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本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# 載入已移除實體的欄位資料
<a name="working-with_app-sdk_ent_readwrite_load-removed"></a>

您無法載入 （從狀態結構讀取） 實體欄位資料，用於已從應用程式的擁有權和訂閱區域移除的實體。下列範例會導致 錯誤，因為它因為 而`Api::LoadIndexKey()`呼叫實體`Api::ChangeListAction::Remove`。第二個範例顯示直接在應用程式中存放和載入實體資料的正確方式。

**Example 不正確程式碼的範例**  

```
Result<void> ProcessSubscriptionChanges(Transaction& transaction)
{
    /* ... */
    
    WEAVERRUNTIME_TRY(Api::SubscriptionChangeList subscriptionChangeList, 
        Api::AllSubscriptionEvents(transaction));
    
    for (const Api::SubscriptionEvent& event : 
        subscriptionChangeList.changes)
    {
        switch (event.action)
        {
        case Api::ChangeListAction::Remove:
            {
                std::int8_t* dest = nullptr;
    
                /**
                 * Error!
                 * This calls LoadEntityIndexKey on an entity that
                 * has been removed from the subscription area.
                 */
                WEAVERRUNTIME_TRY(Api::LoadEntityIndexKey(
                    transaction,
                    event.entity,
                    Api::BuiltinTypeIdToTypeId(
                        Api::BuiltinTypeId::Vector3F32),
                    &dest));
    
                AZ::Vector3 position = 
                    *reinterpret_cast<AZ::Vector3*>(dest);
                break;
            }
        }
 
    }

    /* ... */
}
```

**Example 在應用程式中存放和載入實體資料的正確方式範例**  

```
Result<void> ReadAndSaveSubscribedEntityPositions(Transaction& transaction)
{
    static std::unordered_map<Api::EntityId, AZ::Vector3> 
        positionsBySubscribedEntity;

    WEAVERRUNTIME_TRY(Api::SubscriptionChangeList subscriptionChangeList, 
        Api::AllSubscriptionEvents(transaction));

    for (const Api::SubscriptionEvent& event : 
        subscriptionChangeList.changes)
    {
        switch (event.action)
        {
        case Api::ChangeListAction::Add:
            {
                std::int8_t* dest = nullptr;

                /**
                 * Add the position when the entity is added.
                 */
                WEAVERRUNTIME_TRY(Api::LoadEntityIndexKey(
                    transaction,
                    event.entity,
                    Api::BuiltinTypeIdToTypeId(
                        Api::BuiltinTypeId::Vector3F32),
                    &dest));

                AZ::Vector3 position = 
                    *reinterpret_cast<AZ::Vector3*>(dest);
                positionsBySubscribedEntity.emplace(
                    event.entity.descriptor->id, position);

                break;
            }
        case Api::ChangeListAction::Update:
            {
                std::int8_t* dest = nullptr;

                /**
                 * Update the position when the entity is updated.
                 */
                WEAVERRUNTIME_TRY(Api::LoadEntityIndexKey(
                    transaction,
                    event.entity,
                    Api::BuiltinTypeIdToTypeId(
                        Api::BuiltinTypeId::Vector3F32),
                    &dest));

                AZ::Vector3 position = 
                    *reinterpret_cast<AZ::Vector3*>(dest);
                positionsBySubscribedEntity[event.entity.descriptor->id] = 
                    position;

                break;
            }
        case Api::ChangeListAction::Remove:
            {
                /**
                 * Load the position when the entity is removed.
                 */
                AZ::Vector3 position = positionsBySubscribedEntity[
                    event.entity.descriptor->id];

                /**
                 * Do something with position...
                 */
                break;
            }
        }
    }
    
    /* ... */
}
```