What is the best practice for subscribe method in angular?

Question

I'm am just wondering which one is the best practice for angular.

Here is an observable method.

downloadRequest(ids: number[], url: string, inputName: string): Observable<void> {
 const formData = new FormData();
 formData.append(inputName, ids.join(','));
 return this.http.post<void>(url, formData)                                                    
}

This is the subscribe method that I use.

this.downloadService.downloadRequest(data.blabla, url, 'blabla').subscribe(res => {
 alert('HEY');
 }, err => {
  console.log(err);
 });

In this case, this alert is going to work only if the response status equals 200. Is it right? The observable method returns void. So, I can not get a response status for sure.

Instead, should I use the below case? The observable method returns any. I can get a response status.

downloadRequest(ids: number[], url: string, inputName: string): Observable<any> {
 const formData = new FormData();
 formData.append(inputName, ids.join(','));
 return this.http.post<any>(url, formData, {observe: 'response'})                                                    
}

this.downloadService.downloadRequest(data.blabla, url, 'blabla').subscribe(res => {                  
 if (res.status === 200) {                                                                    
   alert('HEY');
 }
 }, err => {
  console.log(err);
 });

Answer 1

With normal case of http.post method. It only return the content of body or exception.

However, you can customize the data return HttpResponse.

From document:

https://angular.io/guide/http#reading-the-full-response

https://angular.io/api/common/http/HttpResponse

getConfigResponse(): Observable<HttpResponse<Config>> {
  return this.http.get<Config>(
    this.configUrl, { observe: 'response' });
}

then you can capture status, headers...

.subscribe(resp => {
   console.log(resp.status);
   console.log(resp.statusText);
    });

Answer 2

When you subscribe to an Observable returned by HttpClient , you can specify up to 3 callbacks, in order:

• next , which receives the body of the successful response (or null if the successful response had no body)
• error , which receives the error the prevented this request from succeeding
• complete , which is invoked after next if the request was successful

As you can see, next is invoked for every successful request, even if the response has no body.

So, I can not get a response status for sure.

That is a misunderstanding. Every HTTP response contains a response code. It may or may not contain a body, but it will always contain a response code, and that indicates whether the request was successful, and determines whether HttpClient will invoke next or error .

As an aside, all response codes of the form 2xx indicate success , not just 200. Receiving a 201 Created or a 204 No Content is no cause for alarm.