在自定义 FungibleState 模式的瞬态父属性上对子类进行分组

Question

在 Corda V3 中，我们正在扩展 FungibleState，如 API Vault Query 文档中所述：

object CustomSchemaV1 : MappedSchema(schemaFamily = CustomSchema.javaClass, version = 1, mappedTypes = listOf(PersistentCustomState::class.java))
{
@Entity
@Table(name = "custom_states", indexes = arrayOf(Index(name = "custom_field_idx", columnList = "custom_field")))
class PersistentCustomState(

/** Custom attributes */
@Column(name = "custom_field")
var customField: String? = null,

/** FungibleState parent attributes */
@Transient
val _participants: Set<AbstractParty>,
@Transient
val _owner: AbstractParty,
@Transient
val _quantity: Long,
@Transient
val _issuerParty: AbstractParty,
@Transient
val _issuerRef: OpaqueBytes
) : CommonSchemaV1.FungibleState(_participants?.toMutableSet(), _owner, _quantity, _issuerParty, _issuerRef.bytes)}

使用这种模式，我们如何对 _quantity 父字段进行求和，按 custom_field 分组？

查看示例，我们尝试使用QueryCriteria：

val sum = builder {
    CustomSchemaV1.PersistentCustomState::_quantity.sum(
        groupByColumns = listOf(
            CustomSchemaV1.PersistentCustomState::customField
        ),
        orderBy = Sort.Direction.ASC
    )
}
return QueryCriteria.VaultCustomQueryCriteria(sum)

但这会引发错误：Unable to locate Attribute with the the given name [_quantity] on this ManagedType [net.corda.core.schemas.PersistentState]

我们能够解决删除 @Transient 注释的方法，该注释也将 quantity 保留在子类上，但这会导致在数据库中存储重复值。

Answer 1

您是否考虑过尝试以下方法：

object CustomSchemaV1 : MappedSchema(schemaFamily = CustomSchema.javaClass, version = 1, mappedTypes = listOf(PersistentCustomState::class.java))
{
@Entity
@Table(name = "custom_states", indexes = arrayOf(Index(name = "custom_field_idx", columnList = "custom_field")))
class PersistentCustomState(

/** Custom attributes */
@Column(name = "custom_field")
var customField: String? = null,

/** FungibleState parent attributes */
participants: MutableSet<AbstractParty>?,
owner: AbstractParty,
quantity: Long,
issuerParty: AbstractParty,
issuerRef: OpaqueBytes
) : CommonSchemaV1.FungibleState(participants, owner, quantity, issuerParty, issuerRef.bytes)}

然后使用继承的quantity 列？ CommonSchemaV1.FungibleState 是一个MappedSuperclass，所以它的列会被映射到子实体中。

Answer 2

这是一个正在此处跟踪的错误：https://r3-cev.atlassian.net/browse/CORDA-1338。