Filter piping on the list

[thethakuri]

REQUIRED: Before filing a bug report

Change each [ ] to [x] when you have done it.

• [x ] My issue title starts with using pipes to filter the list
• [x ] I have read the README, especially the 'classic blunders' section, and the dragula docs.
• [x ] I have searched through the ng2-dragula issues for related problems, including closed issues.
• [x ] I have browsed through the issues labeled "future reference" for problems that have been solved before or have a known workaround.
• [ x] I am using the latest version of ng2-dragula.

Describe the bug (required)

I have created a search filter pipe that filters the list of items in the container. Once I filter and drag and drop the item, looks like the actualy index of the item doesn't change. For e.g. if the list contains ['foo','bar'] and I filter for 'bar' and drag and drop, I get 'foo'. So it seems the index of the current item (e.g. 0) is still reference to the unfiltered list ['foo','bar'].

To Reproduce (required)

Steps to reproduce the behavior:

1. Create a simple search filter such as:

import { Pipe, PipeTransform } from '@angular/core';
@Pipe({
  name: 'searchFilter'
})
export class SearchFilterPipe implements PipeTransform {

  transform(value: any, args?: any): any {
    if(!value) return null;
    if(!args) return value;

    args = args.toLowerCase();

    return value.filter(function(data: any){
      return JSON.stringify(data).toLowerCase().includes(args);
    });
  }
}

2. Apply it to the DOM element like this

<div id="group-source" [dragula]="'GROUPS_CONTAINER'" [(dragulaModel)]="group_names">
    <span *ngFor="let group_name of group_names | searchFilter: query">{{group_name}}</span>
</div>

3. Filter list
4. See error

Screenshots (optional)

If applicable, add screenshots to help explain your problem.

Versions (required)

Please state which versions of the following packages you have installed:
"ng2-dragula": "^2.1.1"

[thethakuri]

I've worked around this by aplying a class that essentially changes the style to display:none