Convert Attribute to Uppercase

convert-attribute-to-uppercase.php

<?php

/**
 * Alter Product feed item
 * Uppercase a source value (attribute_pa_cup) and combine with an other source value in the size attribute
 */
function alter_feed_item( $attributes, $feed_id, $product_id ) {
	
  	// get values
  	$attribute_pa_band  = $attributes['custom_label_0']; //add the attribute_pa_band to attribute "custom_label_0"
  	$attribute_pa_cup   = $attributes['custom_label_1']; //add the attribute_pa_cup to attribute "custom_label_1"
  
  	// uppercase attribute_pa_cup
  	$attribute_pa_cup = strtoupper($attribute_pa_cup); //make upper case
  
  	//combine and add to the size attribute BUT only if custom_label_0 and custom_label_1 contain values.
	if( !empty($attributes['custom_label_0'] ) && !empty($attributes['custom_label_1'] ) ){
  		$attributes['size'] = $attribute_pa_band . " " . $attribute_pa_cup; 
	}

	// IMPORTANT! Always return the $attributes
	return $attributes;
}
add_filter( 'wppfm_feed_item_value', 'alter_feed_item', 10, 3 );