examples-3.x-dev/modules/page_example/page_example.routing.yml

# In order to to create pages it is necessary to define routes for them. A route
# maps a URL path to a controller. It defines with what function or method will
# be called when a URL is accessed. The following lines defines three of them
# for this module.
# Menu items corresponding to these URLs are defined separately in the
# page_example.links.menu.yml file.
# If the user accesses http://example.com/?q=examples/page-example, the routing
# system will look for a route with that path. In this case it will find a
# match, and execute the _controller callback. In this case the callback is
# defined as a classname
# ("\Drupal\page_example\Controller\PageExampleController") and a method
# ("description").

# Access to this path is not restricted. This is notated as _access: 'TRUE'.
page_example.description:
  path: '/examples/page-example'
  defaults:
    _controller: '\Drupal\page_example\Controller\PageExampleController::description'
    _title: 'Page Example'
  requirements:
    _permission: 'access content'

# If the user accesses http://example.com/?q=examples/page-example/simple,
# the routing system will look for a route with that path. In this case it will
# find a match, and execute the _controller callback. Access to this path
# requires "access simple page" permission.
page_example.simple:
  path: '/examples/page-example/simple'
  defaults:
    _controller: '\Drupal\page_example\Controller\PageExampleController::simple'
    _title: 'Simple - no arguments'
  requirements:
    _permission: 'access simple page'

# If the user accesses
# http://example.com/?q=examples/page-example/arguments/1/2, the routing system
# will first look for examples/page-example/arguments/1/2. Not finding a match,
# it will look for examples/page-example/arguments/1/{*}. Again not finding a
# match, it will look for examples/page-example/arguments/{*}/2. Yet again not
# finding a match, it will look for examples/page-example/arguments/{*}/{*}.
# This time it finds a match, and so it will execute the _controller callback.
# In this case, it's PageExampleController::arguments().
# Since the parameters are passed to the function after the match, the function
# can do additional checking or make use of them before executing the callback
# function. The placeholder names "first" and "second" are arbitrary but must
# match the variable names in the callback method, e.g. "$first" and "$second".
page_example.arguments:
  path: '/examples/page-example/arguments/{first}/{second}'
  defaults:
    _controller: '\Drupal\page_example\Controller\PageExampleController::arguments'
  requirements:
    _permission: 'access arguments page'