ExtensionQueryField.java 文件源码

@SuppressWarnings("unchecked")
protected SetJoin<UserEntity, ExtensionFieldValueEntity> createOrGetJoin(String alias, Root<UserEntity> root,
                                                                         SetAttribute<UserEntity, ExtensionFieldValueEntity> attribute) {

    for (Join<UserEntity, ?> currentJoin : root.getJoins()) {
        if (currentJoin.getAlias() == null) {
            // if alias is null, it is not an alias for an extension join, so we ignore it
            continue;
        }

        if (currentJoin.getAlias().equals(alias)) {
            return (SetJoin<UserEntity, ExtensionFieldValueEntity>) currentJoin;
        }
    }

    final SetJoin<UserEntity, ExtensionFieldValueEntity> join = root.join(attribute, JoinType.LEFT);

    join.alias(alias);

    return join;
}