Angular Pipe chaining on a element does not work

Question

I have created a filter and sort pipes in Angular and chained it as below. But the pipe chaining is not working. If I use only a single pipe it works but if I use two pipes like below only the filter functionality works sort pipe does not work. Can somebody tell me what is the mistake that I am doing?

      <div class="grid-container">
        <div class="grid-item" *ngFor="let prod of (productsList.products | sort:sortProductSelected | filterOnPrice:priceRange )">
          <div class="card" style="width: 18rem;border: 0px;">
            <img src="{{prod.thumbnail}}" class="card-img-top" alt="...">
            <div class="card-body">
              <h5 class="card-title">{{prod.brand}}</h5>
              <p class="card-text">${{prod.price}}</p>
              <p class="card-text">{{prod.description}}</p>
              <a target="_blank" class="btn btn-primary" (click)="viewProduct(prod.id)">View Product</a>
            </div>
          </div>
        </div>
      </div>
    </div>
    

Sort pipe

export class SortPipe implements PipeTransform {
  transform(value: any[], ...args: any): any[] {
    if(args){
      switch(args[0]){
        case 'Price low to hight': 
          value.sort((a,b)=>{
            if(a.price<b.price) return  -1;
            else if(a.price>b.price) return 1;
          return 0;
          console.log("value");

          })
          break;
        case 'Price High to Low' :
          value.sort((a,b)=>{
            if(a.price>b.price) return  -1;
            else if(a.price<b.price) return 1;
          return 0;
          })
          break;
        case 'Ratings':
          value.sort((a,b)=>{
            if(a.rating<b.rating) return  -1;
            else if(a.rating>b.rating) return 1;
          return 0;
          })
          break;
        case 'Discounts' :
          value.sort((a,b)=>{
            if(a.discountPercentage<b.discountPercentage) return  -1;
            else if(a.discountPercentage>b.discountPercentage) return 1;
          return 0;
          })
          break;
        default: return value;
      }  
    }

    return value;
  }

}

Filter Pipe

export class FilterOnPricePipe implements PipeTransform {
  transform(value: any[], ...args: any): any[] {
    let FliteredArray:any[] =[];

    FliteredArray = value.filter((a)=>{
           console.log(a.price);
           console.log(FliteredArray);
      return a.price<=args[0];

    })
    console.log(FliteredArray);
    return FliteredArray;
  }

}

Answer 1

Its best to use the filterPipe first then perform the sortPipe when I did this it worked fine, since we are removing the unnecessary values and sorting it will improve the performance!

Also I guess the input reference did not change so you were getting this issue!

Because when I changed the line 45 in sortPipe it started working fine (without swapping the pipes), so I guess the reference of the array needs to be updated for the pipe to be triggered.

return [...value];

I think you should perform the filter first and then sort, since its makes sense and no need to update the reference!

Below is a working example!

ts

import { CommonModule } from '@angular/common';
import { Component } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { bootstrapApplication } from '@angular/platform-browser';
import 'zone.js';
import { FilterOnPricePipe } from './filter.pipe';
import { SortPipe } from './sort.pipe';

@Component({
  selector: 'app-root',
  standalone: true,
  imports: [CommonModule, FilterOnPricePipe, SortPipe, FormsModule],
  template: `
  sortProductSelected
  <select [(ngModel)]="sortProductSelected">
        <option *ngFor="let state of states" [ngValue]="state.name">
          {{ state.name }}
        </option>
      </select><br/>
      <input type="number" [(ngModel)]="priceRange"/>
  <div class="grid-container">
     <div class="grid-item" *ngFor="let prod of (productsList.products | filterOnPrice:priceRange | sort:sortProductSelected )">
       <div class="card" style="width: 18rem;border: 0px;">
         <img src="{{prod.thumbnail}}" class="card-img-top" alt="..."/>
         <div class="card-body">
           <h5 class="card-title">{{prod.brand}}</h5>
           <p class="card-text">$ {{prod.price}}</p>
           <p class="card-text">{{prod.description}}</p>
           <a target="_blank" class="btn btn-primary" (click)="viewProduct(prod.id)">View Product</a>
         </div>
       </div>
     </div>
   </div>  
   `,
})
export class App {
  states = [
    { name: 'Price low to hight' },
    { name: 'Price High to Low' },
    { name: 'Ratings' },
    { name: 'Discounts' },
  ];
  sortProductSelected = 'Price low to hight';
  priceRange = 15;
  name = 'Angular';
  productsList = {
    products: [
      {
        thumbnail: 'https://placehold.co/600x400',
        brand: 'test',
        price: 1,
        rating: 1,
        discountPercentage: 1,
        description: 'test',
        id: 1,
      },
      {
        thumbnail: 'https://placehold.co/600x400',
        brand: 'test',
        price: 2,
        rating: 2,
        discountPercentage: 2,
        description: 'test',
        id: 2,
      },
      {
        thumbnail: 'https://placehold.co/600x400',
        brand: 'test',
        price: 3,
        rating: 3,
        discountPercentage: 3,
        description: 'test',
        id: 3,
      },
    ],
  };

  viewProduct(e: any) {}
}

bootstrapApplication(App);

stackblitz