ConnectionStringsExpressionBuilder Class
Retrieves, or generates code to retrieve, values from the <connectionStrings> section of the Web.config file.
System.Web.Compilation.ExpressionBuilder
System.Web.Compilation.ConnectionStringsExpressionBuilder
Assembly: System.Web (in System.Web.dll)
The ConnectionStringsExpressionBuilder type exposes the following members.
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ConnectionStringsExpressionBuilder | Initializes a new instance of the ConnectionStringsExpressionBuilder class. |
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SupportsEvaluate | Returns a value indicating whether an expression can be evaluated in a page that is not compiled. (Overrides ExpressionBuilder.SupportsEvaluate.) |
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Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
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EvaluateExpression | Returns a value from the <connectionStrings> section of the Web.config file. (Overrides ExpressionBuilder.EvaluateExpression(Object, BoundPropertyEntry, Object, ExpressionBuilderContext).) |
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Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
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GetCodeExpression | Returns a code expression to evaluate during page parsing. (Overrides ExpressionBuilder.GetCodeExpression(BoundPropertyEntry, Object, ExpressionBuilderContext).) |
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GetConnectionString | Returns a connection string from the <connectionStrings> section of the Web.config file. |
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GetConnectionStringProviderName | Returns the connection string provider from the <connectionStrings> section of the Web.config file. |
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GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
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GetType | Gets the Type of the current instance. (Inherited from Object.) |
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MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
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ParseExpression | Returns an object that represents the parsed expression. (Overrides ExpressionBuilder.ParseExpression(String, Type, ExpressionBuilderContext).) |
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ToString | 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="C#" %> <!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>
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
