ASP.NET 2.0: A Developeramp;#039;s Notebook [Electronic resources] نسخه متنی

7.1. Personalize Your Application

Note: Use the Profile object to remember your
users' preferences.

Chapter 5 introduces
the new ASP.NET Membership Provider
and shows you how to use it to manage users easily. Using the new
Membership Provider makes managing user logins straightforward.
However, the membership feature does not store information about the
users it lists, such as their preferences for themes, their shipping
addresses, or lists of previous purchases.

To remember a user's preferences, you can use the
new Profile service (exposed via the Profile object) in ASP.NET 2.0.
Think of the Profile service as a mechanism to persistently store a
user's information, similar to the Session object.
Unlike a Profile object, however, a Session object is valid only for
the duration of a session; after the session has expired, the Session
object is deleted. The Profile service, however, retains its
information until you explicitly remove it from the data store.

Moreover, the Profile object has several advantages over the Session
object, such as:

Profile object data is persisted in data stores, whereas Session
variables are saved in memory.

Profile object properties are strongly typed, unlike Session
variables, which are stored as Objects and typecast during runtime.

Profile properties are loaded only when they're
needed, unlike Session variables, which are all loaded whenever any
one of them is accessed.

In ASP.NET 2.0, the new Profile object allows user's
data to be persisted in a much more efficient manner.

7.1.1. How do I do that?

If you want to use the Profile object to store
personalized information about your users, you need a way to identify
users so their usernames can act as keys to the information stored in
the data store. In this lab, you will build an application that
prompts the user to save her name when she first visits your site.
Subsequently, when she visits the page again, you will be able to
retrieve her name from the Profile object.

Launch Visual Studio 2005 and create a new web site project. Name the
project C:\ASPNET20\chap07-Profile.

Drag and drop a Panel control onto the default Web Form and add a 2 3
table (Layout Insert
Table) into the Panel control. Populate the form with the controls
shown in Figure 7-1.

Figure 7-2. Populating the default page with all the controls

The default Web Form will prompt the user to enter her name when she
first visits the page. The next time the user visits the page, the
application will be able to remember her name. You will use the
Profile object to save the user's name. To use the
Profile object, you first need to add a web configuration file to
your project. Right-click on the project name in Solution Explorer,
select Add New Item..., and select Web Configuration File from the
Template pane of the Add New Item dialog.

Add the <profile> element to the
Web.config file as follows:

<system.web>
<profile>
<properties>
<add name="FirstName" type="System.String"/>
<add name="LastName" type="System.String"/>
</properties>
</profile>
...

You have defined two Profile properties, FirstName
and LastName, which will be used to store a
user's first and last name, respectively. You have
also specified the data types to be used for the properties. You can
use any type that is available in the framework (so long as they are
serializable). To use either of the two Profile properties, simply
prefix the property name with the keyword Profile.
That is, Profile.FirstName and
Profile.LastName.

Attributes in the Profile Property

Besides the name and the type attribute (any .NET data
type; the default is string), you can also specify the following
attributes:

readOnly

Indicates whether the property is read-only.

serializeAs

Represents how the property value should be stored in the database.
Possible values are String (default),
Xml, Binary, and
ProviderSpecific.

provider

The name of the profile provider to use.

defaultValue

The default value of the property.

allowAnonymous

Whether the property can store values by anonymous users.

Double-click the default Web Form to switch to its code-behind page.
In the Page_Load event, first check to see if the FirstName property
is nonempty. If it is nonempty, you will retrieve the first and last
name of the user from the Profile properties. If it is empty, you can
assume this is the first time the user is visiting the page, and you
can show the Panel control to allow the user to enter her first and
last name.

Protected Sub Page_Load(ByVal sender As Object, _
ByVal e As System.EventArgs) _
Handles Me.Load
If Profile.FirstName <> " Then
Panel1.Visible = False
Response.Write("Welcome back, " & _
Profile.FirstName & ", " & _
Profile.LastName)
Else
Panel1.Visible = True
End If
End Sub

When the user clicks the Save button, you save the first and last
names by simply assigning them to the Profile properties. Code the
Save button as:

Protected Sub btnSave_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) _
Handles btnSave.Click
' save the profile 
Profile.FirstName = txtFirstName.Text
Profile.LastName = txtLastName.Text
Response.Write("Thank you, " & _
txtFirstName.Text & ", " & txtLastName.Text)
End Sub

To test the application, press F5. Figure 7-2 shows
what happens when the user loads the Web Form for the first time. The
user can then enter her name and click Save to save her name in the
Profile object. When the user comes back to visit the page again, she
will be greeted with a welcome message, instead of having to reenter
her name (see Figure 7-3).

Figure 7-3. Loading the page for the first time

Figure 7-4. Subsequent visit by the user

7.1.2. What just happened?

When you run the application, the user's first and
last names are saved in the Profile properties. So where are these
values stored?

ASP.NET 2.0 uses a Profile Provider to store the data saved in the
Profile object. By default, the SQL Server 2005 Express Provider is
used.

To examine the values stored by the Profile object, double-click the
ASPNETDB.MDF file located under the
App_Data folder in your project.

You should now see the ASPNETDB.MDF database
under the Data Connections item in Server Explorer (see Figure 7-4). Expand the Tables node to view the list of
tables within this database.

Figure 7-5. Examining the aspnetdb database

Right-click on the aspnet_Profile table and select Show Table Data.
You should now be able to see the values stored in the table (see
Figure 7-5).

Figure 7-6. Examining the aspnet_Profile table

Note the UserID field of the aspnet_Profile table. It is used to
uniquely identify the Profile object associated with a particular
user for this application. If you further examine the aspnet_Users
table (see Figure 7-6), the UserID field has a
corresponding ApplicationID field (that identifies the application)
and a UserName field (that identifies the user).

Figure 7-7. Examining the aspnet_Users table

Notice that the UserName is "WINXP2\Wei-Meng
Lee." For this application, you are using the
default Windows authentication for your ASP.NET application.
Therefore, you should see your own Windows login name.

7.1.3. What about...

...grouping related Profile properties?

Suppose you want to save the address of a
user. Instead of using the following structure:

Profile.Line1 = "
Profile.Line2 = "
Profile.State = "
Profile.Zip = "

it would be more logical to organize all related information into a
group, like this:

Profile.Address.Line1 = "
Profile.Address.Line2 = "
Profile.Address.State = "
Profile.Address.Zip = "

To do so, simply use the <group> element in
Web.config:

<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
<system.web>
<profile>
<properties>
<add name="FirstName" type="System.String" />
<add name="LastName" type="System.String" />
<add name="LastLoginTime" type="System.DateTime" />
<group name="Address">
<add name="Line1" type="System.String" />
<add name="Line2" type="System.String" />
<add name="State" type="System.String" />
<add name="Zip" type="System.String" />
</group>
</properties>
</profile>
</system.web>
</configuration>

7.1.4. Where can I learn more?

You can write your own Profile Provider if you
do not want to use the one provided by
Microsoft. For example, you may wish to persist the Profile
properties in an XML file instead of a SQL Server database. For more
information on the ASP.NET 2.0 Provider Model, check out these two
articles by Rob Howard:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspnet/html/asp02182004.asp

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspnet/html/asp04212004.asp