ASP.Net Server Side Custom Validator control help needed

Question

I have a page with a textbox control, a Custom Validator, a button to save entered data and code to handle the custom validation.

I set up a simple code test just to see how the Custom Validators work. I hope to add more validations that check multiple controls later. The same thing happens if I do add the ControlToValidate attribute for the textbox control. (I don't think I need a "ControlToValidate" attribute for this. I plan to validate multiple controls later. I can't put all the controls I am validating in that attribute.)

When I run my app, the save takes place and the validation is happeing - the message appears. I don't understand why the save isn't stopped when I enter "3" in the textbox I am checking. If the validation is happening, and if the IsValid = false, why is the save taking place?

Here is the Custom Validator:

<asp:CustomValidator ID="VisitSaveCustomValidator" runat="server" OnServerValidate="VisitSaveCustomValidator_ServerValidate" ValidationGroup="SaveVisit_val"></asp:CustomValidator>

Here is the button:

<asp:Button ID="SaveVisit_btn" runat="server" Visible="false" Text="- Save Visit -" ValidationGroup="SaveVisit_val" OnClick="SaveVisit_btn_Click" />

Here is the code for the Custom Validator:

protected void VisitSaveCustomValidator_ServerValidate(object source, ServerValidateEventArgs args)
{
    if (VisitNumber_tbx.Text == "3")
    {
        args.IsValid = false;
        VisitSaveCustomValidator.ErrorMessage = "The Visit Number cannot be 3.";
    }
    else
    {
        args.IsValid = true;

    }

Please let me know if I need to add more code or more information. I thought this would be pretty straight-forward. I followed an example in a book and some online. I understand that the page is going back to the server to be validated. But, shouldn't the save be stopped since the IsValid = false?

It seems like the save is happening first, then the validation code executes, which causes the message to appear.

Thanks.

As @Smeegs points out in his answer you will need to explicitly call the .Validate method because you haven't set up a "control to validate" - otherwise this would normally be handled in the "Page.IsValid" process. I'm not sure what real benefit you're getting using a custom validator that is specifically bound to form as yours is - you should really attach it to at least one field so that you can hook into the other features (like highlighting fields, etc.). — Zhaph - Ben Duguid
I did this test because I want to eventually add a validation that checks to see if at least one of four checkboxes are checked. So, I can't include all four in the Control To Validate. — Junco
Thank you for looking at my question and giving some feedback, Ben. — Junco
True, I've had similar requirements in the past if you take a look at the Compare Validator you can see how multiple controls can be referenced through additional properties. I would still attach the validator to a control (perhaps the most common option), then pass in the ids of the other controls as a list - this way you'll be able to focus the user in the right area and position it so the error is shown with the group. — Zhaph - Ben Duguid

Smeegs Smeegs · Accepted Answer · 2014-06-20T15:42:53

I believe you may have to manually call the validate method.

VisitSaveCustomValidator.Validate();

Then check to see if it was valid.

VisitSaveCustomValidator.IsValid();

This can be put in the button click event.

ASP.Net Server Side Custom Validator control help needed

1 Answers