Replacing JSubmenuHelper with JHtmlSidebar / Administrative menu in Joomla 4

Question

I've been racking my brain how to add links to all the views of my component in the shiny new Joomla4 backend; I used to do it via JSubmenuHelper, but that, apparently being deprecated also before, has now been completely removed.

I've tried what's mentioned here: How do I apply JHtmlSidebar to add a sidebar to my admin view? , i.e., in the views, I call first the addSubmenu function of the helper (which in turn uses JHtmlSidebar::addEntry), then JHtmlSidebar::render in my view.html.php (in the display method of the JViewLegacy-derived class there).

But I don't get any menu entries for my component. The "default" view shows up fine, but I don't get submenu entries or tabs to link to the other views of my component. There are no errors in the browser or in the logs; I just don't get any indication of the submenu on the left. Edit: I don't get it to run with JHtmlSidebar in J3 as well. There must be something I'm missing. Here's my code: In the view.html.php:

class mycomponentViewblocklist extends JViewLegacy
{
  function display($tpl = null) {
    // other stuff...
    mycomponentHelper::addSubmenu('myview');
    $this->addToolBar();
    $this->sidebar = JHtmlSidebar::render();
    parent::display($tpl);
}

In helpers/mycomponent.php:

class mycomponentHelper extends JHelperContent
{
  public static function addSubmenu($vName)
  {
    JHtmlSidebar::addEntry(
        JText::_('COM_MYCOMPONENT_SUBMENU_MYVIEW'),
        'index.php?option=com_mycomponent&view=myview',
        $vName == 'myview'
    );
    // ...

This does not work in J3 and J4, while using JSubMenuHelper::addEntry instead of JHtmlSidebar::addEntry does work in J3. What else is required? Do I need to add something in my tmpl folder?

I can't see any obvious difference to what I'm doing in comparison to the com_banner component, which gets a nice submenu with all its four views as link entries (edit: see my answer below about the submenu; I misunderstood where that came from; but it also has a nice sidebar on the left in addition to the submenu).

For all the announcement of Joomla4, so far I have seen relatively little in terms of migration guides for J3 / J2 components, could anybody point me in some direction there maybe, if this could help the issue here?

Answer 1

Finally figured it out - my problem is a missing placeholder in the tmpl (which was not required for JSubMenuHelper). Added this to my tmpl/default.php, now it works:

<div id="j-sidebar-container" class="span2">
    <?php echo $this->sidebar; ?>
</div>

The submenu in banners I was wondering about is actually done via the manifest file, there are entries like this:

<administration>
  <menu img="class:banners">com_banners</menu>
  <submenu>
    <!--
      Note that all & must be escaped to &amp; for the file to be valid
      XML and be parsed by the installer
    -->
    <menu
      link="option=com_banners"
      view="banners"
      img="class:banners"
      alt="Banners/Banners"
      >
      com_banners_banners
    </menu>
    <menu
      link="option=com_categories&amp;extension=com_banners"
      view="categories"
      img="class:banners-cat"
      alt="Banners/Categories"
      >
      com_banners_categories
    </menu>
    ...

These are responsible for creating the submenu both in J3 and J4.