Reject Data on @OnChange event on a textbox.

[b-giavotto]

Is there an existing issue for this?

• [X] I have searched the existing issues

Describe the bug

BlazorServer: apparently there is no way to reject changes to an input box in a onchange event.

Expected Behavior

Steps to reproduce the problem: place an input box, and bind it's value property to a page property called string inputvalue. also bind an onchange event to an eventhandler called checkvalue. Add some code to reject an invalid value and some other to accept the value like this:

public void checkvalue(ChangeEventArgs args)
{
// if the value is OK we update the inputvalue property that is bould to a value attribute of input otherwise not.

if (isvalid)
{
inputvalue = .....
}

}

Steps To Reproduce

enter an invalid value, by violating the rule applyed on server. in the input. the value should be reverted back as you focus to another control. however this does not happen.

That is because, we are keeping the old value server side so the diffing algo does not apply any change to the input box. Actually the only workaround is to invoke a javascript function that force the textbox value to the old value.

Is there a way a more elegant solution?

Thx Best regards.

Exceptions (if any)

none

.NET Version

does not apply

Anything else?

.

[ghost]

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