First Look At Asp Net v2.0 [Electronic resources] نسخه متنی

Writing a Personalization Provider

When the ASP.NET team set out to build the ASP.NET Personalization system, the most challenging aspect of the design was the data model. They wanted to allow for the maximum amount of flexibility and extensibility. They initially examined several approaches with schemas within the database to describe properties and their types but found that this created very deep tables that couldn't efficiently be used without an intimate knowledge of the schema. They were also concerned that this approach would not perform well. They ideally desired for the data model to use the columns for each type of data, for example, a FirstName column of type nvarchar(256). While this gave them the best performance, it was the most difficult to extend; extensibility would have consisted of adding columns and tables.

They decided on an approach that gave the end developer the most flexibility; hence the provider design pattern was created. The provider pattern allows you to store or use data in any shape and use the friendly, easy-to-use Personalization APIs. In fact, they want you to write providers. Most developers already have lots of user data. Rather than forcing you to use a new data model, the provider pattern allows the data to remain in whatever format you desire, but at the same time you can easily expose that data through the Personalization APIs.

All providers must implement IProvider as well as the specific feature interface. For Personalization this is System.Configuration.Settings .ISettingsProvider. Earlier in the chapter we discussed a Personalization provider for the ASP.NET Forums; Listing 7.13 shows a simple implementation of that Personalization provider.

Listing 7.13 Sample Personalization Provider

Imports System
Imports System.Web
Imports System.Collections
Imports System.Collections.Specialized
Imports System.Configuration.Provider
Imports System.Configuration.Settings
Imports System.Web.Personalization
Imports System.Data
Imports System.Data.SqlClient
Namespace Forums
Public Class ForumsPersonalizationProvider
Implements IProvider, ISettingsProvider
Public Sub Initialize(name As String, _
config As NameValueCollection) _
Implements IProvider.Initialize
' Used to set the name and any
' config data from configuration
End Sub
' Returns property values
Public Sub GetPropertyValues (userName As String, _
Properties As SettingsPropertyCollection) _
Implements ISettingsProvider.GetPropertyValues
Dim connection As SqlConnection
Dim command As SqlCommand
connection = New SqlConnection("connection string")
command = New SqlCommand("SELECT * FROM Users " _
& "WHERE Username = '" _
& userName & "'", connection)
Dim reader As SqlDataReader
connection.Open()
reader = command.ExecuteReader()
While reader.Read()
properties("Email").PropertyValue = reader("Email")
properties("FakeEmail").PropertyValue = reader("FakeEmail")
properties("Trusted").PropertyValue = reader("Trusted")
properties("DateCreated").PropertyValue = reader("DateCreated")
properties("TotalPosts").PropertyValue = reader("TotalPosts")
End While
connection.Close()
End Sub
Public Sub SavePropertyValues (userName As String, _
properties As SettingsPropertyCollection, _
isAuthenticated As Boolean) _
Implements ISettingsProvider.SavePropertyValues
End Sub
Public Property ApplicationName() As String _
Implements ISettingsProvider.ApplicationName
Get
return "/"
End Get
Set (ByVal Value As String)
End Set
End Property
Public ReadOnly Property Name() As String _
Implements IProvider.Name
Get
return "ForumsProvider"
End Get
End Property
End Class
End Namespace

Once compiled, we can use this provider by specifying it in our web.config, as demonstrated in Listing 7.14.

Listing 7.14 Adding the Custom Provider

<configuration>
<system.web>
<personalization>
<providers>
<add name="ForumsProvider"
type="Forums.ForumsPersonalizationProvider,
ForumsPersonalizationProvider"
applicationName="/" />
</providers>
<profile>
<property name="FirstName"/>
<property name="LastName" />
<property name="Email" provider="ForumsProvider" />
<property name="FakeEmail" provider="ForumsProvider" />
<property name="Trusted" type="System.Boolean"
provider="ForumsProvider" />
<property name="DateCreated" type="System.DateTime"
provider="ForumsProvider" />
<property name="TotalPosts" type="System.Int32"
provider="ForumsProvider" />
</profile>
</personalization>
</system.web>
</configuration>

Finally, we can then write pages that display the property values (see Listing 7.15).

Listing 7.15 Using the Custom Provider

Your email address is: <% =Profile.Email %>
<P>
Your fake email address is: <% =Profile.FakeEmail %>
<P>
Your total posts are: <% =Profile.TotalPosts %>
<P>
Your account was created:
<% =Profile.DateCreated.ToString("MM/dd/yy mm:ss")%>

Providers allow you to fully plug in to the APIs exposed by ASP.NET. You can take full control over what happens when those APIs are used within your application.