Passing data from Parent to Child via template

问题

I have a template user like following:

<div class="jumbotron">
  <div class="container">
    <h2><i class="fa fa-user"></i> {{username}}</h2>
    <p><i class="fa fa-star"></i> {{reputation}}</p>
  </div>
</div>
<app-list user={{username}}"></app-list>

My component for app-list looks like:

export class ListComponent implements OnInit {
  @Input() user: string;

  constructor() { }

  ngOnInit() {   
    console.log(this.user);
  }  

}

The username and reputation is correctly shown on the page. However the username value is not passed correctly to the sub component app-list as it only print out an empty string.

How can I pass the username to the app-list component?

Edit

The user component looks like:

export class UserComponent implements OnInit {

  private username: string;
  private reputation: number;

  constructor(private route: ActivatedRoute, private apiService: ApiService) {
  }

  ngOnInit() {
    this.route.params.subscribe((params: Params) => (
      this.apiService.getUser(params['username']).subscribe((response: Response) => {
          console.log(response.json());
          this.username = response.json().username;
          this.reputation = response.json().reputation;
        }, (error) => {
          if (error.status === 404) {
            // Todo: redirect to 404 page
          }
        }
      )
    ));
  }

}

回答1:

It should be,

<app-list [user]="username"></app-list>

回答2:

Alternatively you can use @ViewChild() decorator to achieve the below

export class UserComponent implements OnInit {
 @ViewChild(AppListCopmonent) appList: AppListComponent;

  ngOnInit() {   
      this.appList.user = this.username
 }  
}

Update based on chat : Before assigning the value check if the data is there as

this.apiService.getUser(params['username']).subscribe((response: Response) => {      
  if(response){
      console.log(response.json());
      this.username = response.json().username;
      this.reputation = response.json().reputation;
    });

来源：https://stackoverflow.com/questions/44869853/passing-data-from-parent-to-child-via-template

标签

angular

angular2-template