Spot\Mapper::with PHP Method

    protected function with($collection, $entityName, $with = [])
    {
        $eventEmitter = $this->eventEmitter();
        $return = $eventEmitter->emit('beforeWith', [$this, $collection, $with]);
        if (false === $return) {
            return $collection;
        }
        foreach ($with as $relationName) {
            // We only need a single entity from the collection, because we're
            // going to modify the query to pass in an array of all the
            // identity keys from the collection instead of just that single entity
            $singleEntity = $collection->first();
            // Ensure we have a valid entity object
            if (!$singleEntity instanceof Entity) {
                throw new Exception("Relation object must be instance of 'Spot\\Entity', given '" . get_class($singleEntity) . "'");
            }
            $relationObject = $singleEntity->relation($relationName);
            // Ensure we have a valid relation name
            if ($relationObject === false) {
                throw new Exception("Invalid relation name eager-loaded in 'with' clause: No relation on {$entityName} with name '{$relationName}'");
            }
            // Ensure we have a valid relation object
            if (!$relationObject instanceof Relation\RelationAbstract) {
                throw new Exception("Relation object must be instance of 'Spot\\Relation\\RelationAbstract', given '" . get_class($relationObject) . "'");
            }
            // Hook so user can load custom relations their own way if they
            // want to, and then bypass the normal loading process by returning
            // false from their event
            $return = $eventEmitter->emit('loadWith', [$this, $collection, $relationName]);
            if (false === $return) {
                continue;
            }
            // Eager-load relation results back to collection
            $collection = $relationObject->eagerLoadOnCollection($relationName, $collection);
        }
        $eventEmitter->emit('afterWith', [$this, $collection, $with]);
        return $collection;
    }