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ConnectionStringsExpressionBuilder Class

Retrieves, or generates code to retrieve, values from the <connectionStrings> section of the Web.config file.

System.Object
  System.Web.Compilation.ExpressionBuilder
    System.Web.Compilation.ConnectionStringsExpressionBuilder

Namespace:  System.Web.Compilation
Assembly:  System.Web (in System.Web.dll)

'Declaration
Public Class ConnectionStringsExpressionBuilder _
	Inherits ExpressionBuilder

The ConnectionStringsExpressionBuilder type exposes the following members.

  NameDescription
Public methodConnectionStringsExpressionBuilderInitializes a new instance of the ConnectionStringsExpressionBuilder class.
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  NameDescription
Public propertySupportsEvaluateReturns a value indicating whether an expression can be evaluated in a page that is not compiled. (Overrides ExpressionBuilder.SupportsEvaluate.)
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  NameDescription
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Public methodEvaluateExpressionReturns a value from the <connectionStrings> section of the Web.config file. (Overrides ExpressionBuilder.EvaluateExpression(Object, BoundPropertyEntry, Object, ExpressionBuilderContext).)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetCodeExpressionReturns a code expression to evaluate during page parsing. (Overrides ExpressionBuilder.GetCodeExpression(BoundPropertyEntry, Object, ExpressionBuilderContext).)
Public methodStatic memberGetConnectionStringReturns a connection string from the <connectionStrings> section of the Web.config file.
Public methodStatic memberGetConnectionStringProviderNameReturns the connection string provider from the <connectionStrings> section of the Web.config file.
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodParseExpressionReturns an object that represents the parsed expression. (Overrides ExpressionBuilder.ParseExpression(String, Type, ExpressionBuilderContext).)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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The ConnectionStringsExpressionBuilder class provides access to values in the <connectionStrings> section of the Web.config file. The <connectionStrings> section of the Web.config file contains connection string values in name/value pairs.

A connection string value is retrieved by assigning an expression of the form

<%$ ConnectionStrings: secureConnectionString %>

to a control property. The part of the expression before the colon (:) designates the type of expression to be retrieved, and the part after the colon signifies the name of the connection string. The preceding expression would retrieve the following value from the Web.config file.

<connectionStrings>

<add name="secureConnectionString" connectionString="Data

Source=localhost;Integrated Security=SSPI;Initial

Catalog=Northwind;" providerName="System.Data.SqlClient" />

</connectionStrings>

When the page parser encounters an expression with the prefix ConnectionStrings, it creates an instance of the ConnectionStringsExpressionBuilder class to handle the expression.

If the expression is encountered in a page that will be compiled, the ConnectionStringsExpressionBuilder object generates code that retrieves the specified connection string from the Web.config file. If the expression is encountered in a page that will not be compiled, the ConnectionStringsExpressionBuilder object returns the value from the Web.config file when the page is parsed.

The following code example demonstrates how to declaratively use a SqlDataSource control to retrieve data from a computer running Microsoft SQL Server and display it in a GridView control.

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <asp:SqlDataSource
          id="SqlDataSource1"
          runat="server"
          DataSourceMode="DataReader"
          ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
          SelectCommand="SELECT FirstName, LastName, Title FROM Employees">
      </asp:SqlDataSource>

      <asp:GridView
          id="GridView1"
          runat="server"
          DataSourceID="SqlDataSource1">
      </asp:GridView>

    </form>
  </body>
</html>

The code retrieves the following connection string from the Web.config file.

<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">

<connectionStrings>

<add name="MyNorthwind" connectionString="Data

Source=localhost;Integrated Security=SSPI;Initial

Catalog=Northwind;" providerName="System.Data.SqlClient" />

</connectionStrings>

</configuration>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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