How to make a form field required in WooCommerce checkout - php

Question

In the Checkout form I created a select field. My question is how in Wordpress or Woocmmerce this camp can be left as required.
<p class="form-row form-row-wide validate-required validate-region" id="shipping_region_field" data-priority="6">
<select name="shipping_region" id="shipping_region" class="state_select select2-selection--single" autocomplete="address-level1" data-placeholder="" tabindex="-1" aria-hidden="true">
<option>Opción 01</option>
<option>Opción 02</option>
</select>
</p>

Answer 1

1) For normal or custom billing and shipping fields you can use woocommerce_billing_fields or woocommerce_shipping_fields action hooks on checkout page as follow.
It will make a custom checkout field required without any need to add a validation script and to save it in the order. The field will also appear in My account edit adresses field section.
Some argument explanations:
The class 'update_totals_on_change' allow to trigger "update checkout" on change.
The 'required' attribute make the field required or not
The 'priority' attribute allow you to change the location of the field.
The code:
add_filter( 'woocommerce_shipping_fields', 'display_shipping_region_checkout_field', 20, 1 );
function display_shipping_region_checkout_field( $fields ) {
$fields['shipping_region'] = array(
'type' => 'select',
'label' => __("Region", "woocommerce") ,
'class' => array('form-row-wide', 'update_totals_on_change'),
'required' => true,
'options' => array(
'' => __("Choose a region please"),
'option-1' => __("Option 01"),
'option-2' => __("Option 02"),
'option-3' => __("Option 03"),
),
'priority' => 100,
'clear' => true,
);
return $fields;
}
Code goes in function.php file of your active child theme (or active theme). Tested and works.
2) In specific cases you need to use the woocommerce_default_address_fields filter. This filter is applied to all billing and shipping default fields *(see the documentation). It's used only some default checkout fields.
3) You can also use woocommerce_checkout_fieldsthat has $fields as function argument (see documentation).
4) For other custom checkout fields you can use one of the following hooks with the woocommerce_form_field() function:
woocommerce_before_checkout_billing_form has $checkout as function argument
woocommerce_before_checkout_billing_form has $checkout as function argument
woocommerce_before_checkout_shipping_form has $checkout as function argument
woocommerce_before_checkout_shipping_form has $checkout as function argument
woocommerce_before_order_notes has $checkout as function argument
woocommerce_after_order_notes has $checkout as function argument
The code that display the field, validate the field and save the field in the order:
// Display field
add_action( 'woocommerce_after_checkout_shipping_form', 'display_shipping_region_after_checkout_shipping_form', 10, 1 );
function display_shipping_region_after_checkout_shipping_form ( $checkout ) {
woocommerce_form_field( 'shipping_region', array(
'type' => 'select',
'label' => __("Region", "woocommerce") ,
'class' => array('form-row-wide','update_totals_on_change'),
'required' => true,
'options' => array(
'' => __("Choose a region please"),
'option-1' => __("Option 01"),
'option-2' => __("Option 02"),
'option-3' => __("Option 03"),
),
'priority' => 100,
'clear' => true,
), $checkout->get_value( 'shipping_region' ) );
}
// Field Validation
add_action('woocommerce_checkout_process', 'shipping_region_custom_checkout_field_validation');
function shipping_region_custom_checkout_field_validation() {
if ( isset($_POST['shipping_region']) && empty($_POST['shipping_region']) )
wc_add_notice( __( 'Please select something into Region field.' ), 'error' );
}
// Save Field value
add_action( 'woocommerce_checkout_create_order', 'action_checkout_create_order_callback', 10, 2 );
function action_checkout_create_order_callback( $order, $data ) {
if ( isset($_POST['shipping_region']) && empty($_POST['shipping_region']) ) {
$order->update_meta_data( '_shipping_region', esc_attr($_POST['shipping_region']) );
if( $order->get_user_id() > 0 )
update_user_met( $order->get_user_id(), 'shipping_region', esc_attr($_POST['shipping_region']) );
}
}
Code goes in function.php file of your active child theme (or active theme). Tested and works.
WooCommerce Documentation: Customizing checkout fields using actions and filters

Answer 2

you can add an attribute to the select tag
<select required name="shipping_region" id="shipping_region" class="state_select select2-selection--single" autocomplete="address-level1" data-placeholder="" tabindex="-1" aria-hidden="true">
<option>Opción 01</option>
<option>Opción 02</option>
</select>

Answer 3

**If You Have Created Your Custom Field at the checkout page**
add_action( 'woocommerce_after_checkout_validation', 'shipping_time_optionss', 9999, 2);
function shipping_time_optionss( $fields, $errors ){
// if any validation errors
if ( empty( $_POST['woo_shipping_time'] ) ) {
$errors->add( 'woocommerce_password_error', __( 'Please Select Shipping Time Option.' ) );
}
}

Answer 4

**
If You Have Created Your Custom Field at the checkout page
**
add_action( 'woocommerce_after_checkout_validation', 'shipping_time_optionss', 9999, 2);
function shipping_time_optionss( $fields, $errors ){
// if any validation errors
if ( empty( $_POST['woo_shipping_time'] ) ) {
$errors->add( 'woocommerce_password_error', __( 'Please Select Shipping Time Option.' ) );
}
}