ConnectionStringsExpressionBuilder Class

 

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

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

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

Public Class ConnectionStringsExpressionBuilder
	Inherits ExpressionBuilder

NameDescription
System_CAPS_pubmethodConnectionStringsExpressionBuilder()

Initializes a new instance of the ConnectionStringsExpressionBuilder class.

NameDescription
System_CAPS_pubpropertySupportsEvaluate

Returns a value indicating whether an expression can be evaluated in a page that is not compiled.(Overrides ExpressionBuilder.SupportsEvaluate.)

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_pubmethodEvaluateExpression(Object, BoundPropertyEntry, Object, ExpressionBuilderContext)

Returns a value from the <connectionStrings> section of the Web.config file.(Overrides ExpressionBuilder.EvaluateExpression(Object, BoundPropertyEntry, Object, ExpressionBuilderContext).)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetCodeExpression(BoundPropertyEntry, Object, ExpressionBuilderContext)

Returns a code expression to evaluate during page parsing.(Overrides ExpressionBuilder.GetCodeExpression(BoundPropertyEntry, Object, ExpressionBuilderContext).)

System_CAPS_pubmethodSystem_CAPS_staticGetConnectionString(String)

Returns a connection string from the <connectionStrings> section of the Web.config file.

System_CAPS_pubmethodSystem_CAPS_staticGetConnectionStringProviderName(String)

Returns the connection string provider from the <connectionStrings> section of the Web.config file.

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodParseExpression(String, Type, ExpressionBuilderContext)

Returns an object that represents the parsed expression.(Overrides ExpressionBuilder.ParseExpression(String, Type, ExpressionBuilderContext).)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

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
Available since 2.0

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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