Architectural Overview


Custom Business Objects

A Custom Business Object (CBO) is essentially a blueprint, or representation, of an object that is important to the application. In DotNetNuke, an example of a CBO is an instance of the DotNetNuke.Services .FileSystem.FileInfo class in /components/FileSystem/FileInfo.vb. An instance of this class contains information about a single file as shown in Listing 7-2.

Listing 7-2: The FileInfo CBO Class

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 <XmlRoot("file", IsNullable:=False)> Public Class FileInfo     Private _FileId As Integer     Private _PortalId As Integer     Private _FileName As String     Private _Extension As String     Private _Size As Integer     Private _Width As Integer     Private _Height As Integer     Private _ContentType As String     Private _Folder As String     <XmlIgnore()> Public Property FileId() As Integer         Get             Return _FileId         End Get         Set(ByVal Value As Integer)             _FileId = Value         End Set     End Property     <XmlIgnore()> Public Property PortalId() As Integer         Get             Return _PortalId         End Get         Set(ByVal Value As Integer)             _PortalId = Value         End Set     End Property     <XmlElement("filename")> Public Property FileName() As String         Get             Return _FileName         End Get         Set(ByVal Value As String)             _FileName = Value         End Set     End Property     <XmlElement("extension")> Public Property Extension() As String         Get             Return _Extension         End Get         Set(ByVal Value As String)             _Extension = Value         End Set     End Property     <XmlElement("size")> Public Property Size() As Integer         Get             Return _Size         End Get         Set(ByVal Value As Integer)             _Size = Value         End Set     End Property     <XmlElement("width")> Public Property Width() As Integer         Get             Return _Width         End Get         Set(ByVal Value As Integer)             _Width = Value         End Set     End Property     <XmlElement("height")> Public Property Height() As Integer         Get             Return _Height         End Get         Set(ByVal Value As Integer)             _Height = Value         End Set     End Property     <XmlElement("contenttype")> Public Property ContentType() As String         Get             Return _ContentType         End Get         Set(ByVal Value As String)             _ContentType = Value         End Set     End Property     <XmlElement("folder")> Public Property Folder() As String         Get             Return _Folder         End Get         Set(ByVal Value As String)             _Folder = Value         End Set     End Property End Class 
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The FileInfo class has no methods, only properties. This is an important distinction to recognize — CBOs only have properties. The methods to manage the CBO are in a CBO Controller class specific to the CBO. A CBO Controller class contains the business logic necessary to work with its associated CBO class. For example, there is a FileController class in /components/FileSystem/FileController.vb that contains business logic for the FileInfo CBO. For the sake of the core File Manager module, the FileInfo data is stored in the database. Therefore, the FileController class contains the logic necessary to hydrate the FileInfo object (or a collection of FileInfo objects) with data retrieved from the database.

CBO Hydrator

One powerful core service is the CBO Hydrator, which is located in the CBO class in /components/ Shared/CBO.vb. It is a collection of methods that provide a centralized means of hydrating a CBO or a collection of CBOs.

Figure 7-2 shows how a CBO Controller class makes a call to the CBO Hydrator by sending in an open DataReader and the type of object to fill. Depending on the method called within the CBO Hydrator, it returns either a single hydrated object or a collection of hydrated objects. When the CBO Hydrator fills an object's properties, it discovers the properties of the CBO using reflection. Then it caches the properties that it has discovered so that the next time an object of the same type is hydrated, the properties won't need to be discovered. Instead, they can be pulled from the cache.

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Figure 7-2

To hydrate a collection of CBOs, use the DotNetNuke.Common.Utilities.CBO.FillCollection method. The method accepts an IDataReader and a type as input parameters. It returns an ArrayList of objects of the type specified in the objType parameter. For example, the code-behind for the Portals module ($AppRoot/admin/Portal/Portals.ascx.vb) needs a collection of PortalInfo objects so it can display a list of Portals in the portal module's rendered output. The code-behind calls DotNetNuke.Entities.Portals .PortalController.GetPortals() to get an ArrayList of PortalInfo objects. That ArrayList is filled by the DotNetNuke.Common.Utilities.CBO.FillCollection method, which converts an iDataReader object (from a database query) into a collection of hydrated PortalInfo objects. Here's the DotNetNuke .Common.Utilities.CBO.FillCollection method signature:

 Public Shared Function FillCollection(ByVal dr As IDataReader, ByVal objType As _ Type) As ArrayList 

To hydrate a single CBO rather than a collection, use the CBO.FillObject method. It accepts the same input parameters, but returns a single object. For example, in the code-behind for the Site Settings module ($AppRoot/Admin/Portal/SiteSettings.ascx.vb), the control needs a PortalInfo object to display the portal settings in the module's rendered output. The code-behind gets the PortalInfo object from a call to DotNetNuke.Entities.Portals.PortalController.GetPortal. The GetPortal method uses the DotNetNuke.Common.Utilities.CBO.FillObject method to convert an iDataReader object (from a database query) into a hydrated PortalInfo object. Following is the method signature for DotNetNuke.Common.Utilities.CBO.FillObject:

 Public Shared Function FillObject(ByVal dr As IDataReader, ByVal _ objType As Type) As Object 

Using the CBO Hydrator

The FileController shown in Listing 7-3 is an example of a CBO Controller that utilizes the CBO Hydrator.

Listing 7-3: The FileController CBO Controller Class

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 Public Class FolderController     Public Function GetFoldersByPortal(ByVal PortalID As Integer) As ArrayList         Return _         CBO.FillCollection(DataProvider.Instance().GetFoldersByPortal(PortalID), _         GetType(Services.FileSystem.FolderInfo))     End Function     Public Function GetFolder(ByVal PortalID As Integer, ByVal FolderPath As _     String) As FolderInfo         Return CType(CBO.FillObject(DataProvider.Instance().GetFolder(PortalID, _         FolderPath), GetType(Services.FileSystem.FolderInfo)), FolderInfo)     End Function     Public Function GetFolder(ByVal PortalID As Integer, ByVal FolderID As Integer)     As ArrayList         Return CBO.FillCollection(DataProvider.Instance().GetFolder(PortalID, _         FolderID), GetType(Services.FileSystem.FolderInfo))     End Function     Public Function AddFolder(ByVal objFolderInfo As FolderInfo) As Integer         ReturnDataProvider.Instance().AddFolder(objFolderInfo.PortalID, _         objFolderInfo.FolderPath)     End Function     Public Sub UpdateFolder(ByVal objFolderInfo As FolderInfo)         DataProvider.Instance().UpdateFolder(objFolderInfo.PortalID, _         objFolderInfo.FolderID, objFolderInfo.FolderPath)     End Sub     Public Sub DeleteFolder(ByVal PortalID As Integer, ByVal FolderPath As String)         DataProvider.Instance().DeleteFolder(PortalID, FolderPath)     End Sub End Class 
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Using the CBO Hydrator significantly reduces the amount of code needed to fill an object or collection of objects. Without using the CBO Hydrator, you would have to code at least one line per CBO property to fill that object with the contents of a DataReader. Listing 7-4 is an example of filling a single FileInfo object without using the CBO Hydrator.

Listing 7-4: Traditional Method of Filling an Object

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 Dim dr As IDataReader Try     dr = DataProvider.Instance().GetFolder(PortalID, FolderPath)     Dim f As New FileInfo     f.ContentType = Convert.ToString(dr("ContentType"))     f.Extension = Convert.ToString(dr("Extension"))     f.FileId = Convert.ToInt32(dr("FileId"))     f.FileName = Convert.ToString(dr("FileName"))     f.Folder = Convert.ToString(dr("Folder"))     f.Height = Convert.ToInt32(dr("Height"))     f.PortalId = Convert.ToInt32(dr("PortalId"))     f.Size = Convert.ToInt32(dr("Size"))     f.Width = Convert.ToInt32(dr("Width"))     Return f Finally     If Not dr Is Nothing Then         dr.Close()     End If End Try 
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Instead of writing all of that code, the CBO Hydrator can be used to greatly simplify things. The code in Listing 7-5 does the same thing as the code in Listing 7-4, except it uses the CBO Hydrator.

Listing 7-5: Filling an Object Using the CBO Hydrator

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 Return CType(CBO.FillObject(DataProvider.Instance().GetFolder(PortalID, _         FolderPath), GetType(Services.FileSystem.FolderInfo)), FolderInfo) 
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Custom Business Objects are used throughout DotNetNuke to create a truly object-oriented design. The objects provide for type safety and enhance performance by allowing code to work with disconnected collections rather than with DataReaders, DataTables, or DataSets. Use the CBO Hydrator whenever possible to reduce the amount of coding and to enhance the maintainability of the application.




Professional DotNetNuke 4.0 (c) Open Source Web Application Framework for ASP. NET 4.0
Professional DotNetNuke 4: Open Source Web Application Framework for ASP.NET 2.0 (Programmer to Programmer)
ISBN: 0471788163
EAN: 2147483647
Year: 2006
Pages: 182

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