I have converted the postcode field in checkout to a dropdown field. Its working fine.
$fields['billing']['billing_postcode'] = array(
'type' => 'select',
'label' => __('Locality - Postcode', 'woocommerce'),
'placeholder' => _x('Select a locality', 'placeholder', 'woocommerce'),
'required' => true,
'class' => array('form-row-first'),
'clear' => false
);
This is getting updated in the db and values show on order invoice. Now how would I show the already stored value of postcode field as selected option in the checkout fields. For ex: How the name is auto populated for a registered customer based on his earlier order. I have tried a few functions, but no relief. Kindly advice somebody!