ASP.NET 4 Unleashed

Creating a Custom ExpressionBuilder

An ExpressionBuilder class generates one expression from another expression. Typically, you use an ExpressionBuilder to look up a particular value given a particular key.

The ASP.NET Framework includes the following ExpressionBuilder classes:

• AppSettingsExpressionBuilder— Retrieves values from the appSettings section of the web configuration file.

• ConnectionStringsExpressionBuilder— Retrieves values from the connectionStrings section of the web configuration file.

• ResourceExpressionBuilder— Retrieves values from resource files.

The ConnectionStringsExpressionBuilder has been used throughout this book whenever a connection string has needed to be retrieved.

You use the following syntax when working with ...