Serialization

The implementation demonstrated in this article can also be reviewed in the Serialize QueryableDataProvider SDK Example of the SDK Examples Browser

This article will go through the process of serializing and deserializing the current state of QueryableDataProvider. Through it the state of the control can be persisted and loaded the next time the application is started.

Using the DataContract Attribute

The DataContract attribute is added to all classes used by the QueryableDataProvider. This enables easy serialization with the DataContractSerializer. Below is a sample definition of such classes. The DataContract attribute is added on class level and the DataMember one is added for each property.

Example 1: Using the DataContract attribute

[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; } 
} 

Implementing the Serializer

The next step is to implement the serializer. When serializing the provider an instance of the DataProviderSettings class has to be created with all of its properties set. After that you can serialize the instance to a file or a stream.

Example 2: Implementing the Serializer

 public abstract class DataProviderSerializer 
{ 
    public abstract IEnumerable<Type> KnownTypes { get; } 
 
    public string Serialize(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 Deserialize(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; 
        } 
    } 
} 

Specifying the KnownTypes

In the previous example a collection of KnownTypes is passed to the DataContractSerializer. It consists of all types needed for serializing the QueryableDataProvider. For this purpose we created a new QueryablePivotSerializationHelper class which has a static member - KnownTypes.

Example 3: Specifying the KnownTypes

public class QueryableProviderSerializer: DataProviderSerializer 
{ 
    public override IEnumerable<Type> KnownTypes 
    { 
        get  
        { 
            return QueryablePivotSerializationHelper.KnownTypes; 
        } 
    } 
} 

Serialize and Deserialize

The final step is to serialize and deserialize the data provider.

Example 4: Serialize and Deserialize the Data Provider

string lastSerializedProvider; 
 
//serialization 
QueryableProviderSerializer serializer = new QueryableProviderSerializer(); 
this.lastSerializedProvider = serializer.Serialize(this.PivotGrid.DataProvider); 
 
//deserialization 
QueryableProviderSerializer serializer = new QueryableProviderSerializer(); 
serializer.Deserialize(this.PivotGrid.DataProvider, this.lastSerializedProvider); 

See Also

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