How to get my resource data from a HAL response?

Question

I'm building an API using Spring Boot 2 and the Angular 6 client has to deal with responses such as this one for example :

{
  "_embedded" : {
    "userResourceList" : [ {
      "firstname" : "Stephane",
      "lastname" : "Toto",
      "email" : "toto@yahoo.se",
      "confirmedEmail" : false,
      "password" : "bWl0dGlwcm92ZW5jZUB5YWhvby5zZTptaWduZXRjNWRlMDJkZS1iMzIwLTQ4Y2YtOGYyMS0wMmFkZTQ=",
      "userRoles" : [ {
        "role" : "ROLE_ADMIN",
        "id" : 1
      } ],
      "_links" : {
        "self" : {
          "href" : "http://localhost:8080/api/users/1"
        },
        "roles" : {
          "href" : "http://localhost:8080/api/users/1/roles"
        }
      },
      "id" : 1
    } ]
  },
  "_links" : {
    "self" : {
      "href" : "http://localhost:8080/api/users"
    }
  },
  "page" : {
    "size" : 20,
    "totalElements" : 1,
    "totalPages" : 1,
    "number" : 0
  }
}

All REST resources endpoints would retrun such HALified responses.

I wonder how to deal with these. If there is such library that eases the parsing and extraction of the actual payload.

I heard of the RestAngular library but I'm not so sure it's what I want.

Maybe something less invasive only assisting in the parsing like :

const user: User = hal2Json.parse(response);

UPDATE: I didn't find any such library and so I resorted to this implementation:

public getSome(searchTerm: string, sortFieldName: string, sortDirection: string, currentPage: number, limit: number): Observable {
  let httpParams = new HttpParams()
  .set('page', currentPage.toString())
  .set('size', limit.toString());
  if (searchTerm) {
    httpParams = httpParams.append('searchTerm', searchTerm);
  }
  if (sortFieldName && sortDirection) {
    httpParams = httpParams.append('sort', sortFieldName + ',' + sortDirection);
  }
  return this.httpService.get(this.usersUrl, httpParams);
}

export class UsersApi extends PaginationApi {

  constructor(users: User[], currentPageNumber: number, elementsPerPage: number, totalElements: number, totalPages: number) {
      super(currentPageNumber, elementsPerPage, totalElements, totalPages);
      this.users = users;
  }

  users: User[];

}

getUsers(searchTerm: string, sortFieldName: string, sortDirection: string, currentPageNumber: number): Observable {
  return this.userService.getSome(searchTerm, sortFieldName, sortDirection, currentPageNumber, this.elementsPerPage)
    .pipe(
      map(response => {
        return new UsersApi(
          response._embedded.userResourceList as User[],
          this.paginationService.correctPageNumberMispatch(response.page.number),
          response.page.size,
          response.page.totalElements,
          response.page.totalPages
        );
      })
    );
}

user_8390382 · Answer

Define an interface to wrap the HAL response. This is how I did it for my book service:

// book.service.ts
import { Injectable } from '@angular/core';
import { Book } from '../book';
import { Observable, map } from 'rxjs';
import { HttpClient } from '@angular/common/http';

@Injectable({
    providedIn: 'root'
})
export class BookService {

    private booksUrl = 'http://localhost:8080/books';

    constructor(private http: HttpClient) { }

    getBooks(): Observable {
        return this.http.get(this.booksUrl).pipe(
            map(response => response._embedded.bookList)
        );
    }
}

interface GetBooksResponse {
    _embedded: {
        bookList: Book[];
        _links: {self: {href: string}};
    };
}

The HAL response:

Credit goes to this post: https://medium.com/@tbrouwer/spring-boot-backend-for-angular-tour-of-heroes-106dc33a739b

user_1205871 · Answer

You could try the halfred npm module. Seems to do what you want:

https://www.npmjs.com/package/halfred

npm install halfred --save

then import it:

import * as 'halfred' from 'halfred' // something like this should work

then use it:

const resource = halfred.parse(object)

How to get my resource data from a HAL response?

2 Answers