Validation occurs after Page_Load, but before event handlers (See http://msdn.microsoft.com/en-us/library/ms178472(v=VS.100).aspx).
If your button does not cause validation, you must manually fire Page.Validate.
You may not interrogate Page.IsValid until after (1) you have called Page.Validate or (2) a control that causes validation was the source of/included in a postback.
If you require validation to occur before event handlers fire, you may use:
if (Page.IsPostback)
{
Page.Validate( /*Control Validation Group Name Optional*/ );
if (Page.IsValid)
{
//Do some cool stuff
}
}
You may also want to consider redesigning so you aren't required to do so.
In an event handler that handles a control which causes validation, Page.IsValid is guaranteed to be available. In all other cases, it is generally safer to re-request validation. One model for handling submissions on a form that has validators:
void btnSubmit_Click(object sender, EventArgs e)
{
this.UpdateGUIWithSubmitRequest();
if (Page.IsValid)
{
this.ProcessSuccessfulSubmission();
}
else
{
this.ProcessInvalidSubmission();
}
}
If you are using a CustomValidator that has a very expensive validation step, you may consider caching the result in the HttpResponse.Cache so you do not have to re-validate if multiple calls to Page.Validate occur.
void CustomValidator_ServerValidate(object source, ServerValidateEventArgs args)
{
CustomValidator self = (CustomValidator)source;
string validatorResultKey = self.ClientID;
bool? validatorResult = Context.Items[validatorResultKey] as bool?;
if (validatorResult.HasValue)
{
args.IsValid = validatorResult.Value;
return;
}
bool isValid = this.DoSomethingVeryTimeConsumingOrExpensive();
Context.Items[validatorResultKey] = isValid;
args.IsValid = isValid;
}
This, of course, depends 100% on your architecture and whether or not you are able to assume that a passed/failed validation during initial validation still passes/fails during subsequent validations of the same Page Life Cycle.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
