Wasm-bindgen: Converting a File or Blob into a byte slice &[u8]

[chinedufn]

I'm tryin to implement drag and drop and I'd like to go get the byte slice for the file that is uploaded.

I can easily get a File or Blob, but I'm unsure about how to convert them into a byte slice.

Is there a way to do that right now?

Thanks!!

[chinedufn]

Hmm this is a classic case of jumping to wasm-bindgen instead of doing some thinking...

Did a quick google and it turns out that you can convert a blob into a typed array using a FileReader.

I'll give that a stab https://rustwasm.github.io/wasm-bindgen/api/web_sys/struct.FileReaderSync.html

[chinedufn]

Just in case anyone else comes here because they're searching about file uploads....

My use case ended up looking like this:

html! {
<div
    ondrop=move |event: web_sys::DragEvent| {
       event.prevent_default();
       event.stop_propagation();

       let store = Rc::clone(&store_clone);

       let dt = event.data_transfer().unwrap();
       let files = dt.files().unwrap();
       let psd = files.item(0).unwrap();

       let file_reader = web_sys::FileReader::new().unwrap();
       file_reader.read_as_array_buffer(&psd).unwrap();

       let mut onload = Closure::wrap(Box::new(move |event: Event| {
           let file_reader: FileReader = event.target().unwrap().dyn_into().unwrap();
           let psd = file_reader.result().unwrap();
           let psd = js_sys::Uint8Array::new(&psd);

           let mut psd_file = vec![0; psd.length() as usize];
           psd.copy_to(&mut psd_file);

           store.borrow_mut().msg(&Msg::ReplacePsd(&psd_file));
       }) as Box<FnMut(_)>);

       file_reader.set_onload(Some(onload.as_ref().unchecked_ref()));
       onload.forget();
    }
>
</div>
}

Hope it helps!