Add custom register fields

addCustomregisterFields.php

<?php

/**
 * @snippet       Añadir campos al registro
 * @author        https://www.cloudways.com/blog/add-woocommerce-registration-form-fields/
 */
  
// 1. Add new register fields for WooCommerce registration.


function wooc_extra_register_fields() {?>
       <p class="form-row form-row-first">
	       <label for="reg_billing_first_name"><?php _e( 'First name', 'woocommerce' ); ?><span class="required">*</span></label>
	       <input type="text" class="input-text" name="billing_first_name" id="reg_billing_first_name" value="<?php if ( ! empty( $_POST['billing_first_name'] ) ) esc_attr_e( $_POST['billing_first_name'] ); ?>" />
       </p>
       <p class="form-row form-row-last">
	       <label for="reg_billing_last_name"><?php _e( 'Last name', 'woocommerce' ); ?><span class="required">*</span></label>
	       <input type="text" class="input-text" name="billing_last_name" id="reg_billing_last_name" value="<?php if ( ! empty( $_POST['billing_last_name'] ) ) esc_attr_e( $_POST['billing_last_name'] ); ?>" />
       </p>
       <p class="form-row form-row-last">
	       <label for="reg_billing_company"><?php _e( 'Empresa (Opcional)', 'woocommerce' ); ?></label>
	       <input type="text" class="input-text" name="billing_company" id="reg_billing_company" value="<?php if ( ! empty( $_POST['billing_company'] ) ) esc_attr_e( $_POST['billing_company'] ); ?>" />
       </p>
       <p class="form-row form-row-last">
	       <label for="reg_billing_cif"><?php _e( 'CIF/NIF (No incluya espacios ni guiones) ', 'woocommerce' ); ?><span class="required">*</span></label>
	       <input type="text" class="input-text" name="billing_cif" id="reg_billing_cif" value="<?php if ( ! empty( $_POST['billing_cif'] ) ) esc_attr_e( $_POST['billing_cif'] ); ?>" />
       </p>
       <p class="form-row form-row-wide">
	       <label for="reg_billing_phone"><?php _e( 'Phone', 'woocommerce' ); ?><span class="required">*</span></label>
	       <input type="text" class="input-text" name="billing_phone" id="reg_billing_phone" value="<?php esc_attr_e( $_POST['billing_phone'] ); ?>" />
       </p>
       <p class="form-row form-row-wide">
	       <label for="reg_billing_phone2"><?php _e( 'Teléfono 2', 'woocommerce' ); ?></label>
	       <input type="text" class="input-text" name="billing_phone2" id="reg_billing_phone2" value="<?php if ( ! empty( $_POST['billing_phone2'] ) ) esc_attr_e( $_POST['billing_phone2'] ); ?>" />
       </p>
       <p class="form-row form-row-wide">
	       <label for="reg_billing_address_1"><?php _e( 'Address', 'woocommerce' ); ?><span class="required">*</span></label>
	       <input type="text" class="input-text" name="billing_address_1" id="reg_billing_address_1" value="<?php esc_attr_e( $_POST['billing_address_1'] ); ?>" />
       </p>
       <p class="form-row form-row-wide">
	       <label for="reg_billing_city"><?php _e( 'City', 'woocommerce' ); ?><span class="required">*</span></label>
	       <input type="text" class="input-text" name="billing_city" id="reg_billing_city" value="<?php esc_attr_e( $_POST['billing_city'] ); ?>" />
       </p>
       <p class="form-row form-row-wide">
	       <label for="reg_billing_postcode"><?php _e( 'Postal Code', 'woocommerce' ); ?><span class="required">*</span></label>
	       <input type="text" class="input-text" name="billing_postcode" id="reg_billing_postcode" value="<?php esc_attr_e( $_POST['billing_postcode'] ); ?>" />
       </p>
       <div class="clear"></div>
       <?php

       //Dropdowns especiales
       wp_enqueue_script( 'wc-country-select' );

	   woocommerce_form_field( 'billing_country', array(
	        'type'      => 'country',
	        'class'     => array('chzn-drop'),
	        'label'     => __('Country'),
	        'placeholder' => __('Choose your country.'),
	        'required'  => true,
	        'clear'     => true
	    ));


	   wp_enqueue_script( 'wc-state-select' );

	   woocommerce_form_field( 'billing_state', array(
	        'type'      => 'state',
	        'class'     => array('chzn-drop'),
	        'label'     => __('Provincia'),
	        'placeholder' => __('Escoge tu provincia.'),
	        'required'  => true,
	        'clear'     => true
	    ));
 
 }

 add_action( 'woocommerce_register_form_start', 'wooc_extra_register_fields' );



//2. Validacion de los campos

function wooc_validate_extra_register_fields( $username, $email, $validation_errors ) {

      if ( isset( $_POST['billing_first_name'] ) && empty( $_POST['billing_first_name'] ) ) {
             $validation_errors->add( 'billing_first_name_error', __( '<strong>Error</strong>: Nombre es requerido', 'woocommerce' ) );
      }

      if ( isset( $_POST['billing_last_name'] ) && empty( $_POST['billing_last_name'] ) ) {
             $validation_errors->add( 'billing_last_name_error', __( '<strong>Error</strong>: Apellido es requerido', 'woocommerce' ) );
      }

      if ( isset( $_POST['billing_cif'] ) && empty( $_POST['billing_cif'] ) ) {
             $validation_errors->add( 'billing_cif_error', __( '<strong>Error</strong>: CIF es requerido', 'woocommerce' ) );
      }

      if ( isset( $_POST['billing_phone'] ) && empty( $_POST['billing_phone'] ) ) {
             $validation_errors->add( 'billing_phone_error', __( '<strong>Error</strong>: Telefono es requerido', 'woocommerce' ) );
      }

      if ( isset( $_POST['billing_address_1'] ) && empty( $_POST['billing_address_1'] ) ) {
             $validation_errors->add( 'billing_address_1_error', __( '<strong>Error</strong>: Dirección es requerido', 'woocommerce' ) );
      }

      if ( isset( $_POST['billing_city'] ) && empty( $_POST['billing_city'] ) ) {
             $validation_errors->add( 'billing_city_error', __( '<strong>Error</strong>: Ciudad es requerido', 'woocommerce' ) );
      }

      if ( isset( $_POST['billing_postcode'] ) && empty( $_POST['billing_postcode'] ) ) {
             $validation_errors->add( 'billing_postcode_error', __( '<strong>Error</strong>: Código postal es requerido', 'woocommerce' ) );
      }

     return $validation_errors;
}

add_action( 'woocommerce_register_post', 'wooc_validate_extra_register_fields', 10, 3 );


//3. Insertar datos en la database

function wooc_save_extra_register_fields( $customer_id ) {

      if ( isset( $_POST['billing_phone'] ) ) {
                 // Phone input field which is used in WooCommerce
                 update_user_meta( $customer_id, 'billing_phone', sanitize_text_field( $_POST['billing_phone'] ) );
      }

      if ( isset( $_POST['billing_phone2'] ) ) {
        // Phone2 input field which is used in WooCommerce
        update_user_meta( $customer_id, 'billing_phone2', sanitize_text_field( $_POST['billing_phone2'] ) );
}

	  if ( isset( $_POST['billing_first_name'] ) ) {
	         //First name field which is by default
	         update_user_meta( $customer_id, 'first_name', sanitize_text_field( $_POST['billing_first_name'] ) );
	         // First name field which is used in WooCommerce
	         update_user_meta( $customer_id, 'billing_first_name', sanitize_text_field( $_POST['billing_first_name'] ) );
	  }

	  if ( isset( $_POST['billing_last_name'] ) ) {
	         // Last name field which is by default
	         update_user_meta( $customer_id, 'last_name', sanitize_text_field( $_POST['billing_last_name'] ) );
	         // Last name field which is used in WooCommerce
	         update_user_meta( $customer_id, 'billing_last_name', sanitize_text_field( $_POST['billing_last_name'] ) );
	  }

	  if ( isset( $_POST['billing_company'] ) ) {
                 update_user_meta( $customer_id, 'billing_company', sanitize_text_field( $_POST['billing_company'] ) );
      }

      if ( isset( $_POST['billing_cif'] ) ) {
                 update_user_meta( $customer_id, 'billing_cif', sanitize_text_field( $_POST['billing_cif'] ) );
      }

      if ( isset( $_POST['billing_address_1'] ) ) {
                 update_user_meta( $customer_id, 'billing_address_1', sanitize_text_field( $_POST['billing_address_1'] ) );
      }

      if ( isset( $_POST['billing_city'] ) ) {
                 update_user_meta( $customer_id, 'billing_city', sanitize_text_field( $_POST['billing_city'] ) );
      }

      if ( isset( $_POST['billing_postcode'] ) ) {
                 update_user_meta( $customer_id, 'billing_postcode', sanitize_text_field( $_POST['billing_postcode'] ) );
      }

      if ( isset( $_POST['billing_country'] ) ) {
                 update_user_meta( $customer_id, 'billing_country', sanitize_text_field( $_POST['billing_country'] ) );
      }

      if ( isset( $_POST['billing_state'] ) ) {
                 update_user_meta( $customer_id, 'billing_state', sanitize_text_field( $_POST['billing_state'] ) );
      }
}
add_action( 'woocommerce_created_customer', 'wooc_save_extra_register_fields' );