Using HTTP POST to subscribe and implementing a try-catch block

Question

Using HTTP POST to subscribe and implementing a try-catch block

When using Angular2's http.post, I encountered an issue where the headers were not sent to the CORS server. To address this, I attempted to create a loop that would retry the request until it succeeds. However, this resulted in an endless loop. How can I resolve this?

 var headers = new Headers();
 headers.append('Content-Type', 'text/plain');

 this.again = true;
        while (this.again==true) {
           http.post('https://localhost:44300/account/getip', "", { headers: headers })
                .subscribe(
                (res2) => {
                    try {
                        this.ip = res2.json();
                        this.ipstr = this.ip.replace(/\./g, '-');
                        this.again = false;
                     }
                    catch (err) {
                        console.error(err);
                    }
                }
                );
        }

javascript http typescript angular

Answer 1

Answer №1

If you are looking to handle errors from a request, there are two approaches you can take:

Utilize the second callback of the subscribe method:

http.post('https://localhost:44300/account/getip', "", { headers: headers })
        .subscribe(
          (res2) => {
            (...)
          },
          (error) => {
            (...)
          }
        );
}

Alternatively, you can use the catch operator:

http.post('https://localhost:44300/account/getip', "", { headers: headers })
        .catch((error) => {
          (...)
        })
        .subscribe(
          (res2) => {
            (...)
          }
        );
}

For retrying requests, consider using the retry operator in conjunction with a timeout:

this.http.get('https://localhost:44300/account/getip',
          { search: params })
    .retryWhen(error => error.delay(500))
    .timeout(2000, return new Error('delay exceeded'))
    .map(res => res.json().postalCodes);

An example of using delay to introduce a time delay before making a new request is demonstrated...

You may also find this article on reactive programming and HTTP in Angular 2 interesting:

Answer 2

If you are looking to handle errors from a request, there are two approaches you can take:

Utilize the second callback of the subscribe method:

http.post('https://localhost:44300/account/getip', "", { headers: headers })
        .subscribe(
          (res2) => {
            (...)
          },
          (error) => {
            (...)
          }
        );
}

Alternatively, you can use the catch operator:

http.post('https://localhost:44300/account/getip', "", { headers: headers })
        .catch((error) => {
          (...)
        })
        .subscribe(
          (res2) => {
            (...)
          }
        );
}

For retrying requests, consider using the retry operator in conjunction with a timeout:

this.http.get('https://localhost:44300/account/getip',
          { search: params })
    .retryWhen(error => error.delay(500))
    .timeout(2000, return new Error('delay exceeded'))
    .map(res => res.json().postalCodes);

An example of using delay to introduce a time delay before making a new request is demonstrated...

You may also find this article on reactive programming and HTTP in Angular 2 interesting:

Answer 3

Answer №2

One way to handle network errors is by implementing the retry operator in your code:

http.post('https://example.com/api/getdata', "", { headers: customHeaders })
.retry(3)
.subscribe((response) => {
  this.data = response.json();
  this.formattedData = this.data.replace(/\./g, '-');
})

Answer 4

One way to handle network errors is by implementing the retry operator in your code:

http.post('https://example.com/api/getdata', "", { headers: customHeaders })
.retry(3)
.subscribe((response) => {
  this.data = response.json();
  this.formattedData = this.data.replace(/\./g, '-');
})

Using HTTP POST to subscribe and implementing a try-catch block

Answer №1

Answer №2

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