ASP .NET - How to use ASP.NET validators

Author

How to use ASP.NET validators

Madhur

2008-04-17, 7:35 pm

Hello All

I am learning how to use ASP.NET Validators and would appreciate if someone
could provide me with guidance.

I have written very simple ASPX page below with a Dropdown list, a button.
If a value of 3 is selected inside dropdown list , I add two text boxes each
attached with validators.

Although validators work and do show th error messages in Red if the range
is outside 10, the call to the function Page.IsValid always returns TRUE
inside my button event handler. It should return false, since the validation
has false, isn't it?

using System;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

public partial class _Default : System.Web.UI.Page
{
TextBox txtbox;
protected void Page_PreInit(object sender, EventArgs e)
{
DropDownList1.AutoPostBack = true;
}

protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
DropDownList1.Items.Add("1");
DropDownList1.Items.Add("2");
DropDownList1.Items.Add("3");

}
else
{
AddControls();

}
}
protected void Button1_Click(object sender, EventArgs e)
{
System.Text.StringBuilder displayValues = new
System.Text.StringBuilder();
if (Page.IsValid)
{
int i = 10; //this event always fires
}
Page.Validate();

}
protected void DropDownList1_SelectedIndexChanged(objec
t sender,
EventArgs e)
{

// AddControls();

}

private void AddControls()
{
if (DropDownList1.SelectedIndex == 2)
{
RangeValidator rv;

for (int i = 0; i < 2; ++i)
{
txtbox = new TextBox();
txtbox.ID = "madhur" + i.ToString();
txtbox.ValidationGroup = "madhur";

rv = new RangeValidator();
rv.ID = "validator" + i.ToString();
rv.EnableClientScript = false;
rv.Text = "*";
rv.MinimumValue = "10";
rv.MaximumValue = "10";
rv.EnableClientScript = true;
rv.ErrorMessage = "this is an error";
rv.Display = ValidatorDisplay.Dynamic;
rv.ControlToValidate = "madhur" + i.ToString();
rv.Type = ValidationDataType.Integer;
rv.Enabled = true;
rv.ValidationGroup = "madhur";
rv.SetFocusOnError = true;

this.form1.Controls.Add(txtbox);
this.form1.Controls.Add(rv);

}
}
}
}

Thanks,
Madhur

wisccal@googlemail.com

2008-04-18, 5:06 am

Hi Madhur,

Try setting the ValidatorGroup Property on Button1 instead of textbox.
From the ASP.Net doc at http://msdn2.microsoft.com/en-us/li...validator.aspx:

"These controls each have a ValidationGroup property that, when set,
validates only the validation controls within the specified group when
the control triggers a post back to the server."

The key part being "...when the control triggers a post back to the
server." So, you need to set the ValidatorGroup Property on the
control that posts back to the server. You already associated the
control that has to be checked with its Validator by setting
rv.ControlToValidate.

Of course, you can also call the Page.Validate() method to trigger
validation in the codebehind. But then, you need to do it before you
check Page.IsValid. In your Button1_Click event, you do it the other
way around.

===========
Regards,
Steve
www.stkomp.com

Madhur wrote:
> Hello All
>
> I am learning how to use ASP.NET Validators and would appreciate if someone
> could provide me with guidance.
>
> I have written very simple ASPX page below with a Dropdown list, a button.
> If a value of 3 is selected inside dropdown list , I add two text boxes each
> attached with validators.
>
>
> Although validators work and do show th error messages in Red if the range
> is outside 10, the call to the function Page.IsValid always returns TRUE
> inside my button event handler. It should return false, since the validation
> has false, isn't it?
>
>
> using System;
> using System.Configuration;
> using System.Data;
> using System.Web;
> using System.Web.Security;
> using System.Web.UI;
> using System.Web.UI.HtmlControls;
> using System.Web.UI.WebControls;
> using System.Web.UI.WebControls.WebParts;
>
> public partial class _Default : System.Web.UI.Page
> {
> TextBox txtbox;
> protected void Page_PreInit(object sender, EventArgs e)
> {
> DropDownList1.AutoPostBack = true;
> }
>
> protected void Page_Load(object sender, EventArgs e)
> {
> if (!Page.IsPostBack)
> {
> DropDownList1.Items.Add("1");
> DropDownList1.Items.Add("2");
> DropDownList1.Items.Add("3");
>
>
> }
> else
> {
> AddControls();
>
> }
> }
> protected void Button1_Click(object sender, EventArgs e)
> {
> System.Text.StringBuilder displayValues = new
> System.Text.StringBuilder();
> if (Page.IsValid)
> {
> int i = 10; //this event always fires
> }
> Page.Validate();
>
> }
> protected void DropDownList1_SelectedIndexChanged(objec
t sender,
> EventArgs e)
> {
>
> // AddControls();
>
> }
>
> private void AddControls()
> {
> if (DropDownList1.SelectedIndex == 2)
> {
> RangeValidator rv;
>
> for (int i = 0; i < 2; ++i)
> {
> txtbox = new TextBox();
> txtbox.ID = "madhur" + i.ToString();
> txtbox.ValidationGroup = "madhur";
>
> rv = new RangeValidator();
> rv.ID = "validator" + i.ToString();
> rv.EnableClientScript = false;
> rv.Text = "*";
> rv.MinimumValue = "10";
> rv.MaximumValue = "10";
> rv.EnableClientScript = true;
> rv.ErrorMessage = "this is an error";
> rv.Display = ValidatorDisplay.Dynamic;
> rv.ControlToValidate = "madhur" + i.ToString();
> rv.Type = ValidationDataType.Integer;
> rv.Enabled = true;
> rv.ValidationGroup = "madhur";
> rv.SetFocusOnError = true;
>
> this.form1.Controls.Add(txtbox);
> this.form1.Controls.Add(rv);
>
>
>
> }
> }
> }
> }
>
> Thanks,
> Madhur

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