New Ways to Handle Data

Figure 4-38

Connection Strings

An interesting point about the previous example is that we decided to store the connection string directly in the web.config file instead of hard-coding the connection string directly in the code of the page. This is always a good idea because it is more secure and makes your connection strings easier to manage. If you followed the previous steps as instructed, Visual Studio placed the connection string in the web.config for you. It then appears as shown in Listing 4-29.

Listing 4-29: Storing the connection string in the web.config

<?xml version=”1.0”?> <configuration>

<connectionStrings>

<add name=”AppConnectionString1” connectionString=”Provider=SQLOLEDB.1; Data Source=HOME01;User ID=sa;Initial Catalog=Northwind;

Persist Security Info=False” providerName=”System.Data.OleDb” />

(continued)

123

Chapter 4

Listing 4-29: (continued)

</connectionStrings>

<system.web>

...

</system.web>

</configuration>

A <connectionStrings> section is created in the web.config file. Placed within the <connection Strings> section is a simple <add> element that contains a couple of attributes. The first attribute is the name attribute. This is the name that is used to uniquely identify this connection string in your ASP.NET pages because it is possible to have multiple connection strings within your web.config file. In this case, the connection string is named AppConnectionString1.

The next attribute is the connectionString attribute. The value given here is the full connection string. The last attribute is the providerName attribute, which simply contains the name of the provider that you are using to connect to the data store.

Looking at the SqlDataSource code in the ASP.NET page utilizing this stored connection string in Listing 4-30, you can see that it is rather simple to use the information stored in the web.config file.

Listing 4-30: Using the connection string stored in the web.config file

<asp:SqlDataSource ID=”SqlDataSource1” Runat=”server” SelectCommand=”SELECT [Customers].* FROM [Customers]” ConnectionString=”<%$ ConnectionStrings:AppConnectionString1 %>” ProviderName=”<%$ ConnectionStrings:AppConnectionString1.providername %>”> </asp:SqlDataSource>

You can see here that the connection string value is retrieved using <%$ ConnectionStrings: AppConnectionString1 %> and that the provider name attribute is accessed using <%$ ConnectionStrings:AppConnectionString1.providername %>.

Although this was done automatically for you by Visual Studio, you can just as easily do this yourself within the ASP.NET applications that you code.

Summar y

This chapter introduced some of the new ways in which you can work with data in ASP.NET 2.0. The latest version of ASP.NET provides you with an outstanding new collection of data source controls that you can use to retrieve and manipulate data held in a wide variety of different data stores.

124

New Ways to Handle Data

The new data source controls, SqlDataSource, AccessDataSource, XmlDataSource, ObjectDataSource, DataSetDataSource, and SiteMapDataSource, are powerful and easy to use. They require little effort on the part of the developer, but at the same time, they are rather extensible and can be modified for almost any purpose when it comes to working with the data that is running your applications.

In addition to the data source controls, this chapter took a look at some of the new data-bound server controls such as the GridView and the DetailsView controls. These are outstanding new controls that you can use with the new data source controls. The GridView is an enhanced DataGrid that has built-in paging and sorting, whereas the DetailsView control enables you to drill down into a particular data piece in a logical manner.

125