Question

我与Realm合作已有一年多了，所以我对整个迁移流程并不陌生，但这让我ing了几天：

在将数据迁移到新的架构版本期间，我需要创建一些对象并将其插入数据库，然后再将它们连接到另一种对象。

首先，我创建了动态对象的映射，以便以后可以将它们连接到第二种类型：

    val generatedStoreVisitTypes = mutableMapOf<String, DynamicRealmObject>()

然后我创建并使用dynamicObjects

fun migrateToVersion19(realm: DynamicRealm) {

    // an extension method I created which adds the field if it doesn’t exist already, impl at the bottom
    realm.schema.getOrCreate<RealmMetadata>()
        // an extension method I created which adds the field if it doesn’t exist already, impl at the bottom
        .safeAddRealmListField(RealmMetadata::storeVisitTypes, realm.schema)
        .transform { metadata ->
            // I use the string name of the property here and not reflection since this field is deleted during this migration
            val currentStoreTaskList = metadata.getList("storeTasks")
            currentStoreTaskList.forEach { storeTasks ->
                // create an instance here and initialise it
                val visitTypeTasks = realm.createObject(MetaVisitTypeTasks::class.java.simpleName)
                visitTypeTasks[MetaVisitTypeTasks::visitTypeId.name] = "1"
                val visitTasks = visitTypeTasks.getList(MetaVisitTypeTasks::visitTasks.name)
                storeTasks.getList("storeTasks").forEach {
                    visitTasks.add(it)
                }

                // save the object to the map
                generatedStoreVisitTypes[storeUid] = visitTypeTasks
                }
            }
            .safeRemoveField("storeTasks")

        realm.schema.getOrCreate<RealmStore>()
        .safeAddRealmListField(RealmStore::visitTypes, realm.schema)
        .transform {
            val storeUid = it.getString(RealmStore::storeUid.name)
            // crash here on the “add” method
            it.getList(RealmStore::visitTypes.name).add(generatedStoreVisitTypes[storeUid])
        }
    }
}

private inline fun <reified T> RealmSchema.getOrCreate(): RealmObjectSchema {
    return get(T::class.java.simpleName) ?: create(T::class.java.simpleName)
}

private inline fun <reified TClass : RealmObject, reified TListItem : RealmObject, reified TList : RealmList<TListItem>> RealmObjectSchema.safeAddRealmListField(addedField: KMutableProperty1<TClass, TList>, schema: RealmSchema): RealmObjectSchema {
    val fieldName = addedField.name
    val listItemObjectSchema = schema.get(TListItem::class.java.simpleName)

    if (!hasField(fieldName)) {
        return addRealmListField(fieldName, listItemObjectSchema)
    }
    return this
}

在第二个“转换”方法中调用“添加”方法有时会导致-

“ java.lang.IllegalStateException：对象不再有效，无法对其进行操作。它被另一个线程删除了吗？”

我对此错误很熟悉，通常知道如何处理该错误，但是在这种情况下我无法重新创建或理解这种情况。既然我们在谈论迁移，那么不应有另一个线程在同一架构上运行-执行是同步的，不是吗？另外，我们所说的是刚刚创建的对象。没有其他引用或使用上下文。

我不知道如何删除该对象。是什么原因导致这种错误？

迁移期间Realm db DynamicRealmObject无效

0 个答案: