I have created a module with the following function in it, that does what I wanted. I had no issues so far except that I could not use the entity wrapper to save the nodes as it generated a "Maximum function nesting level of '100' reached" error.
Any critic welcome.
<?php
/**
* Implementation of hook_node_update()
* This will automatically add the variations to all other displays
* of the same content type.
*/
function variation_auto_node_update($node) {
// Make sure we don't get any cache issues
entity_get_controller('node')->resetCache(array($node->nid));
$langcode = field_language('node', $node, 'field_product_variations');
// Get Display variations
$variations = field_get_items('node', $node, 'field_product_variations');
if ($variations) {
// Build request to get all displays form variations
$query = db_select('field_data_field_product_variations', 'variations');
$query->fields('variations', array('entity_id'));
// Filter with OR by variation product Id
$db_or = db_or();
foreach ($variations as $pid) {
$db_or->condition('variations.field_product_variations_product_id', $pid);
}
// Filter by content type with AND
$db_and = db_and();
$db_and->condition('variations.bundle', $node->type, '=');
$db_and->condition($db_or);
$query->condition($db_and);
// Array of displays Ids
$nids = array_keys($query->execute()->fetchAllAssoc('entity_id'));
// Build request to get all variations from previous displays
$query = db_select('field_data_field_product_variations', 'variations');
$query->fields('variations', array('field_product_variations_product_id'));
$condition = db_or();
foreach ($nids as $nid) {
$condition->condition('variations.entity_id', $nid);
}
$query->condition($condition);
// Array of variations product Ids
$pids = array_keys($query->execute()->fetchAllAssoc('field_product_variations_product_id'));
// Now that we have all displays and products
$displays = node_load_multiple($nids);
foreach($displays as $display) {
// Update actual node
if ($display->nid == $node->nid) {
$display = $node;
}
// Get display actual variations product IDs
$local_pids = array_map(
function($item){return array_shift($item);},
field_get_items('node', $display, 'field_product_variations')
);
// Find missing variations and add them
if ($diff = array_diff($pids, $local_pids)) {
foreach ($diff as $pid) {
$display->field_product_variations[$langcode][]['product_id'] = (string)$pid;
}
node_save($display);
}
}
}
}
?>
