codytooker · January 18, 2018 21:27 · Jan 18, 2018
diff --git a/acf-sync-user-and-cpt-bidirectional-relationship.php b/acf-sync-user-and-cpt-bidirectional-relationship.php
@@ -0,0 +1,185 @@
+<?php
+
+/*
+ * This code is modified from the original here 
+ * https://github.com/Hube2/acf-filters-and-functions/blob/master/acf-reciprocal-relationship.php
+ *
+ * Some comments may not be useful anymore since the modifications
+ */
+
+
+function dod_dale_sync_users_and_groups($value, $post_id, $field) {
+
+	// set the two fields that you want to create
+	// a two way relationship for
+	// these values can be the same field key
+	// if you are using a single relationship field
+	// on a single post type
+
+	// the field key of one side of the relationship - CPT
+	$key_a = 'field_5a04f302ce2ae';
+
+	// the field key of the other side of the relationship - USER
+	$key_b = 'field_5a61019589d9b';
+
+	//set the type so we handle the differences in users and cpts ids
+	$type = 'post';
+
+	// figure out wich side we're doing and set up variables
+	// if the keys are the same above then this won't matter
+	// $key_a represents the field for the current posts
+	// and $key_b represents the field on related posts
+	if ($key_a != $field['key']) {
+		// this is side b, swap the value
+		$temp = $key_a;
+		$key_a = $key_b;
+		$key_b = $temp;
+
+		$type = 'user';
+		//when the field is a user we need to remove user_ from post_id
+		$post_id = substr($post_id, strpos($post_id, '_') + 1);
+	}
+
+	// get both fields
+	// this gets them by using an acf function
+	// that can gets field objects based on field keys
+	// we may be getting the same field, but we don't care
+	$field_a = acf_get_field($key_a);
+	$field_b = acf_get_field($key_b);
+
+	// set the field names to check
+	// for each post
+	$name_a = $field_a['name'];
+	$name_b = $field_b['name'];
+
+	// get the old value from the current post
+	// compare it to the new value to see
+	// if anything needs to be updated
+	// use get_post_meta() to a avoid conflicts
+	if ('user' == $type) {
+		$old_values = get_user_meta($post_id, $name_a, true);
+	} else {
+		$old_values = get_post_meta($post_id, $name_a, true);
+	}
+
+	// make sure that the value is an array
+	if (!is_array($old_values)) {
+		if (empty($old_values)) {
+			$old_values = array();
+		} else {
+			$old_values = array($old_values);
+		}
+	}
+	// set new values to $value
+	// we don't want to mess with $value
+	$new_values = $value;
+	// make sure that the value is an array
+	if (!is_array($new_values)) {
+		if (empty($new_values)) {
+			$new_values = array();
+		} else {
+			$new_values = array($new_values);
+		}
+	}
+
+	// get differences
+	// array_diff returns an array of values from the first
+	// array that are not in the second array
+	// this gives us lists that need to be added
+	// or removed depending on which order we give
+	// the arrays in
+
+	// this line is commented out, this line should be used when setting
+	// up this filter on a new site. getting values and updating values
+	// on every relationship will cause a performance issue you should
+	// only use the second line "$add = $new_values" when adding this
+	// filter to an existing site and then you should switch to the
+	// first line as soon as you get everything updated
+	// in either case if you have too many existing relationships
+	// checking end updated every one of them will more then likely
+	// cause your updates to time out.
+	//$add = array_diff($new_values, $old_values);
+	$add = $new_values;
+	$delete = array_diff($old_values, $new_values);
+
+	// reorder the arrays to prevent possible invalid index errors
+	$add = array_values($add);
+	$delete = array_values($delete);
+
+	if (!count($add) && !count($delete)) {
+		// there are no changes
+		// so there's nothing to do
+		return $value;
+	}
+
+	// do deletes first
+	// loop through all of the posts that need to have
+	// the recipricol relationship removed
+	for ($i=0; $i<count($delete); $i++) {
+		if ('post' == $type) {
+			$related_values = get_user_meta($delete[$i], $name_b, true);
+		} else {
+			$related_values = get_post_meta($delete[$i], $name_b, true);
+		}
+		if (!is_array($related_values)) {
+			if (empty($related_values)) {
+				$related_values = array();
+			} else {
+				$related_values = array($related_values);
+			}
+		}
+		// we use array_diff again
+		// this will remove the value without needing to loop
+		// through the array and find it
+		$related_values = array_diff($related_values, array($post_id));
+
+		if ('post' == $type) {
+			// insert the new value
+			update_user_meta($delete[$i], $name_b, $related_values);
+			// insert the acf key reference, just in case
+			update_user_meta($delete[$i], '_'.$name_b, $key_b);
+		} else {
+			// insert the new value
+			update_post_meta($delete[$i], $name_b, $related_values);
+			// insert the acf key reference, just in case
+			update_post_meta($delete[$i], '_'.$name_b, $key_b);
+		}
+	}
+
+	// do additions, to add $post_id
+	for ($i=0; $i<count($add); $i++) {
+		if ('post' == $type) {
+			$related_values = get_user_meta($add[$i], $name_b, true);
+		} else {
+			$related_values = get_post_meta($add[$i], $name_b, true);
+		}
+		if (!is_array($related_values)) {
+			if (empty($related_values)) {
+				$related_values = array();
+			} else {
+				$related_values = array($related_values);
+			}
+		}
+		if (!in_array($post_id, $related_values)) {
+			// add new relationship if it does not exist
+			$related_values[] = $post_id;
+		}
+
+		if ('post' == $type) {
+			// insert the new value
+			update_user_meta($add[$i], $name_b, $related_values);
+			// insert the acf key reference, just in case
+			update_user_meta($add[$i], '_'.$name_b, $key_b);
+		} else {
+			// insert the new value
+			update_post_meta($add[$i], $name_b, $related_values);
+			// insert the acf key reference, just in case
+			update_post_meta($add[$i], '_'.$name_b, $key_b);
+		}
+	}
+
+	return $value;
+
+}
+add_filter('acf/update_value/key=field_5a04f302ce2ae', 'dod_dale_sync_users_and_groups', 10, 3);
+add_filter('acf/update_value/key=field_5a61019589d9b', 'dod_dale_sync_users_and_groups', 10, 3);