How to add an existing path in your custom module to Drupal Menu system

Here we are going to discuss how to show custom routes created in custom module in Drupal menu system.

Go to Structure-> Menu under path admin/structure/menu

You can see below menu links,

All menu links goes under these menus, here we are going to assign our custom  module link to Main navigation 

While click edit of any of Main Navigation you can see below URL in address bar.

/admin/structure/menu/manage/main

Here in last part of path you can see main, this will use as menu name in coming section.

So here we have a student form in our custom module  dn_menu

We have student form in path /src/Form/StudentForm.php

We have below entry in dn_menu.routing.yml.

dn_menu.add_menu:
  path: '/menu/students/add'
  defaults:
    _title: 'Add Students Menu'
    _form: '\Drupal\dn_menu\Form\StudentForm'
  requirements:
    _access: 'TRUE'

So in order to load to this form as a link in Main Menu, we are creating file  dn_menu.links.menu.yml   in our custom module root path with below content.

dn_menu.students:
  title: 'Student Form Menu'
  description: 'link student entiries'
  parent: main
  menu_name: main
  route_name: dn_menu.add_menu

Parent is optional and menu name is the name of Menu navigation that we took from edit url of Main navigation menu.

Clear the cache, under Main Navigation, you can see Student Form Menu, which is the title of our custom menu. Link of this Menu is the path mentioned in routing.yml.

Click on edit on this menu, you can see like path and title cannot be edited.

You are free to change the parent link, also other options  are editable.

Download sample dn_menu module here