How do you set a textInput to readOnly in Yii2?

Question

How do you set a textInput to readOnly? I have the sample code below:

<?= $form->field($model, 'GrossPay')->textInput(['id'=>'GrossPay','readonly'=> true])?>

Answer 1

It's readOnly not readonly but it does not make a difference here.

<?= $form->field($model, 'GrossPay')->textInput(['id'=>'GrossPay','readonly'=> true])?>