Turn relation_get_related_entity into relation_get_related_entities

Hrm. I can see the use of such a function, but I don't think we can replace relation_get_related_entity() with it, because that would unnecessarily and massively increase the processing required on entities with many relations on them (think using relations as a replacement for taxonomy).

Then again, I don't really know why we have relation_get_related_entity() at all. It's only used in tests. We could probably replace it with something like your function, but that would require the ability to limit the number of relations searched for in the relation query, with EFQ::range().

Er, no. The query shouldn't return relations. It should return entities that are in relations with the given entity... We have relation_query for that, or at least, it wouldn't be hard to write a wrapper for it to load the relations.

Like said, I don't know what use the current function is, and before we introduce the new one, perhaps it'd be good to get an actual use-case to see how it'd be designed.

And you're returning an array, keyed by relation id, of arrays consisting of all other endpoint entity objects? I was originally thinking it would make more sense to just return a flat array of all entity objects, but I'm not so sure now. Would mean you didn't have to do a double loop with the results, but I guess that's not a huge problem..

We'd definitely need to be able to limit it somehow though, whether by number of relations checked, or number of entities returned, I don't know (and would that count entities that appear in more than one relation?)

Key by "entity_type:entity_id" - entity types can have underscores in them.

This is beginning to sound more and more like an extension of relation_query...

I think it would probably make sense as a new class extending RelationQuery with a different execute() method, but there might be a way to do it just as an additional set of methods/variables in RelationQuery... not sure.

I also needed to get all relations from an entity. But I needed the full relation data as I have fields on the relations and I need to read the data.
I also wanted them grouped by relation types in an array.

This the code that works perfectly for me. As I ran into this post, though I would share my it.

function mymodule_relation_get($entity_type, $entity_id, $relation_type = NULL, $r_index = NULL) {
  $query = relation_query($entity_type, $entity_id, $r_index);
  if ($relation_type) {
    $query->entityCondition('bundle', $relation_type);
  }
  $results = $query->execute();
  $result = reset($results);
  if (empty($result)) {
    return FALSE;
  }
  // Loop through each relation
  foreach ($results as $relation) $rids[] = $relation->rid;
  // Load all related entities endpoint references
  $raw_relations = relation_load_multiple($rids);
  
  // Reformat relations output.
  foreach ($raw_relations as $relation) {
	if (!isset($relations[$relation->relation_type])) {
		$relations[$relation->relation_type] = array();
	}
	$relations[$relation->relation_type][] = $relation;
  }
  
  return $relations;
 }

#14 works nicely.

No it doesn't: it returns relations. The original post is about returning entities.

I'm still luke-warm about this function, but if it's going to get in, then it needs to be a method on relationQuery, if not an extension of relationQuery. And it needs safeguards so that it won't kill a site by trying to load millions of entities.

I was just running into this issue. After trying to implement relation_get_related_entities I saw, that I have to calculate twice. One time I have to create a huge array, and the other time I have to get the fragments again. So my approach was to use relation_query directly in my template. In the beginning I was not aware of how to use it, but after studying the helpful posts here, it was possible to do it. Even if this post is older than 3 years, maybe it's helpful for someone coming from seo (like me).

<?php
    // results from relation_query to get relation id
    $query = relation_query('user', $user->uid); // in my case I was searching for nodes related to specific user
    // filtering by "my_type", choose your relation type here or leave this line out
    $query->propertyCondition('relation_type', 'my_type');
    $results = $query->execute();
?>
<?php foreach($results as $result): ?>
    <?php
        // get relation object
        $relation = relation_load($result->rid);
        // get endpoints respectively entities of type "node" (related to specific user)
        $endpoints = relation_get_endpoints($relation, 'node');
        // first endpoint is just equal to node object
        $node = reset($endpoints['node']);
    ?>
    <?php print $node->title; // just print whatever you need ?>
<?php endforeach; ?>