WooCommerce : add custom fields to product variations v2.0

gistfile1.php

<?php

//Display Fields
add_action( 'woocommerce_product_after_variable_attributes', 'variable_fields', 10, 3 );
//JS to add fields for new variations
add_action( 'woocommerce_product_after_variable_attributes_js', 'variable_fields_js' );
//Save variation fields
add_action( 'woocommerce_save_product_variation', 'save_variable_fields', 10, 1 );

/**
 * Create new fields for variations
 *
*/
function variable_fields( $loop, $variation_data, $variation ) {
?>
	<tr>
		<td>
			<?php
			// Text Field
			woocommerce_wp_text_input( 
				array( 
					'id'          => '_text_field['.$loop.']', 
					'label'       => __( 'My Text Field', 'woocommerce' ), 
					'placeholder' => 'http://',
					'desc_tip'    => 'true',
					'description' => __( 'Enter the custom value here.', 'woocommerce' ),
					'value'       => get_post_meta($variation->ID, '_text_field'], true)
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Number Field
			woocommerce_wp_text_input( 
				array( 
					'id'          => '_number_field['.$loop.']', 
					'label'       => __( 'My Number Field', 'woocommerce' ), 
					'desc_tip'    => 'true',
					'description' => __( 'Enter the custom number here.', 'woocommerce' ),
					'value'       => get_post_meta($variation->ID, '_number_field'], true),
					'custom_attributes' => array(
									'step' 	=> 'any',
									'min'	=> '0'
								) 
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Textarea
			woocommerce_wp_textarea_input( 
				array( 
					'id'          => '_textarea['.$loop.']', 
					'label'       => __( 'My Textarea', 'woocommerce' ), 
					'placeholder' => '', 
					'description' => __( 'Enter the custom value here.', 'woocommerce' ),
					'value'       => get_post_meta($variation->ID, '_textarea'], true)
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Select
			woocommerce_wp_select( 
			array( 
				'id'          => '_select['.$loop.']', 
				'label'       => __( 'My Select Field', 'woocommerce' ), 
				'description' => __( 'Choose a value.', 'woocommerce' ),
				'value'       => get_post_meta($variation->ID, '_select'], true),
				'options' => array(
					'one'   => __( 'Option 1', 'woocommerce' ),
					'two'   => __( 'Option 2', 'woocommerce' ),
					'three' => __( 'Option 3', 'woocommerce' )
					)
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Checkbox
			woocommerce_wp_checkbox( 
			array( 
				'id'            => '_checkbox['.$loop.']', 
				'label'         => __('My Checkbox Field', 'woocommerce' ), 
				'description'   => __( 'Check me!', 'woocommerce' ),
				'value'         => get_post_meta($variation->ID, '_checkbox'], true)
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Hidden field
			woocommerce_wp_hidden_input(
			array( 
				'id'    => '_hidden_field['.$loop.']', 
				'value' => 'hidden_value'
				)
			);
			?>
		</td>
	</tr>
<?php
}

/**
 * Create new fields for new variations
 *
*/
function variable_fields_js() {
?>
	<tr>
		<td>
			<?php
			// Text Field
			woocommerce_wp_text_input( 
				array( 
					'id'          => '_text_field[ + loop + ]', 
					'label'       => __( 'My Text Field', 'woocommerce' ), 
					'placeholder' => 'http://',
					'desc_tip'    => 'true',
					'description' => __( 'Enter the custom value here.', 'woocommerce' ),
					'value'       => ''
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Number Field
			woocommerce_wp_text_input( 
				array( 
					'id'                => '_number_field[ + loop + ]', 
					'label'             => __( 'My Number Field', 'woocommerce' ), 
					'desc_tip'          => 'true',
					'description'       => __( 'Enter the custom number here.', 'woocommerce' ),
					'value'             => '',
					'custom_attributes' => array(
									'step' 	=> 'any',
									'min'	=> '0'
								) 
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Textarea
			woocommerce_wp_textarea_input( 
				array( 
					'id'          => '_textarea[ + loop + ]', 
					'label'       => __( 'My Textarea', 'woocommerce' ), 
					'placeholder' => '', 
					'description' => __( 'Enter the custom value here.', 'woocommerce' ),
					'value'       => '',
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Select
			woocommerce_wp_select( 
			array( 
				'id'          => '_select[ + loop + ]', 
				'label'       => __( 'My Select Field', 'woocommerce' ), 
				'description' => __( 'Choose a value.', 'woocommerce' ),
				'value'       => '',
				'options' => array(
					'one'   => __( 'Option 1', 'woocommerce' ),
					'two'   => __( 'Option 2', 'woocommerce' ),
					'three' => __( 'Option 3', 'woocommerce' )
					)
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Checkbox
			woocommerce_wp_checkbox( 
			array( 
				'id'            => '_checkbox[ + loop + ]', 
				'label'         => __('My Checkbox Field', 'woocommerce' ), 
				'description'   => __( 'Check me!', 'woocommerce' ),
				'value'         => '', 
				)
			);
			?>
		</td>
	</tr>
	<tr>
		<td>
			<?php
			// Hidden field
			woocommerce_wp_hidden_input(
			array( 
				'id'    => '_hidden_field[ + loop + ]', 
				'value' => 'hidden_value'
				)
			);
			?>
		</td>
	</tr>
<?php
}

/**
 * Save new fields for variations
 *
*/
function save_variable_fields( $post_id ) {
	if (isset( $_POST['variable_sku'] ) ) :

		$variable_sku          = $_POST['variable_sku'];
		$variable_post_id      = $_POST['variable_post_id'];
		
		// Text Field
		$_text_field = $_POST['_text_field'];
		for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
			$variation_id = (int) $variable_post_id[$i];
			if ( isset( $_text_field[$i] ) ) {
				update_post_meta( $variation_id, '_text_field', stripslashes( $_text_field[$i] ) );
			}
		endfor;
		
		// Number Field
		$_number_field = $_POST['_number_field'];
		for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
			$variation_id = (int) $variable_post_id[$i];
			if ( isset( $_text_field[$i] ) ) {
				update_post_meta( $variation_id, '_number_field', stripslashes( $_number_field[$i] ) );
			}
		endfor;
		
		// Textarea
		$_textarea = $_POST['_textarea'];
		for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
			$variation_id = (int) $variable_post_id[$i];
			if ( isset( $_textarea[$i] ) ) {
				update_post_meta( $variation_id, '_textarea', stripslashes( $_textarea[$i] ) );
			}
		endfor;
		
		// Select
		$_select = $_POST['_select'];
		for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
			$variation_id = (int) $variable_post_id[$i];
			if ( isset( $_select[$i] ) ) {
				update_post_meta( $variation_id, '_select', stripslashes( $_select[$i] ) );
			}
		endfor;
		
		// Checkbox
		$_checkbox = $_POST['_checkbox'];
		for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
			$variation_id = (int) $variable_post_id[$i];
			if ( isset( $_checkbox[$i] ) ) {
				update_post_meta( $variation_id, '_checkbox', stripslashes( $_checkbox[$i] ) );
			}
		endfor;
		
		// Hidden field
		$_hidden_field = $_POST['_hidden_field'];
		for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
			$variation_id = (int) $variable_post_id[$i];
			if ( isset( $_hidden_field[$i] ) ) {
				update_post_meta( $variation_id, '_hidden_field', stripslashes( $_hidden_field[$i] ) );
			}
		endfor;
		
	endif;
}

Hi, thanks for this code.
I get an error message:
Parse error: syntax error, unexpected ']'

Could you review this code?

Hi,
thank you !
Do you know how to display variation value in the frontend?
I mean I'd like to show/hide the custom field data per the respective product variation selected by the user (like SKU or price).

hi,
plz help! how i can to display it on front end?

Hello, Remi

Could you usnswer us please! As roltex I have the same question to you: How can I show this field on the product page, for ex. put EAN field near SKU field. As I understand I need to open my theme woocommerce folder/single-product/meta.php and put here a code, something like sku code
I just starting to meet wordpress backend, could you please help me with this?
Thank you for your attention to this matter
Best regards, Sergey

Hello there,

just noticed there are brackets ] in the lines 27, 43, 63, 78, 98, in the second parameter of the function get_post_meta correspondingly, making the code break. Found them all by searching '],

Thanks for sharing!

Bests,
Richard

WooCommerce 3 just came out. The function responsible for saving the data should be changed to something like this:

function save_custom_wc_fields( $variation_id, $i) {
	if (isset( $_POST["variable_sku"] ) ) {		
		$_text_field = isset($_POST["_my-super-duper-field"]) ? $_POST["_my-super-duper-field"] : false;
        if ($_text_field) {
            update_post_meta( $variation_id, "_rehvi-moot", stripslashes( $_text_field[$i] ) );
        }
    }
}

@roltex @whoaloic
I use

get_post_meta($variation_id, '_class_duration', true);

to display it in the frontend, where _class_duration is the name of my variable. As I saved just a number I want it to be returned not as an array but the value which is why I use the true.
See https://developer.wordpress.org/reference/functions/get_post_meta/ for further details.

Full code looks like this:

$all_orders = get_posts( array(
'numberposts' => -1,
'meta_key' => '_customer_user',
'meta_value' => get_current_user_id(),
'post_type' => wc_get_order_types(),
'post_status' => array_keys( wc_get_order_statuses() ),
) );

foreach($all_orders as $order){
$order_id = $order->ID;
$order = wc_get_order($order_id);

foreach ($order->get_items() as $item_id => $item_obj) {
	$variation_id = $item_obj->get_variation_id();
	$months = get_post_meta($variation_id, _class_duration, true);
	echo $months;
}

}

(Sorry, seems like the code is not correctly recognised as one by syntax highlighting. Not sure why)

Hope it helps anyway.
Best
Felix