ControlParameter Class

Reference

Definition

Namespace:: System.Web.UI.WebControls

Assembly:: System.Web.dll

Important

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Binds the value of a property of a Control to a parameter object.

public ref class ControlParameter : System::Web::UI::WebControls::Parameter

public class ControlParameter : System.Web.UI.WebControls.Parameter

type ControlParameter = class
    inherit Parameter

Public Class ControlParameter
Inherits Parameter

Inheritance: Object

Parameter
ControlParameter

Examples

The following code example demonstrates how to use a ControlParameter object to bind data displayed in a ListBox control to the selected value of a DropDownList control in a declarative scenario. The ControlParameter object is added to the SelectParameters collection of the SqlDataSource control on the form, and corresponds to the "@Title" placeholder text in the SelectCommand property.

<!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">

      <p><asp:dropdownlist
          id="DropDownList1"
          runat="server"
          autopostback="True">
          <asp:listitem selected="True">Sales Representative</asp:listitem>
          <asp:listitem>Sales Manager</asp:listitem>
          <asp:listitem>Vice President, Sales</asp:listitem>
      </asp:dropdownlist></p>

      <asp:sqldatasource
          id="SqlDataSource1"
          runat="server"
          connectionstring="<%$ ConnectionStrings:MyNorthwind%>"
          selectcommand="SELECT LastName FROM Employees WHERE Title = @Title">
          <selectparameters>
              <asp:controlparameter name="Title" controlid="DropDownList1" propertyname="SelectedValue"/>
          </selectparameters>
      </asp:sqldatasource>

      <p><asp:listbox
          id="ListBox1"
          runat="server"
          datasourceid="SqlDataSource1"
          datatextfield="LastName">
      </asp:listbox></p>

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

<!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">

      <p><asp:dropdownlist
          id="DropDownList1"
          runat="server"
          autopostback="True">
          <asp:listitem selected="True">Sales Representative</asp:listitem>
          <asp:listitem>Sales Manager</asp:listitem>
          <asp:listitem>Vice President, Sales</asp:listitem>
      </asp:dropdownlist></p>

      <asp:sqldatasource
          id="SqlDataSource1"
          runat="server"
          connectionstring="<%$ ConnectionStrings:MyNorthwind%>"
          selectcommand="SELECT LastName FROM Employees WHERE Title = @Title">
          <selectparameters>
              <asp:controlparameter name="Title" controlid="DropDownList1" propertyname="SelectedValue"/>
          </selectparameters>
      </asp:sqldatasource>

      <p><asp:listbox
          id="ListBox1"
          runat="server"
          datasourceid="SqlDataSource1"
          datatextfield="LastName">
      </asp:listbox></p>

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

Remarks

You can use the ControlParameter class to bind the value of a Control property, such as SelectedValue or SelectedIndex, to a parameter that is used in a parameterized SQL query, business object method, or filtering expression.

The ControlParameter class provides two properties in addition to those inherited from the Parameter class: ControlID and PropertyName. The ControlID property identifies which Control instance to bind to and the PropertyName property identifies the public property of the Control from which the ControlParameter class retrieves a value.

Constructors

ControlParameter()	Initializes a new unnamed instance of the ControlParameter class.
ControlParameter(ControlParameter)	Initializes a new instance of the ControlParameter class with values from the specified instance.
ControlParameter(String, DbType, String, String)	Initializes a new instance of the ControlParameter class by using the specified parameter name, database type, control ID, and property name.
ControlParameter(String, String)	Initializes a new named instance of the ControlParameter class, using the specified control name to identify which control to bind to.
ControlParameter(String, String, String)	Initializes a new named instance of the ControlParameter class, using the specified property name and control name to identify which control to bind to.
ControlParameter(String, TypeCode, String, String)	Initializes a new named and strongly typed instance of the ControlParameter class, using the specified property name and control name to identify which control to bind to.

Properties

ControlID	Specifies the name of the control that the ControlParameter object binds to.
ConvertEmptyStringToNull	Gets or sets a value indicating whether the value that the Parameter object is bound to should be converted to `null` if it is Empty. (Inherited from Parameter)
DbType	Gets or sets the database type of the parameter. (Inherited from Parameter)
DefaultValue	Specifies a default value for the parameter, should the value that the parameter is bound to be uninitialized when the Evaluate(HttpContext, Control) method is called. (Inherited from Parameter)
Direction	Indicates whether the Parameter object is used to bind a value to a control, or the control can be used to change the value. (Inherited from Parameter)
IsTrackingViewState	Gets a value indicating whether the Parameter object is saving changes to its view state. (Inherited from Parameter)
Name	Gets or sets the name of the parameter. (Inherited from Parameter)
PropertyName	Gets or sets the property name of the control identified by the ControlID property that the ControlParameter object binds to.
Size	Gets or sets the size of the parameter. (Inherited from Parameter)
Type	Gets or sets the type of the parameter. (Inherited from Parameter)
ViewState	Gets a dictionary of state information that allows you to save and restore the view state of a Parameter object across multiple requests for the same page. (Inherited from Parameter)

Methods

Clone()	Returns a duplicate of the current ControlParameter instance.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Evaluate(HttpContext, Control)	Updates and returns the value of the ControlParameter object.
GetDatabaseType()	Gets the DbType value that is equivalent to the CLR type of the current Parameter instance. (Inherited from Parameter)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
LoadViewState(Object)	Restores the data source view's previously saved view state. (Inherited from Parameter)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
OnParameterChanged()	Calls the OnParametersChanged(EventArgs) method of the ParameterCollection collection that contains the Parameter object. (Inherited from Parameter)
SaveViewState()	Saves the changes to the Parameter object's view state since the time the page was posted back to the server. (Inherited from Parameter)
SetDirty()	Marks the Parameter object so its state will be recorded in view state. (Inherited from Parameter)
ToString()	Converts the value of this instance to its equivalent string representation. (Inherited from Parameter)
TrackViewState()	Causes the Parameter object to track changes to its view state so they can be stored in the control's ViewState object and persisted across requests for the same page. (Inherited from Parameter)

Explicit Interface Implementations

ICloneable.Clone()	Returns a duplicate of the current Parameter instance. (Inherited from Parameter)
IStateManager.IsTrackingViewState	Gets a value indicating whether the Parameter object is saving changes to its view state. (Inherited from Parameter)
IStateManager.LoadViewState(Object)	Restores the data source view's previously saved view state. (Inherited from Parameter)
IStateManager.SaveViewState()	Saves the changes to the Parameter object's view state since the time the page was posted back to the server. (Inherited from Parameter)
IStateManager.TrackViewState()	Causes the Parameter object to track changes to its view state so they can be stored in the control's ViewState object and persisted across requests for the same page. (Inherited from Parameter)

Applies to

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