注册到剃须刀@ Html.HiddenFor的onchange事件

Question

I am using asp.net mvc 4, jquery and razor. I have below razor statemet in my view:

@Html.HiddenFor(m => m.MyItemViewModel.id);

I need to call a jquery/javascript function when its value changes. So I have thought to suscribe jquery/javascript function to onchange event for HiddenFor razor tag but I do not know if it is possible.

I have implemented below code but it seems to not work as OnHiddenValueChanged is not reached:

@Html.HiddenFor(m => m.ItemCompViewModel.id, new { onchange="OnHiddenValueChanged" });

<script>
    function OnHiddenValueChanged() {
    }
</script>

Or even better, how to detect from view when m.ItemCompViewModel.id (the item for my view model) has changed and then call the jquery/javascript function?

Any ideas?

Answer 1

It looks like you are attempting to subscribe to the onchange client side function for a value that is generated on the server and changes only on the server. So it's normal that this client side function is never triggered. Actually you never used any javascript to change the value of the hidden field so you cannot expect this callback to be raised.

If you are modifying the value on the server, then it's up to the server to tell the client that the value changed. For example you could have some additional property on your view model telling that the value has changed (whatever that means in your context - because changed .must always be compared to some previous state). Then on the client you could serialize this property as a javascript variable so that the client side knows about the change that occured on the server.