LiveView Uploads: resuming on cancel with auto_upload

I’m currently implementing the brand new LiveView Uploads, using the auto_upload setting, and I have a situation which I’m not sure how to resolve.

The uploader is configured to handle multiple images, with auto_upload: true:

|> allow_upload(:images,
  accept: [".jpg", ".jpeg", ".png"],
  auto_upload: true,
  progress: &handle_progress/3,
  max_file_size: 5 * 1024 * 1024,
  max_entries: 20

The actual file upoad input is hidden, so we have drag and drop only.

When you drop a bunch a files, and they are all valid, the upload starts and everything works as expected. However, if there is a single file that’s invalid, the whole batch of files stops. I have implemented a cancel button so you can cancel individual files from the UI:

  def handle_event("cancel-upload", %{"ref" => ref}, socket) do
    {:noreply, cancel_upload(socket, :images, ref)}

The problem I’m facing is that after I cancel the invalid file(s), the remaining valid files does not resume uploading. Unless I submit the form or add drag and drop more files, nothing will get uploaded.

I’m looking for a way to “retry” uploading files or trigger auto_upload again, if all entries on the uploader are valid. Does anyone have any ideas how to do it?

Here is my template markup (simplified version) just for completeness:

<%= live_file_input @uploads.images, class: "is-hidden" %>

<div class="dropzone" phx-hook="DragOver" phx-drop-target="<%= @uploads.images.ref %>">
  Drag and drop your files here

<table class="uploads-in-progress table">
    <%= for entry <- @uploads.images.entries do %>
        <td class="<%= if !entry.valid?, do: "has-text-danger" %>"><%= entry.client_name %></td>
        <td><progress class="progress" value="<%= entry.progress %>" max="100"><%= entry.progress %></progress></td>
        <td class="has-text-danger"><span class="is-clickable" phx-click="cancel-upload" phx-value-ref="<%= entry.ref %>">Cancel</span></td>
    <% end %>

I have a workaround, which is a bit of a hack… Here it is for anyone interested:

I noticed that live_view.js simply dispatches an input event to the drop target here so I created a hook that triggers the event:

Hooks.ResumeUpload = {
  mounted() {
    this.handleEvent('resume_upload', ({id}) => {
      const dropTarget = document.getElementById(id);
      dropTarget.dispatchEvent(new Event('input', { bubbles: true }));

The hook subscribes to a resume_upload event, which is triggered when you cancel an upload:

def handle_event("cancel_upload", %{"ref" => ref}, socket) do
  socket =
    |> cancel_upload(:images, ref)
    |> push_event("resume_upload", %{id: socket.assigns.uploads.images.ref})

  {:noreply, socket}

and in the template I just had to find a place for the hook:

<div id="upload-section" phx-hook="ResumeUpload">
  <!-- same code as before ... -->

I wonder if there is a better way to accomplish this :thinking:


Thanks for sharing the solution.

Hi guys,

We are facing the similar issue and I wonder what exactly is going on here and if this is how uploads should be unstuck?

We would like to keep failed uploads in the list and ideally they shouldn’t affect other uploads at all.