How to add Row after every 3 columns in angular - html

Question

What i am trying to do is add a row div after every 3 colum divs
Example Output need:
<div class="row">
<div class="col-md-6"></div>
<div class="col-md-6"></div>
<div class="col-md-6"></div>
</div>
I have an array of products i am iltrating like this
<div class="row" *ngFor="let p of relatedProperties;let i = index">
<div class="col-md-6" *ngIf="relatedProperties[i].title !== undefined">{{ relatedProperties[i].title }}</div>
<div class="col-md-6" *ngIf="relatedProperties[i].title !== undefined">{{ relatedProperties[i].title }}</div>
<div class="col-md-6" *ngIf="relatedProperties[i].title !== undefined">{{ relatedProperties[i].title }}</div>
</div>
But the problem is that my every row prints same title on one iltration and second on next iltration
Current output
<div class="row">
<div class="col-md-6">Title1</div>
<div class="col-md-6">Title1</div>
<div class="col-md-6">Title1</div>
</div>
<div class="row">
<div class="col-md-6">Title2</div>
<div class="col-md-6">Title2</div>
<div class="col-md-6">Title2</div>
</div>
<div class="row">
<div class="col-md-6">Title3</div>
<div class="col-md-6">Title3</div>
<div class="col-md-6">Title3</div>
</div>
Desired Output
<div class="row">
<div class="col-md-6">Title1</div>
<div class="col-md-6">Title2</div>
<div class="col-md-6">Title3</div>
</div>
<div class="row">
<div class="col-md-6">Title4</div>
<div class="col-md-6">Title5</div>
<div class="col-md-6">Title6</div>
</div>
<div class="row">
<div class="col-md-6">Title7</div>
<div class="col-md-6">Title8</div>
<div class="col-md-6">Title9</div>
</div>

Answer 1

If you split your Array into subarrays with always 3 titel's then you can easy loop through this Array in your template.
https://ng-run.com/edit/zZsztdvTOTpzbUC5Buuj?open=app%2Fapp.component.ts
component html
<div class="row" *ngFor="let row of newTitleArr; let i = index">
<div class="col" *ngFor="let col of newTitleArr[i]">{{ col.title }}</div>
</div>
component ts
import { Component, OnInit } from '#angular/core';
#Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
titleArr = [
{ title: 'title1' },
{ title: 'title2' },
{ title: 'title3' },
{ title: 'title4' },
{ title: 'title5' },
{ title: 'title6' },
{ title: 'title7' },
{ title: 'title8' },
{ title: 'title9' },
{ title: 'title10' },
{ title: 'title11' },
{ title: 'title12' },
{ title: 'title13' },
];
newTitleArr:any[];
ngOnInit() {
this.newTitleArr = this.splitArr(this.titleArr, 3)
}
splitArr(arr, size) {
let newArr = [];
for(let i = 0; i< arr.length; i += size) {
newArr.push(arr.slice(i, i+size));
}
return newArr;
}
}

Answer 2

Maybe this works, but Im unsure
<ng-container *ngFor="let p of relatedProperties; let i = index">
<div class="row" *ngIf="(i + 1) / 3 === 1">
<div class="col-md-6" *ngIf="relatedProperties[i - 2].title != null">{{ relatedProperties[i].title }}</div>
<div class="col-md-6" *ngIf="relatedProperties[i - 1].title != null">{{ relatedProperties[i].title }}</div>
<div class="col-md-6" *ngIf="relatedProperties[i].title != null">{{ relatedProperties[i].title }}</div>
</div>
</ng-container>
Also, I gotta say this feels pretty hacky, but if this is what you request, this should work
edit:
Note that strict null (a == null) is better than checking for undefined (a === undefined), as it will check for both undefined or null. In your case title != null.
Also, you could build an iterable that holds the structure you want in a cleaner way.
instead of having [title1, title2, title3, title4, title5, title6...] you should try to have [[title1, title2, title3], [title4, title5, title6], ...] which is way cleaner and allows you to simply have two *ngFors inside your template
<element1 *ngFor="let innerArray of myArray; let i = index">
<element2 *ngFor="let title of innerAray; let j = index">
</element2>
</element1>
And finally, I suggest you avoid calling a variable 'p', that's bad practice.

Answer 3

You can use this to add a row after every 3 columns.
<ng-container *ngFor="let p of relatedProperties; let i = index">
<div class="row" *ngIf="(i%3)==0">
<div class="col-md-6" *ngFor="let p of relatedProperties.slice(i, i+3)>
<span *ngIf="relatedProperties[i].title !== undefined"> {{ relatedProperties[i].title }} </span>
</div>
</div>
</ng-container>