房间不知道如何将此字段保存到数据库中

Question

我需要你的帮助。我试图在没有反序列化的情况下找到解决方案，但我什么也没找到。如果你能帮我就好了...所以我有了下面的JSON文件

"resources": [{
    "id": 441988,
    "name": "TVA",
    "parent": {
      "id": 159
    },
  },
  {
    "id": 441900,
    "name": "Marketing",
    "parent": {
      "id": 166
    },
}]

    @Entity(tableName = "resources")
    class CategoryBean {

    @PrimaryKey
    @ColumnInfo(name = "resource_id")
    @SerializedName("id")
    private var mId: Int = 0

    @ColumnInfo(name = "name")
    @SerializedName("name")
    private var mName: String? = null

    @ColumnInfo(name = "parent")
    @SerializedName("parent")
    private var mParent: ParentBean? = null

    fun getId(): Int {
        return mId
    }

    fun getName(): String? {
        return mName
    }

    fun getParent(): ParentBean? {
        return mParent
    }

    fun setParent(parent: ParentBean) {
        mParent = parent
    }

    fun setId(id: Int) {
        mId = id
    }

    fun setName(name: String) {
        mName = name
    }

class ParentBean {

    @SerializedName("id")
    private var mId: Int = 0

    fun getId(): Int? {
        return mId
    }

}

谢谢你的时间和帮助。

我有以下错误：

Cannot figure out how to save this field into database. You can consider adding a type converter for it.

Answer 1

Room工作在SQLite数据库之上，当您将类注释为@Entity时，您正在创建一个表，该表的列是根据类的属性定义的，因此您不能直接存储像ParentBean这样的自定义类型，为此，您需要将Mparent属性注释为@Embedded:

@Entity(tableName = "resources")
class CategoryBean constructor(
    @PrimaryKey
    @ColumnInfo(name = "resource_id")
    @SerializedName("id")
    var mId: Int,
    @ColumnInfo(name = "name")
    @SerializedName("name")
    var mName: String?,
    @SerializedName("parent")
    @Embedded
    var mParent: ParentBean?
)

然后在ParentBean中为属性定义列名：

data class ParentBean constructor(@SerializedName("id") @ColumnInfo(name = "parent_id")var mId: Int)

资源表将具有以下列:resource_id、name、parent_id

来源：https://developer.android.com/training/data-storage/room/defining-data

注意：您不需要在Kotlin中手动定义getter和setter。