Android Room 数据库迁移从表中删除所有嵌入列

Question

我试图从某个表中删除“@Embedded”对象

class MigrateFrom28To29 : AutoMigrationSpec

示例：

@Entity
data class A(
   @PrimaryKey var a: String,
   var b: String,
   @Embedded(prefix = "c_") var c: C
)

data class C (
    val a: String,
    val b: String,
    val c: String,
): Serializable

在我的迁移类中添加注释：

@DeleteColumn(tableName = "A", columnName = "c_a")
@DeleteColumn(tableName = "A", columnName = "c_b")
@DeleteColumn(tableName = "A", columnName = "c_c")
class MigrateFrom28To29 : AutoMigrationSpec

当 C 类很复杂并且有很多成员时，有什么简单的方法可以做到这一点（不将每个成员添加到DeleteColumn）？

Answer 1

不认为有办法做到这一点，但你可以使用

@DeleteColumn.Entries(
    DeleteColumn(tableName = "A", columnName = "c_a"),
    DeleteColumn(tableName = "A", columnName = "c_b"),
    DeleteColumn(tableName = "A", columnName = "c_c"),
)