Tips for obtaining response headers

Question

Tips for obtaining response headers

Currently, I am utilizing Angular version 15.0 and retrieving a list of items from the backend (ASP.NET Core 5) with an additional item attached to the header. The GET method in the client-side service is as follows:

/** GET Paged commodities from the server ===============================*/
  getPagedCommodities(pageSize: number, pageNumber: number): Observable<CommodityForList[]> {
    let params: HttpParams = new HttpParams();
    params = params.append('pageSize', pageSize);
    params = params.append('pageNumber', pageNumber);

    const headers = new HttpHeaders({
      observe: 'response'
    });

    return this.http.get<CommodityForList[]>(this.baseUrl + '/getPagedCommodities/', { headers, params });

  }

This function sends two parameters to the server, retrieves a commodities list along with totalCount to facilitate paging, and sets the length property of mat-paginator. Additionally, the commodities list is set as an observable to enable dynamic search functionality for users. In the commoditiesList component, the code snippet for achieving this purpose is shown below:

 commoditiesForList$!: Observable<CommodityForList[]>;
 
this.commoditiesForList$ = this.commoditiesService.getPagedCommodities(this.pageSize, this.pageIndex+1);
 
this.commoditiesForList$.subscribe( res => {
      const totalCount = res.headers.get('X-Pagination');
    })

However, an error occurs stating:

Property 'headers' does not exist on type 'CommodityForList[]'.

Changing the type of commoditiesForList$ to

HttpResponse<CommodityForList[]>

may resolve the error, but it introduces a problem with receiving the commodities list as an observable. Is there a viable solution to obtain the commodities list as an observable while extracting the totalCount separately from the header? Your input is greatly appreciated.

javascript angular typescript

Answer 1

Answer №1

For more details, visit https://angular.io/guide/http#reading-the-full-response

There may be additional information about the transaction that is not included in the response body. Servers sometimes send specific headers or status codes to signify certain conditions that are crucial to the application's workflow.

  getPagedCommodities(pageSize: number, pageNumber: number): Observable<HttpResponse<CommodityForList[]>> {
    // ...
    return this.http.get<CommodityForList[]>(this.baseUrl + '/getPagedCommodities/', { headers, params });
  }

You can access the content in the body attribute.

Also check out Angular: HttpClient read full response with Observable Array.

Answer 2

For more details, visit https://angular.io/guide/http#reading-the-full-response

There may be additional information about the transaction that is not included in the response body. Servers sometimes send specific headers or status codes to signify certain conditions that are crucial to the application's workflow.

  getPagedCommodities(pageSize: number, pageNumber: number): Observable<HttpResponse<CommodityForList[]>> {
    // ...
    return this.http.get<CommodityForList[]>(this.baseUrl + '/getPagedCommodities/', { headers, params });
  }

You can access the content in the body attribute.

Also check out Angular: HttpClient read full response with Observable Array.

Answer 3

Answer №2

After reviewing your example, it is recommended to utilize the following configuration in your HTTP request:

{responseType: 'json', observe: 'events' }

. You can view a functional demonstration on stackblitz - one request

commoditiesForList$!: BehaviourSubject<CommodityForList[]>;
totalCount$!: BehaviourSubject<any>;

constructor(commoditiesService: CommoditiesService) {
this.commoditiesService.getPagedCommodities(this.pageSize, this.pageIndex+1).subscribe(res => {
  this.commoditiesForList$.next(res.body)
  this.totalCount$.next(headers.get('X-Pagination'))
})
}

Revised Answer

In your specific case, it is suggested to configure your HTTP request with these settings:

{responseType: 'json', observe: 'events' }

. An illustration of this setup can be found on stackblitz - two requests - shared pipe

Edit: To prevent dual requests, note that the GET request utilizes the share operator from rxjs. Special thanks to Arber for pointing this out.

getPagedCommodities(pageSize: number, pageNumber: number): Observable<CommodityForList[]> {
    let params: HttpParams = new HttpParams();
    params = params.append('pageSize', pageSize);
    params = params.append('pageNumber', pageNumber);

    const headers = new HttpHeaders({
      observe: 'response'
    });

    return this.http.get<CommodityForList[]>(this.baseUrl + '/getPagedCommodities/',
    { headers, params, responseType: 'json',observe: 'events'}).pipe(share());

  }

Upon implementation, data and headers can be accessed as displayed

 commoditiesForList$!: Observable<CommodityForList[]>;
 
this.commoditiesForList$ = this.commoditiesService.getPagedCommodities(this.pageSize, this.pageIndex+1).pipe(
    map((res) => (res as any).body));

this.totalCount$ =  this.commoditiesService.getPagedCommodities(this.pageSize, this.pageIndex+1).pipe(
    map((res) => (res as any).headers)), map(headers => headers.get('X-Pagination')));

Additional Resources: https://angular.io/guide/http#requesting-data-from-a-server

Answer 4

After reviewing your example, it is recommended to utilize the following configuration in your HTTP request:

{responseType: 'json', observe: 'events' }

. You can view a functional demonstration on stackblitz - one request

commoditiesForList$!: BehaviourSubject<CommodityForList[]>;
totalCount$!: BehaviourSubject<any>;

constructor(commoditiesService: CommoditiesService) {
this.commoditiesService.getPagedCommodities(this.pageSize, this.pageIndex+1).subscribe(res => {
  this.commoditiesForList$.next(res.body)
  this.totalCount$.next(headers.get('X-Pagination'))
})
}

Revised Answer

In your specific case, it is suggested to configure your HTTP request with these settings:

{responseType: 'json', observe: 'events' }

. An illustration of this setup can be found on stackblitz - two requests - shared pipe

Edit: To prevent dual requests, note that the GET request utilizes the share operator from rxjs. Special thanks to Arber for pointing this out.

getPagedCommodities(pageSize: number, pageNumber: number): Observable<CommodityForList[]> {
    let params: HttpParams = new HttpParams();
    params = params.append('pageSize', pageSize);
    params = params.append('pageNumber', pageNumber);

    const headers = new HttpHeaders({
      observe: 'response'
    });

    return this.http.get<CommodityForList[]>(this.baseUrl + '/getPagedCommodities/',
    { headers, params, responseType: 'json',observe: 'events'}).pipe(share());

  }

Upon implementation, data and headers can be accessed as displayed

 commoditiesForList$!: Observable<CommodityForList[]>;
 
this.commoditiesForList$ = this.commoditiesService.getPagedCommodities(this.pageSize, this.pageIndex+1).pipe(
    map((res) => (res as any).body));

this.totalCount$ =  this.commoditiesService.getPagedCommodities(this.pageSize, this.pageIndex+1).pipe(
    map((res) => (res as any).headers)), map(headers => headers.get('X-Pagination')));

Additional Resources: https://angular.io/guide/http#requesting-data-from-a-server

Tips for obtaining response headers

Answer №1

Answer №2

Revised Answer

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