{console.log(err)});

What is the best way to detect errors in Angular 2?

Answer №1

Answer №2

Answer №3

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