personal-book/app/views/admin/books/index.html.erb

<script src="https://kit.fontawesome.com/1fa49cfdc9.js" crossorigin="anonymous"></script>
<script>
function MergeUrl(){
  var temp_url = location.href
  if (temp_url.search("locale=")!=-1){
    var tp=temp_url.lastIndexOf('/')
    location.href = temp_url.substring(0,tp+1)+"merge/"+temp_url.substring(tp+1)
  }
  else if (temp_url.slice(-1)=='/'){
    location.href = location.href + "merge"
  }
  else{
    location.href = location.href + "/merge"
  }
}
</script>
<table class="table main-list">
	<thead>
		<tr>
			<th class="span1"><%= t("personal_book.year") %></th>
			<th class="span7"><%= t("personal_book.book_title") %></th>
			<th class="span1"><%= t("personal_plugins.author") %></th>
		</tr>
	</thead>
	<tbody id="tbody_writing_books" class="sort-holder">
		<%= render 'writing_book' %>
	</tbody>
</table>

<div class="bottomnav clearfix">
	<div class="action pull-right">
	  <div class="dropup upload-button">
        <button class="btn btn-primary" type="button" onclick="MergeUrl()">
          <i class="far fa-object-group"></i>
          <span class="group"></span><%= t('personal_book.merge') %>
        </button>
        <button class="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">
          <i class="icon-upload-alt icon-white"></i><%= t('personal_book.upload') %>
          <span class="caret"></span>
        </button>
        <div class="dropdown-menu upload-box">
          <form action="/admin/books/import_from_excel" method="post" enctype="multipart/form-data">
            <%= hidden_field_tag :authenticity_token, form_authenticity_token %>
            <input type="file" name="import_file" >
              <button class="btn btn-primary" type="submit"><%= t(:submit) %></button>
              <a class="" href="/admin/books/download_excel_format.xlsx">Download excel format</a>
          </form>
        </div>
      </div>
		<%= link_to content_tag(:i, nil, :class => 'icon-plus icon-white') + t(:new_), new_admin_book_path, :class => 'btn btn-primary' %>
		<% if current_user.is_admin? %>
			<%= link_to content_tag(:i, nil, :class => 'icon-cog icon-white') + t('setting'), admin_book_setting_path, :class => 'btn btn-primary pull-right' %>
		<% end %>
	</div>
	<div class="pagination pagination-centered">
    <%= content_tag :div, paginate(@writing_books), class: "pagination pagination-centered" %>
  </div>
</div>
<% if params[:error] == "1" %>
  <script type="text/javascript">
    alert("File cannot be imported. File has more than 500 entries. Please seperate the entries in different files.");
    window.location.href = "<%= admin_books_url %>"
  </script>
<% end %>