Creating Custom Pages

In this chapter, we will make custom pages with controllers. A controller is a class that contains a method used to build a page when Drupal is accessed at a specific path. Creating custom pages allows you to extend Drupal beyond just the content pages. This chapter will cover the process of creating custom pages, receiving dynamic values from paths, and serving JSON or file download responses.

In this chapter, we will learn about the following recipes:

• Defining a controller to provide a custom page
• Using route parameters
• Creating a dynamic redirect page
• Creating a JSON response
• Serving files for download

Technical requirements

This chapter requires an existing custom module installed on your Drupal site. This custom module will contain the controllers created throughout this recipe. Chapter 4, Extending Drupal with Custom Code, covers how to create a custom module. You can find the full code used in this chapter on GitHub: https://github.com/PacktPublishing/Drupal-10-Development-Cookbook/tree/main/chp05

Defining a controller to provide a custom page

Whenever an HTTP request is made to a Drupal site, the path for the URL is routed to a controller. Controllers are responsible for returning the response for a path that has been defined as a route. Generally, these controllers return render arrays for Drupal’s render system to convert into HTML.

In this recipe, we will define a controller that returns a render array to display a message on the page.

How to do it…

1. First, we need to create the src/Controller directory in the module’s directory. We will put our controller class in this directory, which gives our controller class the Controller namespace:

   mkdir -p src/Controller

2. Create a file named HelloWorldController.php in the controller directory. This will hold our HelloWorldController controller class.
3. Our HelloWorldController class will extend the ControllerBase base class provided by Drupal core:

   <?php

   namespace Drupal\mymodule\Controller...

Using route parameters

In the previous recipe, we defined a route and controller that responded to the /hello-world path. A route can add variables to the path, called route parameters, so that the controller can handle different URLs.

In this recipe, we will create a route that takes a user ID as a route parameter to display information about that user.

Getting started

This recipe uses the route created in the Defining a controller recipe to provide a custom page.

How to do it…

1. First, remove the src/Routing/RouteSubscriber.php file and mymodule.services.yml from the previous section and clear the Drupal cache, so it does not interfere with what we are about to do.
2. Next, edit routing.yml so that we can add a route parameter of user to the path:

     path: /hello-world/{user}

Route parameters are wrapped with an opening bracket ({) and a closing bracket (}).

3. Next, we will update the requirements key to specify that the user parameter...

Creating a dynamic redirect page

Controllers for routes in Drupal can return request objects provided by the Symfony HttpFoundation component instead of a render array. When a response object is returned, the render system is bypassed and the response object is handled directly.

In this recipe, we will create a route that redirects authenticated users to the homepage and anonymous users to the user login form.

How to do it…

1. First, we need to create the src/Controller directory in the module’s directory. We will put our controller class in this directory, which gives our controller class the Controller namespace:

   mkdir -p src/Controller

2. Create a file named RedirectController.php in the Controller directory. This will hold our RedirectController controller class.
3. Our RedirectController class will extend the ControllerBase base class provided by Drupal core:

   <?php

   namespace Drupal\mymodule\Controller;

   use Drupal\Core\Controller\ControllerBase;

   class RedirectController...

Creating a JSON response

Routes can also return JavaScript Object Notation (JSON) responses. A JSON response is often used for building API routes since it is an interchange format that is supported by all programming languages. This allows exposing data to be consumed by a third-party consumer.

In this recipe, we will create a route that returns a JSON response containing information about the Drupal site.

How to do it…

1. First, we need to create the src/Controller directory in the module’s directory. We will put our controller class in this directory, which gives our controller class the Controller namespace:

   mkdir -p src/Controller

2. Create a file named SiteInfoController.php in the Controller directory. This will hold our SiteInfoController controller class.
3. Our SiteInfoController class will extend the ControllerBase base class provided by Drupal core:

   <?php

   namespace Drupal\mymodule\Controller;

   use Drupal\Core\Controller\ControllerBase;

   use Symfony...

Serving files for download

Routes can be used to serve file downloads with the BinaryFileResponse response object. Using the BinaryFileResponse to serve a file for download allows you to keep the original file’s URL private or to send dynamic content as a file download.

In this recipe, we will create a route that provides a download for a PDF.

Getting started

This recipe uses a PDF file that is located in the same directory as the module. You can use any other available file type, such as a text file. A test PDF can be found on the World Wide Web Consortium website at https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf.

How to do it…

1. First, we need to create the src/Controller directory in the module’s directory. We will put our controller class in this directory, which gives our controller class the Controller namespace:

   mkdir -p src/Controller

2. Create a file named DownloadController.php in the Controller directory. This...