Populate external drop downs for datatable filtering

index.blade.php

<!-- Holder div for filter select boxes -->
<div id="table_filters" class="form-row"></div>

<table class='table datatable' id="registrations">
  <thead class='thead-light'>
    <tr>
      <th>Product</th>
      <th>Type</th>
      <th>Status</th>
      <th>Registration Date</th>
      <th>Renewal Date</th>
    </tr>
  </thead>
  <tbody>
  </tbody>
</table>

<script type="text/javascript">
  $(document).ready(function() {
    $("#registrations").dataTable( {
      "ajax": '{!! route('ajax.registrations') !!}',
      processing: true,
      serverSide: true,
      columns: [
        {data: "product.name"},
        {data: "reg_type.type"},
        {data: "status"},
        {data: "reg_date"},
        {data: "renew_date"},
      ],
      initComplete: function (settings, json) {
        this.api().columns([0,2,3]).every( function () {
          var column = this;
          // Use column title as label for select
          var title = $(column.header()).text();
          
          // Generate Label
          var label = $('<div class="col-md-3"><label>'+title+'</label></div>').appendTo($("#table_filters"));
          
          // Generate select
          var select = $('<select class="form-control"><option value="">Show All</option></select>')
            .appendTo( label )
            // Search when selection is changed
            .on( 'change', function () {
              var val = $(this).val();
              column.search( this.value ).draw();
            } );

          // Capture the data from the JSON to populate the select boxes with all the options
          var extraData = (function(i) {
            switch(i) {
            case 0:
              return json.allProducts;
            case 2:
              return json.allTypes;
            case 3:
              return json.allStatus;
            }
          })(column.index());

          // Draw select options
          extraData.forEach( function ( d ) {
            if(column.search() === d){
              select.append( '<option value="'+d+'" selected="selected">'+d+'</option>' )
            } else {
              select.append( '<option value="'+d+'">'+d+'</option>' )
            }
          } );
        } );
      }
    });
  });
</script>

RegistrationController.php

/**
 * Process datatables ajax request.
 *
 * @return \Illuminate\Http\JsonResponse
 */
public function allData(Request $request)
{
  $registrations = Registration::with('product')->with('reg_type')->select('registrations.*');

  $datatable = Datatables::of($registrations);
  
  if($request->draw == 1) {
    $products = \App\Product::active()->distinct('name')->pluck('name');
    $types = \App\RegType::active()->distinct('type')->pluck('type');
    $status = Registration::distinct('status')->pluck('status');
    $datatable->with([
      'allProducts' => $products,
      'allTypes' => $types,
      'allStatus' => $status,
    ]);
  }

  return $datatable->make(true);

}

web.php

Route::group(['prefix' => 'ajax'], function() {
	Route::get('registrations', 'RegistrationController@allData')->name('ajax.registrations');
});