Primeng数据表无法绑定数据

Question

用户-list.page.html

<p-dataTable [value]="userser" [rows]="10" scrollable="true" scrollHeight="200px">
<p-column field="USER_NAME" header="USER ID"></p-column>
<p-column field="USER_ID" header="USER NAME" [sortable]="true"></p-column>
<p-column field="DEPT_NAME" header="DEPARTMENT" [sortable]="true"></p-column>
<p-column field="ACTIVE" header="ACTIVE" [sortable]="true"></p-column></p-dataTable>

用户-list.page.ts

import User from './services/user';
import {UserService} from './services/user.service';
export class Userdetails {
    userser: User[];
    constructor(private userservice: UserService) {}
    ngOnInit() {
        this.userservice.getUsers().subscribe((userser: any) => this.userser = userser);
    }
}

用户-list.json

{"userdata":
    {"userlist":[
        {"USER_ID":"SS","USER_NAME":"KUMAR"},
        {"USER_ID":"SUDHEER","USER_NAME":"SS"},
        {"USER_ID":"BHARGAV","USER_NAME":"TEJ"}
    ]}
},

user-service.ts （用于绑定JSON文件中的值的HTTP服务）

@Injectable()
export class UserService {
    constructor(private http: Http) {
    }

    getUsers(): Observable<User[]> {
        return this.http.get('app/assets/user-list.json')
            .map(response => response.json().data as User[]);
    }
}