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用一个data class来接收多表查的结果

Epc.kt 表1

@Entity(
    tableName = "epc",
    indices = [Index(value = ["epcId"], unique = true)]
)
data class Epc(
    /**
     * ID
     */
    @PrimaryKey(autoGenerate = true)
    val _id: Int = 0,
    /**
     * 企业编码
     */
    @ColumnInfo(name = "companyId")
    var companyId: String = "",
    /**
     * EPC 唯一编码
     */
    @ColumnInfo(name = "epcId")
    var epcId: String = "",
    /**
     * EPC 唯一编码
     */
    @ColumnInfo(name = "goodsId")
    var goodsId: Int = 0,
    /**
     * EPC 唯一编码
     */
    @ColumnInfo(name = "epcCode")
    var epcCode: String = "",
    /**
     * epcUrl
     */
    @ColumnInfo(name = "epcUrl")
    var epcUrl: String = "",

) {
    @Ignore
    constructor():this(_id = 0, companyId="",epcId = "",  goodsId= 0)
}

Goods.kt 表2

@Entity(
    tableName = "goods",
    indices = [Index(value = ["goodsId"], unique = true)]
)
data class Goods(
    /**
     * ID
     */
    @PrimaryKey(autoGenerate = true)
    val _id: Int = 0,
    /**
     * 企业编码
     */
    @ColumnInfo(name = "companyId")
    var companyId: String = "",
    /**
     * 产品 唯一编码
     */
    @ColumnInfo(name = "goodsId")
    var goodsId: Int = 0,
    /**
     * 产品 描述
     */
    @ColumnInfo(name = "goodsDesc")
    var goodsDesc: String = "",
) {
    @Ignore
    constructor():this(_id = 0, companyId="", goodsId= 0, goodsDesc="")
}

EpcData 接收结果类

data class EpcData(
    /* @ColumnInfo(name = "goodsId")
     var goodsid: String = "",*/

    @Embedded
    var epc: Epc? = null, // : Goods;

    @Relation(parentColumn = "goodsId", entityColumn = "goodsId")
    var epcList: List<Goods>? = null
) : Serializable {
    @Ignore
    constructor() : this(epc = null, epcList = null)
}

DAO操作

//芯片表Db
@Dao
interface EpcDao {
    @SuppressWarnings(RoomWarnings.CURSOR_MISMATCH)
    @Transaction
    @Query("SELECT * FROM EPC INNER JOIN GOODS ON EPC.goodsId = goods.goodsId  where EPC.companyId=:companyId")
    fun getTableData(companyId: String): List<EpcData>?
}