FOS\UserBundle\Document\UserManager::getQueryArray PHP Method

    protected function getQueryArray($classMetadata, $value, $fieldName)
    {
        $field = $this->getFieldNameFromPropertyPath($fieldName);
        if (!isset($classMetadata->fieldMappings[$field])) {
            throw new \LogicException("Mapping for '{$fieldName}' doesn't exist for " . $this->class);
        }
        $mapping = $classMetadata->fieldMappings[$field];
        if (isset($mapping['reference']) && $mapping['reference']) {
            throw new \LogicException('Cannot determine uniqueness of referenced document values');
        }
        $criteria[$field] = $value instanceof UserInterface ? $classMetadata->getFieldValue($value, $field) : $value;
        return $criteria;
    }