HtmlInputImage.CausesValidation Property

Definition

Gets or sets a value indicating whether validation is performed when the HtmlInputImage control is clicked.

public:
 virtual property bool CausesValidation { bool get(); void set(bool value); };
public virtual bool CausesValidation { get; set; }
member this.CausesValidation : bool with get, set
Public Overridable Property CausesValidation As Boolean

Property Value

true if validation is performed when the HtmlInputImage control is clicked; otherwise, false. The default value is true.

Examples

The following code example demonstrates how to use the CausesValidation property to prevent page validation from occurring. Notice how the Validate method activates each validation control independently.


<%@ Page Language="C#" AutoEventWireup="True" %>

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

  void SubmitButton_Click(Object sender, ImageClickEventArgs e)
  {

    // Determine which button was clicked.
    switch (((HtmlInputImage)sender).ID)
    {

      case "CityQueryButton":

        // Validate only the controls used for the city query.
        CityReqValidator.Validate();

        // Take the appropriate action if the controls pass validation. 
        if (CityReqValidator.IsValid)
        {
          Message.InnerHtml = "You have chosen to run a query for the following city: " +
             CityTextBox.Value;
        }

        break;

      case "StateQueryButton":

        // Validate only the controls used for the state query.
        StateReqValidator.Validate();

        // Take the appropriate action if the controls pass validation.
        if (StateReqValidator.IsValid)
        {
          Message.InnerHtml = "You have chosen to run a query for the following state: " +
             StateTextBox.Value;
        }

        break;

      default:

        // If the button clicked is not recognized, erase the message on the page.
        Message.InnerHtml = "";

        break;

    }

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
<head>
    <title> HtmlInputImage CausesValidation Example </title>
</head>

<body>

   <form id="form1" runat="server">

      <h3> HtmlInputImage CausesValidation Example </h3>

      <table border="1" cellpadding="10">

         <tr>
            <td>
               <b>Enter city to query.</b> <br />
               <input id="CityTextBox" 
                      type="Text"
                      runat="server"/>
               <asp:RequiredFieldValidator 
                      ID="CityReqValidator"
                      ControlToValidate="CityTextBox"
                      ErrorMessage="<br />Please enter a city."
                      Display="Dynamic"
                      EnableClientScript="False"
                      runat="server"/>
            </td>
            <td valign="bottom">
               <input id="CityQueryButton"
                      alt="City Submit button"
                      type="Image"
                      src="image.jpg"
                      causesvalidation="False"
                      onserverclick="SubmitButton_Click"
                      runat="server"/>
            </td>
         </tr>

         <tr>
            <td>
               <b>Enter state to query.</b> <br />
               <input id="StateTextBox" 
                      type="Text" 
                      runat="server"/>
               <asp:RequiredFieldValidator ID="StateReqValidator"
                      ControlToValidate="StateTextBox"
                      ErrorMessage="<br />Please enter a state."
                      Display="Dynamic"
                      EnableClientScript="False"
                      runat="server"/>
            </td>
            <td valign="bottom">
               <input id="StateQueryButton"
                      alt="State Submit button"
                      type="Image"
                      src="image.jpg"
                      causesvalidation="False"
                      onserverclick="SubmitButton_Click"
                      runat="server"/>
            </td>
         </tr>

      </table>

      <br /><br />

      <span id="Message"
            runat="Server"/>


   </form>

</body>
</html>

<%@ Page Language="VB" AutoEventWireup="True" %>

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

  Sub SubmitButton_Click(ByVal sender As Object, ByVal e As ImageClickEventArgs)
         
    ' Determine which button was clicked.
    Select Case (CType(sender, HtmlInputImage)).ID

      Case "CityQueryButton"

        ' Validate only the controls used for the city query.
        CityReqValidator.Validate()

        ' Take the appropriate action if the controls pass validation. 
        If CityReqValidator.IsValid Then
           
          Message.InnerHtml = "You have chosen to run a query for the following city: " & _
             CityTextBox.Value
               
        End If

      Case "StateQueryButton"

        ' Validate only the controls used for the state query.
        StateReqValidator.Validate()

        ' Take the appropriate action if the controls pass validation.
        If StateReqValidator.IsValid Then
               
          Message.InnerHtml = "You have chosen to run a query for the following state: " & _
             StateTextBox.Value
               
        End If

      Case Else

        ' If the button clicked isn not recognized, erase the message on the page.
        Message.InnerHtml = ""

    End Select
        
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
<head>
    <title> HtmlInputImage CausesValidation Example </title>
</head>

<body>

   <form id="form1" runat="server">

      <h3> HtmlInputImage CausesValidation Example </h3>

      <table border="1" cellpadding="10">

         <tr>
            <td>
               <b>Enter city to query.</b> <br />
               <input id="CityTextBox" 
                      type="Text"
                      runat="server"/>
               <asp:RequiredFieldValidator ID="CityReqValidator"
                      ControlToValidate="CityTextBox"
                      ErrorMessage="<br />Please enter a city."
                      Display="Dynamic"
                      EnableClientScript="False"
                      runat="server"/>
            </td>
            <td valign="bottom">
               <input id="CityQueryButton"
                      alt="City Submit button"
                      type="Image"
                      src="SubmitImage.jpg"
                      causesvalidation="False"
                      onserverclick="SubmitButton_Click"
                      runat="server"/>
            </td>
         </tr>

         <tr>
            <td>
               <b>Enter state to query.</b> <br />
               <input id="StateTextBox" 
                      type="Text" 
                      runat="server"/>
               <asp:RequiredFieldValidator ID="StateReqValidator"
                      ControlToValidate="StateTextBox"
                      ErrorMessage="<br />Please enter a state."
                      Display="Dynamic"
                      EnableClientScript="False"
                      runat="server"/>
            </td>
            <td valign="bottom">
               <input id="StateQueryButton"
                      alt="State Submit button"
                      type="Image"
                      src="SubmitImage.jpg"
                      causesvalidation="False"
                      onserverclick="SubmitButton_Click"
                      runat="server"/>
            </td>
         </tr>

      </table>

      <br /><br />

      <span id="Message"
            runat="Server"/>


   </form>

</body>
</html>

Remarks

By default, page validation is performed when an HtmlInputImage control is clicked. Page validation determines whether the input controls associated with a validation control on the page all pass the validation rules specified by the validation control.

You can specify or determine whether validation is performed on both the client and the server when an HtmlInputImage control is clicked by using the CausesValidation property. To prevent validation from being performed, set the CausesValidation property to false.

This property is commonly used in the event handler for the ServerClick event to prevent page validation from occurring when a Cancel or Reset button is clicked.

Applies to

See also