Remove component's view name from url joomla 4

Question

I am using Joomla 4.2.1. I installed custom component which is previously used into Joomla 3.10.11.

I create a menu item with view from this component.

On Joomla 3.10.11 it works fine

for example : http://mylocal.local/index.php/kurse-nach-datum

But

on Joomla 4.2.1 it create url with view name

For example : http://mylocal.local/index.php/kurse-nach-datum/courses

kurse-nach-datum is the Alias of link

and link is index.php?option=com_course&view=courses

Router.php

<?php

/**
 * @version     3.4.0
 * @package     com_course
 * @copyright   Copyright (C) 2015. All rights reserved.
 * @license
 * @author      -
 */
// No direct access
defined('_JEXEC') or die;

/**
 * @param   array   A named array
 * @return  array
 */
function CourseBuildRoute(&$query) {
    $segments = array();

    if (isset($query['task'])) {
        $segments[] = implode('/', explode('.', $query['task']));
        unset($query['task']);
    }
    if (isset($query['view'])) {
        $segments[] = $query['view'];
        unset($query['view']);
    }
    if (isset($query['id'])) {
        $segments[] = $query['id'];
        unset($query['id']);
    }

    return $segments;
}

/**
 * @param   array   A named array
 * @param   array
 *
 * Formats:
 *
 * index.php?/course/task/id/Itemid
 *
 * index.php?/course/id/Itemid
 */
function CourseParseRoute($segments) {
    $vars = array();
    // view is always the first element of the array
    $vars['view'] = array_shift($segments);

    while(!empty($segments)) {

        $segment = array_pop($segments);
        if (is_numeric($segment)) {
            $vars['id'] = $segment;
        } else {
            $vars['task'] = $vars['view'] . '.' . $segment;
        }
    }

    return $vars;
}

Answer 1

There have been many changes in routing in J4. One in particular is that URLs containing only menu item ID (e.g. index.php?Itemid=145) now have all menu query parameters appended before being passed to component router. In J3, only component was added. This is an issue for you because your router unconditionally appends the view to the path:

if (isset($query['view'])) {
    $segments[] = $query['view'];
    unset($query['view']);
}

This isn't entirely correct even for J3, since building the link with correct item ID:

index.php?option=com_courses&view=course&Itemid=145

results in URL containing the view after menu alias:

index.php/[menu-alias]/course

To solve the issue you essentially need to add logic to handle URLs with and without menu item IDs. So that the view is added to the path only when needed. Instead of writing this code yourself, you could convert your old router to a rule-based router, i.e. by extending Joomla\CMS\Component\Router\RouterView. The included core rules should already handle this.

Also, in case you're getting 404 errors in your component, it's probably because your parse function has incorrect function signature. $segments argument should be passed by reference because the modification made to it matter.

function CourseParseRoute(&$segments) {