Persist XmlaDataProvider
The implementation demonstrated in this article can also be reviewed in the Persist XmlaDataProvider SDK Example of the SDK Examples Browser
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)