filter - How to get the size of a filtered (piped) set in angular2

Question

I wrote my own filter pipe as it disappeared in angular2:

import {Pipe, PipeTransform} from 'angular2/core';

@Pipe({
  name: 'myFilter'
})
export class MyFilter implements PipeTransform {
  transform(customerData: Array<Object>, args: any[]) {
    if (customerData == undefined) {
      return;
    }
    var re = new RegExp(args[0]);
    return customerData.filter((item) => re.test(item.customerId));
  }
}

And use it in my template:

<tr *ngFor="#singleCustomerData of customerData | myFilter:searchTerm">
  ...
</tr>

Now I'd like to see how many matches the pipe returns. So essentially the size of the returned array.

In angular 1.x we were able so assign the returned set to a variable in a template like so:

<div ng-repeat="person in filtered = (data | filter: query)">
</div>

But we can no longer assign variables in templates in angular2.

So how do I get the size of the filtered set without calling the filter twice?

Answer 1

You still must call the filter a second time but you can use it directly like this :

{{ (customerData | myFilter:searchTerm)?.length }}