Question

GreenDao提供addProtobufEntity方法让您直接保存protobuf对象。不幸的是，我找不到很多解释如何使用此功能的文档。

假设我正在尝试将外键添加到我的Message实体中，以便我可以访问其PBSender protobuf实体。这是我的生成器代码：

// Define the protobuf entity
Entity pbSender = schema.addProtobufEntity(PBSender.class.getSimpleName());
pbSender.addIdProperty().autoincrement();

// Set up a foreign key in the message entity to its pbSender
Property pbSenderFK = message.addLongProperty("pbSenderFK").getProperty();
message.addToOne(pbSender, pbSenderFK, "pbSender");

不幸的是，生成的代码无法编译，因为它试图在我的PBSender类上访问一个不存在的getId（）方法：

public void setPbSender(PBSender pbSender) {
    synchronized (this) {
        this.pbSender = pbSender;
        pbSenderID = pbSender == null ? null : pbSender.getId();
        pbSender__resolvedKey = pbSenderID;
    }
}

有人可以解释如何管理协议缓冲实体的关系吗？

GreenDao目前仅支持Long主键。我的protobuf对象是否需要一种方法来返回唯一的长ID以用作主键？

如果我删除了自动增量ID，则生成步骤将失败，并显示以下错误：

java.lang.RuntimeException: Currently only single FK columns are supported: ToOne 'pbSender' from Message to PBSender

Answer 1

greenDAO generator Entity source code表明它目前不支持与协议缓冲区实体的关系：

public ToMany addToMany(Property[] sourceProperties, Entity target, Property[] targetProperties) {
    if (protobuf) {
        throw new IllegalStateException("Protobuf entities do not support realtions, currently");
    }

    ToMany toMany = new ToMany(schema, this, sourceProperties, target, targetProperties);
    toManyRelations.add(toMany);
    target.incomingToManyRelations.add(toMany);
    return toMany;
}

/**
 * Adds a to-one relationship to the given target entity using the given given foreign key property (which belongs
 * to this entity).
 */
public ToOne addToOne(Entity target, Property fkProperty) {
    if (protobuf) {
        throw new IllegalStateException("Protobuf entities do not support realtions, currently");
    }

    Property[] fkProperties = {fkProperty};
    ToOne toOne = new ToOne(schema, this, target, fkProperties, true);
    toOneRelations.add(toOne);
    return toOne;
}

但是，如果你的Protobuf类包含一个唯一的长ID和一个public Long getId()方法来返回该ID，我怀疑你可以做到这一点。

如何使用GreenDao直接保存协议缓冲区类

1 个答案: