Question

我面临一个非常烦人的错误。我正在实施会议室DB。当我在DAO中为另一个表编写插入查询时，类android studio会生成与android数据绑定相关的编译错误这是我的DAO课

@Dao
public interface MyCustomDAO {

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insertShop(ShopModel shop);

    //whenever i write this insert query, my android studio generate the stated error
   // and when i remove it project buil successfully

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insertAbout(AboutEntity about);

    @Query("Select * From shops")
    LiveData<List<ShopModel>> getShopsData();

}

这是我的关于实体类

@Entity(
    tableName = "about",
    foreignKeys = {@ForeignKey(entity = ShopModel.class,parentColumns = "shop_id",childColumns = "id")}
    )
// i have implemented the shopModel class with a col namely, shop_id
public class AboutEntity {

@NonNull
@ColumnInfo(name = "id")
private String shopId;
@ColumnInfo
private String monToFriTiming;
@ColumnInfo
private String satTiming;
@ColumnInfo
private String sunTiming;
@ColumnInfo
private String description;

public AboutEntity(@NonNull String shopId, String monToFriTiming, String satTiming, String sunTiming, String description) {
    this.shopId = shopId;
    this.monToFriTiming = monToFriTiming;
    this.satTiming = satTiming;
    this.sunTiming = sunTiming;
    this.description = description;
}

@NonNull
public String getShopId() {
    return shopId;
}
// other fields getter Methods

}

这是ShopModel类

@Entity
public class ShopModel {
@NonNull
@PrimaryKey
@ColumnInfo(name = "shop_id")
private String id;

 // some other fields and their implementation in the constructor and getter methods for them

public ShopModel(@NonNull String id) {
    this.id = id;
}

@NonNull
public String getId() {
    return id;
}

} build failed log

Answer 1

在看不到实际错误的情况下很难分辨，但是我的猜测是您的问题是由于在同一DAO中针对不同实体具有多种插入方法所致。

代替这样做：

@Dao
public interface WrongDAO {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insertShop(ShopModel shop);

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insertAbout(AboutEntity about);

    @Query("Select * From shops")
    LiveData<List<ShopModel>> getShopsData();
}

通常，您应该始终为每个实体创建一个不同的DAO ，以使代码更有条理：

@Dao
public interface ShopDAO {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insertShop(ShopModel shop);

    @Query("Select * From shops")
    LiveData<List<ShopModel>> getShopsData();
}

@Dao
public interface AboutDAO {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insertAbout(AboutEntity about);
}

我不确定在Room中是否必须执行此操作，但是到目前为止，我看到的所有示例每个实体都有一个DAO，所以我可能会坚持下去。

来自official documentation：

建议您的代码库中包含多个Dao类取决于他们接触的桌子。

要使其正常工作，请记住在Room数据库的声明中包括所有DAO！

在文件，数据绑定，Room DB中找到重复的类

1 个答案: