Edit this page

Persist XmlaDataProvider

In this article we will show you how to persist the current state of XmlaDataProvider via Telerik's RadPersistenceFramework.

Persistence Framework

In this article we will show you how to serialize and deserialize XmlaDataProvider and all of its settings via RadPersistenceFramework. You can use this feature to save the current state of the provider and load it next time the application is started.

Persist XmlaDataProvider

We've added the DataContract attribute to all classes used by XmlaDataProvider. So you can easily serialize it by using DataContractSerializer.

So lets create a simple class that we'll use to save and load DataProviderSettings. You have to add the DataContract attribute to the new class and DataMember attribute for its properties.

[DataContract]
public class DataProviderSettings
{
    [DataMember]
    public object[] Aggregates { get; set; }

    [DataMember]
    public object[] Filters { get; set; }

    [DataMember]
    public object[] Rows { get; set; }

    [DataMember]
    public object[] Columns { get; set; }

    [DataMember]
    public int AggregatesLevel { get; set; }

    [DataMember]
    public PivotAxis AggregatesPosition { get; set; }
}
<DataContract> _
Public Class DataProviderSettings
    <DataMember> _
    Public Property Aggregates() As Object()

    <DataMember> _
    Public Property Filters() As Object()

    <DataMember> _
    Public Property Rows() As Object()

    <DataMember> _
    Public Property Columns() As Object()

    <DataMember> _
    Public Property AggregatesLevel() As Integer

    <DataMember> _
    Public Property AggregatesPosition() As PivotAxis
End Class

The next step is to create a new class, which implements Telerik.Windows.Persistence.Services.IValueProvider. IValueProvider has two methods that you will have to implement - ProvideValue and RestoreValue. The first one is used when the data is saved. The second one is used when the data is restored from a previously saved state. When saving the provider, you have to create an instance of DataProviderSettings class and set all of the properties. After that you can save the instance to a file or a stream. When using DataContractSerializer you have to give a collection of KnownTypes to the serializer. That's why we've created a new PivotSerializationHelper class which has a static member - KnownTypes. It consits of all types you'll need in order to serialize XmlaDataProvider. Here's an example how to implement it:

public abstract class DataProviderValueProvider : IValueProvider
{
    public abstract IEnumerable<Type> KnownTypes { get; }

    public string ProvideValue(object context)
    {
        string serialized = string.Empty;

        IDataProvider dataProvider = context as IDataProvider;
        if (dataProvider != null)
        {
            MemoryStream stream = new MemoryStream();

            DataProviderSettings settings = new DataProviderSettings()
            {
                Aggregates = dataProvider.Settings.AggregateDescriptions.OfType<object>().ToArray(),
                Filters = dataProvider.Settings.FilterDescriptions.OfType<object>().ToArray(),
                Rows = dataProvider.Settings.RowGroupDescriptions.OfType<object>().ToArray(),
                Columns = dataProvider.Settings.ColumnGroupDescriptions.OfType<object>().ToArray(),
                AggregatesLevel = dataProvider.Settings.AggregatesLevel,
                AggregatesPosition = dataProvider.Settings.AggregatesPosition
            };

            DataContractSerializer serializer = new DataContractSerializer(typeof(DataProviderSettings), KnownTypes);
            serializer.WriteObject(stream, settings);

            stream.Position = 0;
            var streamReader = new StreamReader(stream);
            serialized += streamReader.ReadToEnd();
        }

        return serialized;
    }

    public void RestoreValue(object context, string savedValue)
    {
        IDataProvider dataProvider = context as IDataProvider;
        if (dataProvider != null)
        {
            var stream = new MemoryStream();
            var tw = new StreamWriter(stream);
            tw.Write(savedValue);
            tw.Flush();
            stream.Position = 0;

            DataContractSerializer serializer = new DataContractSerializer(typeof(DataProviderSettings), KnownTypes);
            var result = serializer.ReadObject(stream);

            dataProvider.Settings.AggregateDescriptions.Clear();
            foreach (var aggregateDescription in (result as DataProviderSettings).Aggregates)
            {
                dataProvider.Settings.AggregateDescriptions.Add(aggregateDescription);
            }

            dataProvider.Settings.FilterDescriptions.Clear();
            foreach (var filterDescription in (result as DataProviderSettings).Filters)
            {
                dataProvider.Settings.FilterDescriptions.Add(filterDescription);
            }

            dataProvider.Settings.RowGroupDescriptions.Clear();
            foreach (var rowDescription in (result as DataProviderSettings).Rows)
            {
                dataProvider.Settings.RowGroupDescriptions.Add(rowDescription);
            }

            dataProvider.Settings.ColumnGroupDescriptions.Clear();
            foreach (var columnDescription in (result as DataProviderSettings).Columns)
            {
                dataProvider.Settings.ColumnGroupDescriptions.Add(columnDescription);
            }

            dataProvider.Settings.AggregatesPosition = (result as DataProviderSettings).AggregatesPosition;
            dataProvider.Settings.AggregatesLevel = (result as DataProviderSettings).AggregatesLevel;
        }
    }
}


public class XmlaValueProvider : DataProviderValueProvider
{
    public override IEnumerable<Type> KnownTypes
    {
        get
        {
            return XmlaPivotSerializationHelper.KnownTypes;
        }
    }
}
Public MustInherit Class DataProviderValueProvider
    Implements IValueProvider

    Public MustOverride ReadOnly Property KnownTypes() As IEnumerable(Of Type)

    Public Function ProvideValue(ByVal context As Object) As String
        Dim serialized As String = String.Empty

        Dim dataProvider As IDataProvider = TryCast(context, IDataProvider)
        If dataProvider IsNot Nothing Then
            Dim stream As New MemoryStream()

            Dim settings As New DataProviderSettings() With {.Aggregates = dataProvider.Settings.AggregateDescriptions.OfType(Of Object)().ToArray(), .Filters = dataProvider.Settings.FilterDescriptions.OfType(Of Object)().ToArray(), .Rows = dataProvider.Settings.RowGroupDescriptions.OfType(Of Object)().ToArray(), .Columns = dataProvider.Settings.ColumnGroupDescriptions.OfType(Of Object)().ToArray(), .AggregatesLevel = dataProvider.Settings.AggregatesLevel, .AggregatesPosition = dataProvider.Settings.AggregatesPosition}

            Dim serializer As New DataContractSerializer(GetType(DataProviderSettings), KnownTypes)
            serializer.WriteObject(stream, settings)

            stream.Position = 0
            Dim streamReader = New StreamReader(stream)
            serialized &= streamReader.ReadToEnd()
        End If

        Return serialized
    End Function

    Public Sub RestoreValue(ByVal context As Object, ByVal savedValue As String)
        Dim dataProvider As IDataProvider = TryCast(context, IDataProvider)
        If dataProvider IsNot Nothing Then
            Dim stream = New MemoryStream()
            Dim tw = New StreamWriter(stream)
            tw.Write(savedValue)
            tw.Flush()
            stream.Position = 0

            Dim serializer As New DataContractSerializer(GetType(DataProviderSettings), KnownTypes)
            Dim result = serializer.ReadObject(stream)

            dataProvider.Settings.AggregateDescriptions.Clear()
            For Each aggregateDescription In (TryCast(result, DataProviderSettings)).Aggregates
                dataProvider.Settings.AggregateDescriptions.Add(aggregateDescription)
            Next aggregateDescription

            dataProvider.Settings.FilterDescriptions.Clear()
            For Each filterDescription In (TryCast(result, DataProviderSettings)).Filters
                dataProvider.Settings.FilterDescriptions.Add(filterDescription)
            Next filterDescription

            dataProvider.Settings.RowGroupDescriptions.Clear()
            For Each rowDescription In (TryCast(result, DataProviderSettings)).Rows
                dataProvider.Settings.RowGroupDescriptions.Add(rowDescription)
            Next rowDescription

            dataProvider.Settings.ColumnGroupDescriptions.Clear()
            For Each columnDescription In (TryCast(result, DataProviderSettings)).Columns
                dataProvider.Settings.ColumnGroupDescriptions.Add(columnDescription)
            Next columnDescription

            dataProvider.Settings.AggregatesPosition = (TryCast(result, DataProviderSettings)).AggregatesPosition
            dataProvider.Settings.AggregatesLevel = (TryCast(result, DataProviderSettings)).AggregatesLevel
        End If
    End Sub
End Class   

Public Class XmlaValueProvider
    Inherits DataProviderValueProvider

    Public Overrides ReadOnly Property KnownTypes() As IEnumerable(Of Type)
        Get
            Return XmlaPivotSerializationHelper.KnownTypes
        End Get
    End Property
End Class

So the last step is to register a persistence provider and implement the logic to save and load the state of XmlaDataProvider:

Stream stream = new MemoryStream();

ServiceProvider.RegisterPersistenceProvider<IValueProvider>(typeof(XmlaDataProvider), new XmlaValueProvider());
//saving
PersistenceManager manager = new PersistenceManager();
this.stream = manager.Save(this.pivotGrid.DataProvider);

//loading 
this.stream.Position = 0;
PersistenceManager manager = new PersistenceManager();
manager.Load(this.pivotGrid.DataProvider, this.stream);
Dim stream As Stream = New MemoryStream()

ServiceProvider.RegisterPersistenceProvider(Of IValueProvider)(GetType(XmlaDataProvider), New XmlaValueProvider())
'saving'
Dim manager As New PersistenceManager()
Me.stream = manager.Save(Me.pivotGrid.DataProvider)

'loading'
Me.stream.Position = 0
Dim manager As New PersistenceManager()
manager.Load(Me.pivotGrid.DataProvider, Me.stream)

See Also