Question

这是我的架构生成代码：

    Schema schema = new Schema(VERSION, "com.example.dao");

    Entity player = schema.addEntity("Player");
    Property playerIdProperty = player.addStringProperty("id").primaryKey().getProperty();
    player.addStringProperty("name").notNull();
    player.addStringProperty("created_at");
    player.addStringProperty("updated_at");

    Entity match = schema.addEntity("Match");
    match.addStringProperty("id").primaryKey();
    match.addIntProperty("score1");
    match.addIntProperty("score2");
    match.addStringProperty("created_at");
    match.addStringProperty("updated_at");

    match.addToOne(player, playerIdProperty, "dp1");
    match.addToOne(player, playerIdProperty, "dp2");
    match.addToOne(player, playerIdProperty, "op1");
    match.addToOne(player, playerIdProperty, "op2");


    new DaoGenerator().generateAll(schema, "app/src-gen");

这就是它产生的结果：

public class MatchDao extends AbstractDao<Match, String> {

public static final String TABLENAME = "MATCH";

/**
 * Properties of entity Match.<br/>
 * Can be used for QueryBuilder and for referencing column names.
*/
public static class Properties {
    public final static Property Id = new Property(0, String.class, "id", true, "ID");
    public final static Property Score1 = new Property(1, Integer.class, "score1", false, "SCORE1");
    public final static Property Score2 = new Property(2, Integer.class, "score2", false, "SCORE2");
    public final static Property Created_at = new Property(3, String.class, "created_at", false, "CREATED_AT");
    public final static Property Updated_at = new Property(4, String.class, "updated_at", false, "UPDATED_AT");
    public final static Property Id = new Property(5, String.class, "id", true, "ID");
};

如您所见，在MatchDao中有两个名为“Id”的属性。我需要做的是生成两个表，主键是字符串（字符串是远程数据库的要求）和4个外键（每个匹配有4个播放器）。

问题是：为什么“Id”属性是重复的以及如何避免它？提前致谢

Answer 1

我犯了和你一样的错误。目前您正在执行以下操作：

Entity player = schema.addEntity("Player");
Property playerIdProperty = player.addStringProperty("id").primaryKey().getProperty();
...
match.addToOne(player, playerIdProperty, "dp1");

但是你必须将playerId属性添加到目标类：

Entity player = schema.addEntity("Player");
player.addStringProperty("id").primaryKey();
...
Entity match = schema.addEntity("Match");
Property player1IdProperty = match.addLongProperty("dp1").getProperty();
...
match.addToOne(player, player1IdProperty);

希望这有帮助！

Answer 2

我不确定但这个id属性不重复。此“id”属性是与实体“Player”的1：1关系产生的。也许addToOne(Entity target, Property fkProperty, java.lang.String name)方法存在一个错误。

Answer 3

也许addToOne函数需要一个整数属性？我建议你按照以下步骤操作：

更改主键。这也是外键：

Property playerIdProperty = player.addIdProperty().autoincrement().primaryKey().getProperty();`

创建唯一的字符串标识符：

player.addStringProperty("identifier").notNull().unique();

有了这个，你仍然有两个属性，但我认为模型更好。我赞成使用数字ID。抱歉我的英文。

Android GreenDAO会生成额外的ID属性

3 个答案: