Just wondering if it is possible to override the multi upload button so that before uploading the files it validates some other settings?
e.g. the files will be uploaded with a filetype descriptor which must be selected before trying to upload them.
You need to override it anyway to add files to yours permanent storage. Just clear uploads if file type is null or whatever condition you want.
But other solution can be found. You can just not bait user with multiUpload button and set it enabled=false. And enable it in filetypes field listener.
Was probably a silly question, but thank you.
For simple restriction on file extensions you can use the
permittedExtensions XML attribute (and the corresponding
setPermittedExtensions() method) sets the white list of permitted file extensions. The value of the attribute should be a set of string values, where each string is a permitted extension with leading dot. For example: