Enable/disable RequiredValidator on client-side / CustomValidator not firing

Question

I've got a drop-down where the user selects a Country. It is a required "field".

Next to it, there is a textfield named State. If the user selects US, then the field State is required. If the user selects e.g. Sweden, the State is not required, since Sweden has no states.

Example code:

<asp:DropDownList runat="server" ID="Country"></asp:DropDownList>
<asp:RequiredFieldValidator ControlToValidate="Country"
                runat="server" Display="Static" ErrorMessage="Required field" />

<asp:TextBox runat="server" ID="State"></asp:TextBox>
<asp:CustomValidator ClientValidationFunction="DoesntGetFiredIfStateIsEmpty"
                runat="server" Display="Static" ErrorMessage="Required field" />

<!-- SO, RATHER THIS TOGETHER WITH CONDITIONAL FIRING -->
<asp:RequiredFieldValidator ControlToValidate="State"
                runat="server" Display="Static" ErrorMessage="Required field" />

My question to you is: How can I make this CustomValidator fire validation when it is empty?

Or put simplier: How can I make a RequiredValidator fire conditionally?

Or simplest: How can I enable/disable a RequiredValidator on client-side?

Alkylation

Answer 1

Try doing this with javascript to enable and disable validators

ValidatorEnable(RequiredFieldValidatorId, false);

Check out this question that I answered.

Amygdala

Looked hopeful, but I get "val.style is undefined" in the ASP.NET generated JS... – Alkylation

I got it working. The validator had a parent with display: none; set on it, which broke the functionality of ValidatorEnable. – Alkylation

The first parameter is actually supposed to be the validator itself, not the validator's ID. – Shuck

@itison - #2555340 – Amygdala

@Amygdala I saw that, but I think it's still worth pointing out here. Your snippet involves passing in "RequiredFieldValidatorId", which I think is a bit misleading when it's not supposed to be an ID. – Shuck

Answer 2

Asp.net has a client side javascript function to manage the validators, the "ValidatorEnable" function,

ValidatorEnable(RequiredFieldValidatorId, false);

you can call it simply using javascript, you must send the validator object to the function (not only its id).

if (x==y) {
        ValidatorEnable($('#<%=rfvFamily.ClientID %>'), false);    
    } else {
        ValidatorEnable($('#<%=rfvFamily.ClientID %>'), true);
    }

or

if (x==y) {
        ValidatorEnable(document.getElementById("<%=rfvFamily.ClientID %>", false);    
    } else {
        ValidatorEnable(document.getElementById("<%=rfvFamily.ClientID %>", true);
    }

full documnet on: http://msdn.microsoft.com/en-us/library/Aa479045#aspplusvalid_clientside

another way is to Set in your DropDownList CausesValidation="false" to avoid that the validators block a postback when you change the DropDownList entry.

(*) Remember this function is for client side, for disabling validator in server side, you must to disable validator on page postback too.

if (IsPostBack){
    if (x==y) {
        rfvFamily.Enabled = false;
    }
}

Snip

You need to pass in the element, not the id. – Gwin