Exploring the new possibilities of Angular 5: Enhanced REST API service with paginated data and object mapping capabilities

After implementing pagination in my REST API backend, I now need to update my Angular services to accommodate the changes.

Instead of simply returning an array of objects, the API will now return JSON responses structured like this:

{
    "count": 0,
    "next": null or url,
    "previous": null or url,
    "results": [..]
}

Here is my current service which needs modification due to these updates:

list(): Observable<StudentCourse[]> {
  let url = `${this.url}/student_courses/`;
  return this.httpClient.get<StudentCourse[]>(url, { headers: this.headers })
    .pipe(
      catchError(this.handleError('GET student-course', []))
    );
}

I am looking for advice on how to map the results to the array of objects (StudentCourse[]) in a simple way. Additionally, I would like to save the URLs of next and previous directly in the service for future use. Any suggestions?

Answer №1

To streamline the JSON response page layout, you can define a wrapper interface:

interface IPageResponse<T> {
    count: number,
    next: string | null,
    previous: string | null,
    results: T[]
}

You can then integrate this interface into your code to replace raw arrays:

fetchData(): Observable<IPageResponse<UserDetails>> {
  let endpoint = `${this.apiUrl}/users/`;
  return this.http.get<IPageResponse<UserDetails>>(endpoint, { headers: this.headers })
    .pipe(
      catchError(this.handleErrors('GET user data', []))
    );
}

For accessing values like previous and next, you have the flexibility to do so within the service or the consumer side.

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