ngFor生产空内容-角7常春藤

Question

我在玩角7和常春藤，我不能得到一个for循环来吐出任何值。

我的代码：

@Component({
  selector: 'app-asset-list',
  templateUrl: './asset-list.component.html',
  styleUrls: ['./asset-list.component.scss']
})
export class AssetListComponent implements OnInit {

  asset = {name: 'test'};
  assets: Asset[] = [this.asset];
  cols: any[] = [];


  colors: any[] = ['red', 'blue', 'yellow']; // EDIT: added this for debug

  constructor(private assetService: AssetService) {

  }

  ngOnInit() {
    // this.assetService.getAssets().subscribe((value => this.assets = value));
    this.cols = [
      {field: 'name', header: 'Name'}
    ];
  }

}

我的html：

<h3>Asset List</h3>

<!--DEBUG-->
{{ assets | json }}
{{ cols |json}}

<!--Does not show-->
<div *ngIf="assets.length > 0">
  Oh, its greater than 0.
</div>

<!--also does not show-->
<ul>
  <li *ngFor="let a of assets">
    {{a}}
  </li>
</ul>

<!--also does not show-->
<ul>
  <li *ngFor="let c of cols">
    {{c}}
  </li>
</ul>

<!--EDIT: added for debug... also does not show?-->
<ul>
  <li *ngFor="let c of colors">
    {{c}}
  </li>
</ul>

<!--ultimately, this is what I wanted, but the above don't even work-->
<p-table [value]="assets">
  <ng-template pTemplate="header">
    <tr>
      <th *ngFor="let col of cols">
        {{col.header}}
      </th>
    </tr>
  </ng-template>
  <ng-template pTemplate="body" let-asset>
    <tr>
      <td *ngFor="let col of cols">
        {{asset[col.field]}}
      </td>
    </tr>
  </ng-template>
</p-table>

以及产出：

​

​

正如您所看到的，我从服务中取出了返回的Observable，但它仍然无法工作。我希望在屏幕上看到一些东西，因为调试行显示了一些内容。我遗漏了什么？

我添加了一个字符串的数组colors只是为了更多的理智检查..。仍然没有显示。控制台中没有错误。

我的package.json依赖关系：

"dependencies": {
    "@angular/animations": "7.2.4",
    "@angular/common": "7.2.4",
    "@angular/compiler": "~7.2.4",
    "@angular/core": "7.2.4",
    "@angular/forms": "7.2.4",
    "@angular/platform-browser": "~7.2.0",
    "@angular/platform-browser-dynamic": "~7.2.0",
    "@angular/router": "~7.2.0",
    "core-js": "^2.5.4",
    "primeicons": "^1.0.0",
    "primeng": "^7.0.5",
    "rxjs": "~6.3.3",
    "tslib": "^1.9.0",
    "zone.js": "~0.8.26"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.13.0",
    "@angular/cli": "~7.3.1",
    "@angular/compiler-cli": "7.2.4",
    "@angular/language-service": "7.2.4",
    "@types/node": "~8.9.4",
    "@types/jasmine": "~2.8.8",
    "@types/jasminewd2": "~2.0.3",
    "codelyzer": "~4.5.0",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~3.1.1",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~2.0.1",
    "karma-jasmine": "~1.1.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.4.0",
    "ts-node": "~7.0.0",
    "tslint": "~5.11.0",
    "typescript": "~3.2.2"
  }

我不能在一堆闪电战中复制..。我想问题与常春藤有关。话虽如此，这里是一个堆栈闪电战。

Answer 1

在一个新的CLI项目中运行--experimentalIvy标志时，我遇到了同样的问题。

我还创建了一个问题：https://github.com/angular/angular/issues/30081

尽管如此，我尝试使用以下方法将core和cli更新到下一个版本：

ng update @angular/core@next @angular/cli@next

它适用于V8.0.0-beta.14，所以.我不确定有人会在版本7中修复它，而8即将发布。

还创建了一个带有分离分支的Github回购程序，以便于复制，您可以在这里查看它：https://github.com/eliraneliassy/ivy-ngfor-bug

Answer 2

为了查看输出，您可能需要使用点运算符访问一个属性，否则它将仅仅是[Object Object]。

<ul>
  <li *ngFor="let a of assets">
    {{a.name}}
  </li>
</ul>

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