This blog is the third in a series looking at the new features in the next release of DotNetNuke, and focusses on the new IHydratable interface. There are two pieces to this interface, which is designed to make it easier to hydrate your business objects but still take advantage of some of the performance strategies introduced recently (4.4).
Prior to 4.4 most business objects were hydrated by passing a DataReader to the CBO class's FillObject or FillCollection methods. These methods use reflection to set the various properties of a business object and while this is convenient it is not neccesasrily the fastest way to hydrate business objects.
In 4.4 we focussed on performance improvements and a number of the core business controller classes were modifed to use custom hydrators to fill the business objects in order to improve the performance of DotNetNuke. You can see examples of this in TabController, PortalController and ModuleController. The problem with this approach is that the developer has to manage the DataReader - it is critical that the DataReader gets closed when it is finished with or the underlying connection to the database remains open. By comparison, the CBO class manages these connections and ensures they are closed correctly.
Enter IHydratable. This interface provides a property - KeyID (more in a later Blog) and a method - Fill. If a business entity class implements this interface, then the developer can take advantage of both the performance gain of custom hydration AND the ease-of-use of the CBO class's DataReader management (You can have your cake and eat it too).
How is this achieved? The CBO method that hydrates the object (CreateObject) first checks if the object implements the IHydratable interface. If it does it calls the Fill method in the business object - if it doesn't then it uses refection as before.
Dim objObject As Object = Activator.CreateInstance(objType)
If TypeOf objObject Is IHydratable Then
'Create Object and Use IHydratable's Fill
Dim objHydratable As IHydratable = TryCast(objObject, IHydratable)
If objHydratable IsNot Nothing Then
.... Previous code that uses reflection is here
As an example here is the Fill method for Announcements:
Public Sub Fill(ByVal dr As IDataReader) Implements IHydratable.Fill
ItemId = Convert.ToInt32(Null.SetNull(dr.Item("ItemID"), ItemId))
ModuleId = Convert.ToInt32(Null.SetNull(dr.Item("ModuleID"), ModuleId))
Title = Convert.ToString(Null.SetNull(dr.Item("Title"), Title))
Url = Convert.ToString(Null.SetNull(dr.Item("Url"), Url))
ViewOrder = Convert.ToInt32(Null.SetNull(dr.Item("ViewOrder"), ViewOrder))
Description = Convert.ToString(Null.SetNull(dr.Item("Description"), Description))
ImageSource = Convert.ToString(Null.SetNull(dr.Item("ImageSource"), ImageSource))
CreatedByUser = Convert.ToInt32(Null.SetNull(dr.Item("CreatedByUser"), CreatedByUser))
CreatedDate = Convert.ToDateTime(Null.SetNull(dr.Item("CreatedDate"), CreatedDate))
TrackClicks = Convert.ToBoolean(Null.SetNull(dr.Item("TrackClicks"), TrackClicks))
NewWindow = Convert.ToBoolean(Null.SetNull(dr.Item("NewWindow"), NewWindow))
PublishDate = Convert.ToDateTime(Null.SetNull(dr.Item("PublishDate"), PublishDate))
ExpireDate = Convert.ToDateTime(Null.SetNull(dr.Item("ExpireDate"), ExpireDate))