Méthode ChangeBatchBase.AddChange

Ajoute une modification d'élément spécifiée au groupe qui est actuellement ouvert.

Espace de noms: Microsoft.Synchronization
Assembly: Microsoft.Synchronization (dans microsoft.synchronization.dll)

Syntaxe

'Déclaration
Public Sub AddChange ( _
    change As ItemChange _
)
'Utilisation
Dim instance As ChangeBatchBase
Dim change As ItemChange

instance.AddChange(change)

public void AddChange (
    ItemChange change
)

public:
void AddChange (
    ItemChange^ change
)

public void AddChange (
    ItemChange change
)

public function AddChange (
    change : ItemChange
)

Paramètres

• change
  Modification d'élément à ajouter au groupe qui est actuellement ouvert.

Exceptions

Type d'exception	Condition
ChangeBatchIsReadOnlyException	Le lot de modifications a déjà été envoyé à un applicateur de modifications ou à une session de synchronisation. Les modifications ne peuvent pas être ajoutées au lot après qu'il a été envoyé.

Notes

Avant de pouvoir ajouter des modifications d'élément à un objet ChangeBatchBase, un groupe doit être ouvert en appelant la méthode BeginOrderedGroup ou BeginUnorderedGroup de l'objet ChangeBatch. Sinon, cette méthode lève l'exception InvalidOperationException.

Exemple

L'exemple suivant implémente la méthode GetChangeBatch en ajoutant des éléments à un groupe ordonné dans un lot de modifications. Un élément est ajouté uniquement quand sa version de modification n'est pas contenue dans la connaissance de destination.

Public Overrides Function GetChangeBatch(ByVal batchSize As UInteger, ByVal destinationKnowledge As SyncKnowledge) As ChangeBatch
    ' The destination knowledge must be converted to be compatible with the source replica
    ' before it can be used.
    Dim mappedDestKnowledge As SyncKnowledge = _knowledge.MapRemoteKnowledgeToLocal(destinationKnowledge)

    ' Create a new change batch, initialized by using the current knowledge of the source replica
    ' and a new ForgottenKnowledge object.
    Dim changeBatch As New ChangeBatch(IdFormats, GetKnowledge(), New ForgottenKnowledge())

    ' Start a group of changes in the change batch. The group is ordered by item ID.
    ' _getChangeBatchCurrent is 0 the first time GetChangeBatch is called, and is used to track the
    ' position in the metadata store for subsequent calls to GetChangeBatch.
    changeBatch.BeginOrderedGroup(_items.Values(_getChangeBatchCurrent).GlobalId)

    ' itemsAdded is incremented each time a change is added to the change batch. When itemsAdded
    ' is greater than the requested batch size, enumeration stops and the change batch is returned.
    Dim itemsAdded As Integer = 0

    Dim itemMeta As ItemMetadata

    ' Enumerate items and add a change to the change batch if it is not contained in the 
    ' destination knowledge.
    ' _items is a SortedList that contains ItemMetadata objects that are ordered by item ID.
    While itemsAdded <= batchSize AndAlso _getChangeBatchCurrent < _items.Count
        itemMeta = _items.Values(_getChangeBatchCurrent)
        Dim kind As ChangeKind = If((itemMeta.IsDeleted), ChangeKind.Deleted, ChangeKind.Update)
        Dim change As New ItemChange(IdFormats, ReplicaId, itemMeta.GlobalId, kind, itemMeta.CreationVersion, itemMeta.ChangeVersion)

        ' If the change is not contained in the destination knowledge, add it to the change batch.
        If Not mappedDestKnowledge.Contains(change) Then
            changeBatch.AddChange(change)
            itemsAdded += 1
        End If
        _getChangeBatchCurrent += 1
    End While

    ' End the group of changes in the change batch. Pass the current source knowledge.
    changeBatch.EndOrderedGroup(_items.Values(_getChangeBatchCurrent - 1).GlobalId, _knowledge)

    ' When all items in the metadata store have been enumerated, set this batch as the
    ' last batch.
    If _getChangeBatchCurrent = _items.Count Then
        changeBatch.SetLastBatch()
    End If

    Return changeBatch
End Function

public override ChangeBatch GetChangeBatch(uint batchSize, SyncKnowledge destinationKnowledge)
{
    // The destination knowledge must be converted to be compatible with the source replica
    // before it can be used.
    SyncKnowledge mappedDestKnowledge = _knowledge.MapRemoteKnowledgeToLocal(destinationKnowledge);

    // Create a new change batch, initialized by using the current knowledge of the source replica
    // and a new ForgottenKnowledge object.
    ChangeBatch changeBatch = new ChangeBatch(IdFormats, GetKnowledge(), new ForgottenKnowledge());

    // Start a group of changes in the change batch. The group is ordered by item ID.
    // _getChangeBatchCurrent is 0 the first time GetChangeBatch is called, and is used to track the
    // position in the metadata store for subsequent calls to GetChangeBatch.
    changeBatch.BeginOrderedGroup(_items.Values[_getChangeBatchCurrent].GlobalId);
    
    // itemsAdded is incremented each time a change is added to the change batch. When itemsAdded
    // is greater than the requested batch size, enumeration stops and the change batch is returned.
    int itemsAdded = 0;
    
    ItemMetadata itemMeta;

    // Enumerate items and add a change to the change batch if it is not contained in the 
    // destination knowledge.
    // _items is a SortedList that contains ItemMetadata objects that are ordered by item ID.
    for (; itemsAdded <= batchSize && _getChangeBatchCurrent < _items.Count; _getChangeBatchCurrent++)
    {
        itemMeta = _items.Values[_getChangeBatchCurrent];
        ChangeKind kind = (itemMeta.IsDeleted) ? ChangeKind.Deleted : ChangeKind.Update;
        ItemChange change = new ItemChange(IdFormats, ReplicaId, itemMeta.GlobalId, kind, itemMeta.CreationVersion, 
            itemMeta.ChangeVersion);

        // If the change is not contained in the destination knowledge, add it to the change batch.
        if (!mappedDestKnowledge.Contains(change))
        {
            changeBatch.AddChange(change);
            itemsAdded++;
        }
    }

    // End the group of changes in the change batch. Pass the current source knowledge.
    changeBatch.EndOrderedGroup(_items.Values[_getChangeBatchCurrent - 1].GlobalId, _knowledge);

    // When all items in the metadata store have been enumerated, set this batch as the
    // last batch.
    if (_getChangeBatchCurrent == _items.Count)
    {
        changeBatch.SetLastBatch();
    }

    return changeBatch;
}

Voir aussi

Référence

Classe ChangeBatchBase
Membres ChangeBatchBase
Espace de noms Microsoft.Synchronization