Phoenix File Uploads

allow_upload(:upload_name,
  accept: ~w(.jpg .jpeg .png .pdf),
  max_entries: 10,
  max_file_size: 10_000_000
)

@impl true
def mount(_params, _session, socket) do
  socket =
    socket
    |> assign(:uploaded_files, [])
    |> allow_upload(:photos,
         accept: ~w(.jpg .jpeg .png),
         max_entries: 5,
         max_file_size: 10_000_000
       )

  {:ok, socket}
end

@impl true
def handle_event("validate", _params, socket) do
  {:noreply, socket}
end

@impl true
def handle_event("save", _params, socket) do
  uploaded_files =
    consume_uploaded_entries(socket, :photos, fn %{path: path}, entry ->
      dest = Path.join(["priv", "static", "uploads", safe_filename(entry.client_name)])
      File.mkdir_p!(Path.dirname(dest))
      File.cp!(path, dest)
      {:ok, ~s(/uploads/#{Path.basename(dest)})}
    end)

  {:noreply, assign(socket, :uploaded_files, uploaded_files)}
end

defp safe_filename(original_name) do
  ext = Path.extname(original_name)
  "#{Ecto.UUID.generate()}#{ext}"
end

<.form for={%{}} phx-submit="save" phx-change="validate" id="upload-form">
  <div phx-drop-target={@uploads.photos.ref}>
    <.live_file_input upload={@uploads.photos} />
  </div>

  <%= for entry <- @uploads.photos.entries do %>
    <div>
      <.live_img_preview entry={entry} />
      <progress value={entry.progress} max="100"><%= entry.progress %>%</progress>

      <%= for err <- upload_errors(@uploads.photos, entry) do %>
        <p class="error"><%= error_to_string(err) %></p>
      <% end %>
    </div>
  <% end %>

  <button type="submit">Upload</button>
</.form>

def error_to_string(:too_large), do: "Too large"
def error_to_string(:too_many_files), do: "Too many files"
def error_to_string(:not_accepted), do: "Unacceptable file type"

# lib/my_app_web endpoint.ex
def static_paths do
  ~w(assets fonts images favicon.ico robots.txt uploads)
end