PersistenceParticipant.CollectValues Method

Reference

Definition

Namespace:: System.Activities.Persistence

Assembly:: System.Activities.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

A host invokes this method on a custom persistence participant to collect read-write values and write-only values, to be persisted.

protected:
 virtual void CollectValues([Runtime::InteropServices::Out] System::Collections::Generic::IDictionary<System::Xml::Linq::XName ^, System::Object ^> ^ % readWriteValues, [Runtime::InteropServices::Out] System::Collections::Generic::IDictionary<System::Xml::Linq::XName ^, System::Object ^> ^ % writeOnlyValues);

protected virtual void CollectValues (out System.Collections.Generic.IDictionary<System.Xml.Linq.XName,object> readWriteValues, out System.Collections.Generic.IDictionary<System.Xml.Linq.XName,object> writeOnlyValues);

abstract member CollectValues : IDictionary * IDictionary -> unit
override this.CollectValues : IDictionary * IDictionary -> unit

Protected Overridable Sub CollectValues (ByRef readWriteValues As IDictionary(Of XName, Object), ByRef writeOnlyValues As IDictionary(Of XName, Object))

Parameters

readWriteValues: IDictionary<XName,Object>

The read-write values to be persisted.

writeOnlyValues: IDictionary<XName,Object>

The write-only values to be persisted.

Examples

The following code sample demonstrates using CollectValues in a class that derives from PersistenceParticipant. This example is from the Persistence Participants sample.

public class StepCountExtension : PersistenceParticipant
{
    static XNamespace stepCountNamespace = XNamespace.Get("urn:schemas-microsoft-com:Microsoft.Samples.WF/WorkflowInstances/properties");
    static XName currentCountName = stepCountNamespace.GetName("CurrentCount");

    int currentCount;

    public int CurrentCount
    {
        get
        {
            return this.currentCount;
        }
    }

    internal void IncrementStepCount()
    {
        this.currentCount += 1;
    }

    protected override void CollectValues(out IDictionary<XName, object> readWriteValues, out IDictionary<XName, object> writeOnlyValues)
    {
        readWriteValues = new Dictionary<XName, object>(1) { { currentCountName, this.currentCount } };
        writeOnlyValues = null;
    }

    protected override void PublishValues(IDictionary<XName, object> readWriteValues)
    {
        object loadedData;
        if (readWriteValues.TryGetValue(currentCountName, out loadedData))
        {
            this.currentCount = (int)loadedData;
        }
    }
}

Remarks

The host packages read-write values in the first dictionary as InstanceValue objects of an InstanceData collection, and packages write-only values in the second dictionary as InstanceValue objects with Optional and WriteOnly flags set. For more information, see InstanceValueOptions.