Hello Acadia,
I suggest you using the
OnClientFileSelected event which the RadUpload control provides and set a javascript function for an event handler to implement your custom logic. Please, refer to
this help article for more details about this client-side event and a sample code-snippet demonstrating its use.
Regarding the other question about detecting whether a file has actually been selected, you can check the value of the file input field via javascript - use the
get_fileInputField to get the input field of the selected file which the eventArgs of the
OnClientFileSelected provide. However, if you want to avoid someone type a path in the file input field instead of using the Browse dialog for selecting a file you can set the
ReadOnlyFileInputs property of the RadUpload control to
true.
Kind regards,
Sophy
the Telerik team