SimpleSyncProvider.DeleteItem 方法

在派生类中重写时，由 Sync Framework 运行时调用以便从目标存储区中删除某一项。

命名空间: Microsoft.Synchronization.SimpleProviders
程序集: Microsoft.Synchronization.SimpleProviders（在 microsoft.synchronization.simpleproviders.dll 中）

语法

声明
Public MustOverride Sub DeleteItem ( _
    keyAndExpectedVersion As ItemFieldDictionary, _
    recoverableErrorReportingContext As RecoverableErrorReportingContext, _
    <OutAttribute> ByRef commitKnowledgeAfterThisItem As Boolean _
)
用法
Dim instance As SimpleSyncProvider
Dim keyAndExpectedVersion As ItemFieldDictionary
Dim recoverableErrorReportingContext As RecoverableErrorReportingContext
Dim commitKnowledgeAfterThisItem As Boolean

instance.DeleteItem(keyAndExpectedVersion, recoverableErrorReportingContext, commitKnowledgeAfterThisItem)

public abstract void DeleteItem (
    ItemFieldDictionary keyAndExpectedVersion,
    RecoverableErrorReportingContext recoverableErrorReportingContext,
    out bool commitKnowledgeAfterThisItem
)

public:
virtual void DeleteItem (
    ItemFieldDictionary^ keyAndExpectedVersion, 
    RecoverableErrorReportingContext^ recoverableErrorReportingContext, 
    [OutAttribute] bool% commitKnowledgeAfterThisItem
) abstract

public abstract void DeleteItem (
    ItemFieldDictionary keyAndExpectedVersion, 
    RecoverableErrorReportingContext recoverableErrorReportingContext, 
    /** @attribute OutAttribute() */ /** @ref */ boolean commitKnowledgeAfterThisItem
)

JScript does not support passing value-type arguments by reference.

参数

• keyAndExpectedVersion
  要删除的项的键和预期版本属性。提供程序必须执行开放式并发检查，以便确认目标上的项的版本是否与 keyAndExpectedVersion 中找到的值相对应。如果此检查失败，提供程序应通过使用 RecoverableErrorReportingContext 对象报告一个可恢复错误。

• recoverableErrorReportingContext
  一个 RecoverableErrorReportingContext 对象，该对象用于报告在尝试删除某一项期间发生的可恢复错误。

• commitKnowledgeAfterThisItem
  返回在完成了对指定项的处理后 Sync Framework 运行时是否应将知识提交到元数据存储区。

备注

在 Sync Framework 检测到并加载了来自源的变更后，它必须将这些变更和相应的元数据变更应用于目标副本。位于目标的元数据变更由 Sync Framework 处理，但应用数据变更是特定于存储区的，应通过实现以下方法来处理：DeleteItem、InsertItem 和 UpdateItem。

示例

下面的代码示例演示此方法的实现，该方法将删除应用于内存中的示例数据存储区。若要在完整应用程序的上下文中查看此代码，请参见"Sync101 using Simple Sync Provider" 应用程序（可从 Sync Framework SDK 和 Code Gallery 获得）。

public override void DeleteItem(ItemFieldDictionary keyAndExpectedVersion, 
    RecoverableErrorReportingContext recoverableErrorReportingContext, 
    out bool commitKnowledgeAfterThisItem)
{
    IDictionary<uint, ItemField> expectedFields = (IDictionary<uint, ItemField>)keyAndExpectedVersion;
    ulong id = (ulong)expectedFields[CUSTOM_FIELD_ID].Value;
    if (_store.Contains(id))
    {
        _store.DeleteItem(id);
    }
    else
    {
        // If the item to delete does not exist, record an error on this change and 
        // continue with the rest of the session.
        recoverableErrorReportingContext.RecordRecoverableErrorForChange(new RecoverableErrorData(new Exception("Item not found in the store")));
    }
    commitKnowledgeAfterThisItem = false;
}

Public Overrides Sub DeleteItem(ByVal keyAndExpectedVersion As ItemFieldDictionary, ByVal recoverableErrorReportingContext As RecoverableErrorReportingContext, ByRef commitKnowledgeAfterThisItem As Boolean)
    Dim expectedFields As IDictionary(Of UInteger, ItemField) = DirectCast(keyAndExpectedVersion, IDictionary(Of UInteger, ItemField))
    Dim id As ULong = CULng(expectedFields(CUSTOM_FIELD_ID).Value)
    If _store.Contains(id) Then
        _store.DeleteItem(id)
    Else
        ' If the item to delete does not exist, record an error on this change and 
        ' continue with the rest of the session. 
        recoverableErrorReportingContext.RecordRecoverableErrorForChange(New RecoverableErrorData(New Exception("Item not found in the store")))
    End If
    commitKnowledgeAfterThisItem = False
End Sub

请参阅

参考

SimpleSyncProvider 类
SimpleSyncProvider 成员
Microsoft.Synchronization.SimpleProviders 命名空间