Angular Material + GAPI:table 显示行,但单元格为空

Angular Material + GAPI: table shows rows, but with empty cells

我正在整合 angular material 和 Google api。我想在 table 中显示 api 的响应。问题是 mat-table 行的 mat-cell 未填充,但显示了该行。这是我的 table:

    <mat-table [dataSource]="dataSource">

    <ng-container matColumnDef="name">
      <mat-header-cell *matHeaderCellDef> Name </mat-header-cell>
      <mat-cell *matCellDef="let user"> {{user.name}} </mat-cell>
    </ng-container>
    <ng-container matColumnDef="age">
      <mat-header-cell *matHeaderCellDef> Age </mat-header-cell>
      <mat-cell *matCellDef="let user"> {{user.age}} </mat-cell>
    </ng-container>
    <ng-container matColumnDef="city">
      <mat-header-cell *matHeaderCellDef> City </mat-header-cell>
      <mat-cell *matCellDef="let user"> {{user.city}} </mat-cell>
    </ng-container>
    <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
    <mat-row *matRowDef="let row; columns: displayedColumns;"></mat-row>
  </mat-table>

这是我创建的界面:

    export interface User { name: string; age: number; city: string; }

这是与 table 关联的组件:

    export class UsertableComponent implements OnInit, OnChanges {
  @Input() apiReady: boolean;

  dataSource: UserDataSource;
  displayedColumns = ['name', 'age', 'city'];

  constructor(private userService: UserService) {

  }

  ngOnInit() {

  }

  ngOnChanges(changes: SimpleChanges) {
    if (this.apiReady) {
      this.dataSource = new UserDataSource(this.userService);
    }
  }
}

export class UserDataSource extends DataSource<any> {
  constructor(private userService: UserService) {
    super();
  }

  connect(): Observable<User[]> {
    return this.userService.getUsers();
  }

  disconnect() {

  }
}

这里,终于是噩梦了。调用 gapi 和 return 数据的服务。我可以确保 api 响应,特别是这行代码 response.result.users[0].name.fullName 对应于具有值的字符串对象.

export class UserService {
  private serviceUrl = environment.apiUrl + '/getcust/';
  private apiLoaded = false;
  constructor(private http: HttpClient) { }

  getUsers(): Observable<User[]> {
    /* // THIS WORKS!!!
        const u: User = {
          'name': 'ss',
          'city': 'città',
          'age': 3
        };
        return Observable.create(observable => {
          observable.next([u]);
          observable.complete();
        });
     */

    return Observable.create(observable => { // THIS DOESN'T WORK
      return gapi.client.directory.users.list({
        'customer': 'my_customer',
        'maxResults': 1,
        'orderBy': 'email'
      }).then(response => {

        const u: User = {
          'name': response.result.users[0].name.fullName,
          'city': 'citta',
          'age': 3
        };

        observable.next([u]);
        observable.complete();
      });
    });
  }
}

如您在评论中所见,注释行有效,其他行无效。

Result with empty cells

Result with populated cells, without calling GAPI

解决方法是:

导入这个:

import {ChangeDetectorRef} from '@angular/core';

组件的构造函数:

constructor(private cd: ChangeDetectorRef) {
  }

在ngInit中初始化数据源:

    ngOnInit() {
    this.dataSource = new UserDataSource();
}

使用BehaviorSubject(以及方法asObservable)可以随时改变数据源的内容,但是当数据改变的时候table别忘了打电话:

this.cd.detectChanges();

更新单元格内容