ngIf在ng容器在垫子桌里面

时间:2018-11-07 14:56:57

标签: angular angular5

我是Angular的新手。 我有以下问题:我只需要在表上显示状态==“完成”的行。我了解为什么我的代码无法按我想要的方式工作,但无法为我找到合适的解决方案。

这是.ts文件:

import { Component, OnInit } from '@angular/core';

 import { TestCase } from '../test-cases/models/test-case.model';
 import { TestCaseService } from '../test-case.service';

@Component({
  selector: 'app-test-cases-view',
  templateUrl: './test-cases-view.component.html',
  styleUrls: ['./test-cases-view.component.css']
})
export class TestCasesViewComponent implements OnInit {
  testCases: TestCase[];
  displayedColumns: string[] = ['testCaseName', 'testCaseDescription','id','created','status', 'xls'];
  constructor(private testCaseService: TestCaseService) { }

  ngOnInit() {
    this.getTestCases();
  }

  postRequest(testCaseId: string):void {
    this.testCaseService.postTestResult(testCaseId);
  }

  getTestCases(): void {
    this.testCaseService.getTestCases()
      .subscribe(testCases => this.testCases = testCases);
  }

}

test-case.model.ts文件:

import { TestCaseParams } from './test-case-params.model';

export class TestCase {
  public testCaseName:string;
  public testCaseDescription:string;
  public parameters:TestCaseParams;
  public id:string;

  constructor () {
    this.parameters= new TestCaseParams();
  }
}

test-case-params.model.ts

import { EditedVar } from './replacement.model';
import { FilterVar } from './filter.model';
import { OutputVar } from './output.model';

export class TestCaseParams {
  public appsCount: number;
  public algId: number;
  public product: string;
  public invokeConsolidation: boolean;
  public invokeProdStrategy: boolean;
  public filterVars: FilterVar[];
  public editedVars: EditedVar[];
  public outputVars: OutputVar[];
  public fromDate: Date;
  public toDate:Date;
}

replacement.model.ts:

export class EditedVar {
  public path:string;
  public value:string;
}

filter.model.ts:

export class FilterVar{
  public filter:string;
  public filterType:string;
  public filterValue:string;
  public varch:boolean;
}

output.model.ts:

export class OutputVar {
  public path:string;
  public alias:string;
  public type:string;
}

这是有效的html文件:

<div id="view-component">
  <h2>Test Cases</h2>

  *some code just don't fit in the question*

    <ng-container matColumnDef="xls">
      <th mat-header-cell *matHeaderCellDef> Xls report </th>
      <td mat-cell *matCellDef="let testCase">
        <button *ngIf = "testCase.status == 'FINISHED'" (click)="postRequest(testCase.id)">Make Excel report</button>
      </td>
    </ng-container>

    <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
    <tr mat-row *matRowDef="let row; columns: displayedColumns;"></tr>
  </table>
</div>

这是我尝试做的事情:

<table mat-table [dataSource]="testCases" class="mat-elevation-z8">

    <ng-container *ngIf = "testCase.status == 'FINISHED'" matColumnDef="testCaseName">
      <th mat-header-cell *matHeaderCellDef> testCaseName </th>
      <td mat-cell *matCellDef="let testCase"> {{testCase.testCaseName}} </td>
    </ng-container>

    <ng-container *ngIf = "testCase.status == 'FINISHED'" matColumnDef="testCaseDescription">
      <th mat-header-cell *matHeaderCellDef> testCaseDescription </th>
      <td mat-cell *matCellDef="let testCase"> {{testCase.testCaseDescription}} </td>
    </ng-container>

    <ng-container *ngIf = "testCase.status == 'FINISHED'" matColumnDef="id">
      <th mat-header-cell *matHeaderCellDef> Report Id </th>
      <td mat-cell *matCellDef="let testCase"> {{testCase.id}} </td>
    </ng-container>

    <ng-container *ngIf = "testCase.status == 'FINISHED'" matColumnDef="created">
      <th mat-header-cell *matHeaderCellDef> Created </th>
      <td mat-cell *matCellDef="let testCase"> {{testCase.created | date: 'dd/MM/yyyy hh:mm:ss'}} </td>
    </ng-container>

    <ng-container *ngIf = "testCase.status == 'FINISHED'" matColumnDef="status">
      <th mat-header-cell *matHeaderCellDef> Status </th>
      <td mat-cell *matCellDef="let testCase"> {{testCase.status}} </td>
    </ng-container>

    <ng-container *ngIf = "testCase.status == 'FINISHED'" matColumnDef="xls">
      <th mat-header-cell *matHeaderCellDef> Xls report </th>
      <td mat-cell *matCellDef="let testCase">
        <button (click)="postRequest(testCase.id)">Make Excel report</button>
      </td>
    </ng-container>

    <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
    <tr mat-row *matRowDef="let row; columns: displayedColumns;"></tr>
  </table>

如您所见,我不想以任何状态显示不等于“完成”的行。对于此代码,我收到以下错误:

  

错误TypeError:无法读取未定义的属性“状态”       在Object.eval [作为updateDirectives](TestCasesViewComponent.html:6)

我知道我需要将let testCase放置在其他位置,因此它将在ng容器级别上定义,但是我不知道在哪里。

2 个答案:

答案 0 :(得分:1)

该错误是因为 testCase 未定义,并且在javascript中访问属性(例如 testCase.status )中一个未定义的对象将始终抛出该错误。

但是首先没有定义testCase的原因是因为*ngIf将在方法getTestCases()之前运行

您有两种可能的解决方案:

  1. 实例化对象;

  2. 使用另一个* ngIf检查testCase是否未定义。

例如:

    <div *ngIf="testCase">
       <div *ngIf="testCase.status == 'FINISHED'">

       </div>
    </div>

换句话说,当您访问testCase中的属性时,只需确保*ngIf处于未定义状态即可。

答案 1 :(得分:1)

您可以过滤从Observable获得的数组,而不是在mat-table级别进行过滤,而是将过滤后的数组分配为数据:

getTestCases(): void {
  this.testCaseService.getTestCases()
    .subscribe(testCases => this.testCases = testCases.filter(({ status }) =>
      status === 'FINISHED',
  ));
}