I want the radio button preselected in my form.
<?= $form->field($model, 'config')->radioList(['1'=>'Automatic Entry',2=>'Manual Entry'])
->label('Barcode/Book No Generation'); ?>
The preselected values are taken from $model->config
. That means that you should set that attribute to the value that you want preselected :
$model->config = '1';
$form->field($model, 'config')->radioList([
'1' => 'Automatic Entry',
'2' => 'Manual Entry',
]);
The relevant doc for this is in the ActiveForm class.