Using dynamic pipes within an ngFor loop in Angular 2

I am currently programming an Angular4 application and facing a challenge with how to handle an array that contains values along with their corresponding pipe types (regions, language or number).

const values = [
   { value: 'us', pipe: 'regions'},
   { value: 'en', pipe: 'language'},
   { value: '100', pipe: 'number'},
.....
];

I need to use ngFor to display the values while applying the correct pipes. Here's what I've tried:

<li *ngFor="let item of values"> {{item.value | item.pipe}} </li>

I attempted to create a class called FacetConfiguration and inject the pipe object into it, but this approach did not work as expected.

Is there a better way to achieve this? Any other ideas would be greatly appreciated.

P.S. I have a large list of configurations, each requiring a different pipe type, so hard coding them all would be quite challenging.

Thank you!

Answer №1

If you're looking to streamline your pipe application process, consider implementing a main pipe that dynamically selects which specific pipe to use based on the input value:

Here's an example of how you can set up your main pipe and transform function:

const values = [
   { value: 'us', pipe: new RegionPipe},
   { value: 'en', pipe: new LanguagePipe},
   { value: '100', pipe: new NumberPipe},
.....
];

trasform(value): any {
   for(let val of values) {
      if(val.value === value) {
          return val.pipe.transform(value);
      }
   }
   return '';
}

In addition, you have the option to pass another pipe as a parameter to your main pipe. Here's how you can set it up in your component:

@Component({
  selector: 'my-app',
  template: `
    <div>
      <h2>{{'some text'| main: test}}</h2>
    </div>
  `,
})
export class App {
  name: string;
  test = new TestPipe;
  constructor() {

  }
}

@Pipe({name: 'main'})
export class MainPipe implements PipeTransform {
  transform(value: any, p: any): any {
    return p.transform(value);
  }
}

@Pipe({name: 'test'})
export class TestPipe implements PipeTransform {
  transform(value: any): any {
    return 'test';
  }
}

Answer №2

Check out the provided Sample Pipe implementation below:

import { Pipe, PipeTransform } from '@angular/core';

import { IProduct } from '../products/product';
@Pipe({

  name:'productFilter'
})
export class ProductFilterPipe implements PipeTransform{

  transform(value: IProduct[], filterBy: string): IProduct[] {
      filterBy = filterBy ? filterBy.toLowerCase() : null;
      return filterBy ? value.filter((product: IProduct) =>
          product.productName.toLowerCase().indexOf(filterBy) !== -1) : value;
  }


}

Look at how it is used in HTML:

  <tr *ngFor='let product of products|productFilter:listFilter'>

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