src/Collection.php
public function search($field, $value, $strict = false)
    {
        $value = is_array($value) ? $value : array($value);
        foreach ($this as $key => $entity) {
            if (isset($entity->$field) && in_array($entity->$field, $value, $strict)) {
                return $key;
            }
        }

        return false;
    }
public function search($field, $value, $strict = false)
    {
        $value = is_array($value) ? $value : array($value);
        foreach ($this as $key => $entity) {
            if (isset($entity->$field) && in_array($entity->$field, $value, $strict)) {
                return $key;
            }
        }

        return false;
    }
Search for an element with given property and value

@param string $field name of property
@param mixed $value value to compare
@param bool $strict compare value and type of property

@return integer|string|false