从Angular 2中的Hal + JSON对象解析信息

Question

我有一个spring-data-rest存储库,它产生一个hal + json对象,我希望我的Angular 2前端能够接收和显示.

Hal + Json对象:

{
  "_embedded" : {
    "users" : [ {
      "name" : "Bob",
      "_links" : {
        "self" : {
          "href" : "http://localhost:4200/api/users/1"
        },
        "user" : {
          "href" : "http://localhost:4200/api/users/1"
        }
      }
    }, {
      "name" : "Joe",
      "_links" : {
        "self" : {
          "href" : "http://localhost:4200/api/users/2"
        },
        "user" : {
          "href" : "http://localhost:4200/api/users/2"
        }
      }
    } ]
  },
  "_links" : {
    "self" : {
      "href" : "http://localhost:4200/api/users"
    },
    "profile" : {
      "href" : "http://localhost:4200/api/profile/users"
    },
    "search" : {
      "href" : "http://localhost:4200/api/users/search"
    }
  },
  "page" : {
    "size" : 20,
    "totalElements" : 2,
    "totalPages" : 1,
    "number" : 0
  }
}

我有一个服务,对此api提出请求.

user.service.ts:

import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { User } from './user.model';
import { Observable } from 'rxjs';
import 'rxjs/add/operator/map'

@Injectable()
export class UserService {

  constructor(private http: Http) {
  }

  findAllUsers(): Observable<Array<User>> {
    return this.http.get('/api/users')
      .map((response: Response) => response.json())
      .map((data: Array<User>) => {
        return data;
      });
  }
}

然后我的users.component从服务中调用findAllUsers方法.

users.component.ts

import { Component, OnInit } from '@angular/core';
import { User } from './user.model';
import { UserService } from './user.service';

@Component({
  selector: 'app-users',
  providers: [UserService],
  templateUrl: './users.component.html',
  styleUrls: ['./users.component.css']
})
export class UsersComponent implements OnInit {
  users: User[];

  constructor(private userService: UserService) {
  }

  ngOnInit(): void {
   this.userService.findAllUsers().subscribe((data: Array<User>) => {
     this.users = data;
   });
  }

}

最后,users.component.html:

<h4>Users:</h4>

<div *ngFor="let user of users">
  {{user}}
</div>

在我看来,我得到一个错误说明:Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays.我不知道如何解决这个问题.

如果我data在服务中返回之前尝试使用调试器,那么我可以看到我的hal + json对象= data,我可以看到我想要的正确信息data._embedded_users.但是这不能映射到User [],因为_embedded它不是我的用户模型的属性.我是否需要先对Hal + Json对象做些什么？

Answer 1

我是否需要先对Hal + Json对象做些什么？

这不明显吗？只需提取服务中的数据即可

findAllUsers(): Observable<Array<User>> {
  return this.http.get('/api/users')
    .map((response: Response) => response.json())
    .map((data: any) => {
      return data._embedded.users as User[];
    });
}

你以前有过什么

.map((data: Array<User>) => {
  return data;
});

是不正确的,因为你假设传递给第二个的数据是map用户数组,而实际上它是整个HAL对象.将其更改为any允许您从中提取用户.