Yii2: How do I pass a PHP variable that is assigned in Grid table to a Modal?

Question

I have an issue that I have to retrieve the PHP Variable from the Grid to the Modal.

The situation is like this:

This is one of my columns which I name as 'flag', there is a condition state in the column that when the row contains 'test', the column will output a button.

[
                'headerOptions' => ['style' => 'text-align: center; width: 3%; vertical-align: middle;'],
                'contentOptions' => ['style' => 'text-align: center;'],
                'attribute'=>'flag',
                'format'=>'raw',
                'value'=>function($model){
                    // $result = $model->flag?
                    $getCode = $model->customer_code;

                    $getBillID = CustomerBillingParty::find()->select('id')->where(['customer_code'=>$getCode])->scalar();

                    $getMain = CustomerBillingParty::find()->select('to_main')->where(['id'=>$getBillID])->scalar();
                    $getbillto = CustomerBillingParty::find()->select('bill_to')->where(['id'=>$getBillID])->scalar();
                    $getbilladdress = CustomerBillingParty::find()->select('billing_address')->where(['id'=>$getBillID])->scalar();
                    
                    if($model->change_billing_party =="TEST")
                    {
                        $result= HTML::SubmitButton('ALERT',['name'=>'fname','value'=>$getCode,'id'=>'btnclickvalue','bill_address'=>$getbilladdress,'bill_to'=>$getbillto,'BillID'=>$getBillID,'To_Main'=>$getMain,'sspc_ref'=>$getSSPC,'customer_code'=>$getCode,'class'=>'twelve btn-new-billing'],['data-method' =>'POST']);
                  
                    }
                    else{
                        $result="N/A";
                    }
                    return $result;
                } 
            ],

The button contains a class that will output a Modal when clicked. This is performed by using javascript/jquery to show the modal.

$(document).on('click','.btn-new-billing',function(){
    $('#modal-new-billingParty').modal('show');

    $('#customerbillingparty-customer_code').val($(this).attr('customer_code'));
    $('#customerbillingparty-to_main').val($(this).attr('to_main'));
    $('#customerbillingparty-bill_to').val($(this).attr('bill_to'));
    $('#customerbillingparty-billing_address').val($(this).attr('bill_address'));
    //The 4 lines above are used to populate the form inside the Modal based on the row on the Grid.
});

The button also contains a set of attributes that carries a value to be used inside of a Modal.

I need to pass the value of the button when clicked in the Modal.

This is the modal code (The modal code is coded above the GRID): The modal is pop out when the button is clicked using the javascript/jquery.

Modal::begin([
    'header' => 'Billing Party',
    'id'=>'modal-new-billingParty',
    'size'=>'modal-lg',
]);

    
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // collect value of input field
    $name = $_POST['fname'];
    if (empty($name)) {
        echo "EMPTY";
    } else {
        echo "HELOOOOOOOOOOOOOOOOO";
    }
}

  //echo "HELLOOOOO";
   
    echo    '<div class="customer-billing-party-form">';

    $form = ActiveForm::begin([

        'action' =>['customer-billing-party/create']
    ]);

    echo    $form->field($modelBill, 'customer_code')->textInput(['maxlength' => true,'readonly'=>true]);

 
        echo    $form->field($modelBill, 'to_main')->dropDownList(
        
       ArrayHelper::map(CustomerBillingParty::find()->where(['id'=>***NEED TO PASS VALUE HERE***])->all(),'id','to_main'),
   
        [
           'prompt'=>'-Select To Main-',
        ]
    );


    //echo    $form->field($modelBill, 'to_main')->textInput(['maxlength' => true]);
    //$form->field($modelBill, 'to_main')->textInput(['maxlength' => true]);

    echo    $form->field($modelBill, 'bill_to')->textInput(['maxlength' => true,'readonly'=>true]);

    echo    $form->field($modelBill, 'billing_address')->textInput(['maxlength' => true,'readonly'=>true]);

    echo    '<div class="form-group">';
    echo        Html::submitButton(Yii::t('app', 'Save'), ['class' => 'btn btn-success']);
    echo    '</div>';

    ActiveForm::end();

    echo    '</div>';

Modal::end();

This Modal is an input form that will pop out of the screen when the button is clicked.

The issue is that I need to pass the PHP variable inside the Grid view which is $getCode to the Modal. I need to pass the value in the dropdownlist in the Modal.

You can see the note 'NEED TO PASS VALUE HERE'

How do I solve this issue?