Angular 2 - ngFor雖然索引<x

Question

我目前正在研究項目（對象）數組的角度應用程序。我想在它自己的列表項中顯示數組中的每個對象，但是想要將列表的高度限制爲9行，然後在它旁邊的新列表上開始。所以如果數組有13個元素，array [0]到array [8]應該列在第一列中的第一列中，而array [9]到array [12]列在新列表中。 如何使* ngFor在index = 9處停止循環，並從另一個列表中開始循環？

這是我當前的代碼的外觀：

<div *ngIf="patients" class="col-sm-4" id="patientList"> 

    <!--Patient 0 to 8 should go in this space--> 

    <table id="patientsTab"> 
    <tr *ngFor="let patient of patients; let i = index;" class="patientRow" > 
     <td class="ptName"><button class="patientSelect" (click)="selectPatient(i)" >{{ patient.firstName }} {{ patient.lastName }}</button></td> 
     <td class="ptPersonnr">{{ patient.personnr }}</td> 
    </tr> 
    </table> 
</div> 

<div *ngIf="patients.length > 9" class="col-sm-4"> 

    <!--Patient 9 to 13 should go in this space--> 

</div> 

<div *ngIf="patient" class="col-sm-4"> 

</div> 

Answer 1

你可以這樣做：

get slicedList(){ 
    return this.sliceList(this.patients,9); 
} 

private sliceList(list: string[], factor: number): string[][] { 
    const result: string[][] = []; 
    const totalIterations = Math.max(Math.ceil(list.length/factor),1); 
    let iteration = 0; 

    while (totalIterations > iteration) { 
     const start = iteration * factor; 
     const end = Math.min((iteration + 1) * factor, list.length); 
     result.push(list.slice(start, end)); 
     iteration++; 
    } 
    return result; 
    } 

模板：

這樣的

<ng-container *ngFor="let sublist of slicedList;index as listIndex"> 
    // sublist is a list of size N, with N <= 9 
    List: {{i+1}} 
    <ng-container *ngFor="let patient of sublist; index as patientIndex"> 
     {{patient | json}} 
     <span>Patient at index: {{(listIndex*9)+patientIndex}}</span> 
    </ng-container> 
</ng-container> 

Answer 2

一種方法是使用Array.prototype.slice方法：

<div *ngIf="patients" class="col-sm-4" id="patientList"> 

    <!--Patient 0 to 8 should go in this space--> 

    <table id="patientsTab"> 
    <tr *ngFor="let patient of patients.slice(0, 8); let i = index;" class="patientRow" > 
     <td class="ptName"><button class="patientSelect" (click)="selectPatient(i)" >{{ patient.firstName }} {{ patient.lastName }}</button></td> 
     <td class="ptPersonnr">{{ patient.firstName }}</td> 
    </tr> 
    </table> 
</div> 

<div *ngIf="patients.length > 9" class="col-sm-4"> 
    <div *ngFor="let patient of patients.slice(8, 13);"> 
    {{ patient.firstName }} 
    </div> 
</div> 

Stackblitz Example

Answer 3

除了@ yurzui的回答，您可以使用角管

Stackblitz Example

import { Pipe, PipeTransform } from '@angular/core'; 
@Pipe({name: 'stopat'}) 
export class StopAtPipe implements PipeTransform { 
    transform(value: Array<any>, start:number, end:number) {  
    return value.slice(start,end); 
    } 
} 

<div class="container"> 
    <div class="row"> 
    <div *ngIf="patients" class="col-sm-4" id="patientList"> 

     <!--Patient 0 to 8 should go in this space--> 

     <table id="patientsTab"> 
     <tr *ngFor="let patient of patients | stopat:0:8; let i = index;" class="patientRow" > 
      <td class="ptName"><button class="patientSelect" (click)="selectPatient(i)" >{{ patient.firstName }} {{ patient.lastName }}</button></td> 
      <td class="ptPersonnr">{{ patient.firstName }}</td> 
     </tr> 
     </table> 
    </div> 

    <div *ngIf="patients.length > 9" class="col-sm-4"> 
     <div *ngFor="let patient of patients | stopat:8:13;"> 
     {{ patient.firstName }} 
     </div> 
    </div> 

    <div *ngIf="patient" class="col-sm-4"> 

    </div> 
    </div> 

</div>