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QueryStringParameter Constructor (String, TypeCode, String)

Initializes a new named and strongly typed instance of the QueryStringParameter class, using the specified string to identify which query-string field to bind to.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

public QueryStringParameter(
	string name,
	TypeCode type,
	string queryStringField
)

Parameters

name
Type: System.String

The name of the parameter.

type
Type: System.TypeCode

The type that the parameter represents. The default is Object.

queryStringField
Type: System.String

The name of the query-string field that the parameter object is bound to. The default is an empty string ("").

A QueryStringParameter object that is created by using the QueryStringParameter constructor is initialized with the specified parameter name, the parameter type, and a string that identifies the query-string field that the parameter binds to. The Direction and ConvertEmptyStringToNull properties are initialized with default values.

The following example shows how to create a QueryStringParameter object by using the QueryStringParameter constructor and add it to an AccessDataSource control's FilterParameters collection. A GridView control displays data if the employee and country query-string fields are passed with the request and if they have valid values.

<%@ Page language="C#"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
private void Page_Load(object sender, System.EventArgs e)
{
  QueryStringParameter countryFilter =
    new QueryStringParameter("country", TypeCode.String, "country");

  MyAccessDataSource.FilterParameters.Add(countryFilter);
}
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="Form1" method="post" runat="server">

      <!-- Use a Query String with country=USA -->
      <asp:gridview
        id ="GridView1"
        runat="server"
        datasourceid="MyAccessDataSource" />

<!-- Security Note: The AccessDataSource uses a QueryStringParameter,
     Security Note: which does not perform validation of input from the client.
     Security Note: To validate the value of the QueryStringParameter, handle the Selecting event. -->

      <asp:accessdatasource
        id="MyAccessDataSource"
        runat="server"
        datafile="Northwind.mdb"
        selectcommand="SELECT EmployeeID, LastName, Address, PostalCode, Country FROM Employees"
        filterexpression="Country = '{0}'">
      </asp:accessdatasource>
    </form>
  </body>
</html>

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0
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