Related to the previous tutorial where we implemented best practices to centralize our configuration, we also want to minimize the number of database connections. We want one connection that every class uses. In this tutorial we'll move the new PDO()
call out of ShipLoader
so that it can be created in a central location and used by everyone. How? By using the same strategy we just learned with configuration. If you want to move something out of a service class, add it as a __construct()
argument and pass it in.
So far we have to create our service objects by hand and this stuff is duplicated. We need to centralize our service objects to make our lives easier. To do that, in this tutorial we'll create one special class whose only job is to create these service objects. This class is called a service container because, well, it's basically a container for all the service objects. We're going to create our service container and then update our code to use it properly.
To wrap things up with our app, the last bit of housekeeping is to make one container responsible for creating every service object, like PDO, but also ShipLoader
and BattleManager
. The problem is that if we called $container->getPDO()
twice on the same request, we'd still end up with multiple PDO
objects, and so, multiple database connections. Ok, if we're careful, we can avoid this. We can do better though—let's guarantee that only one PDO
object is ever created. We did this previously in ShipLoader
, so now we'll move this into our container.
We've got a nice little app working now, using our service container well. Good work! In this final lesson for this series we're going to have a review of working with containers. We'll look at why this is such a good practice, discuss model classes versus service classes, and take a moment to acknowledge best practices versus the real world implementations you can end up with.
Additional resources
In this series, we’ll continue to build the spaceship app that we’ve started in Introduction to Object-Oriented PHP and Object-Oriented PHP Part 2. In this tutorial, I’ll show you how to use the extends
keyword in PHP so that you can use it to inherit properties and methods from another class
.
Additional resources
In this tutorial, I will show you how to override a method that you’ve inherited from another class. By having two classes we are starting to shape the different behaviors and properties of each, while still keeping most things in common and not duplicated.
In this tutorial, I will show you the difference between public, private, and protected methods or properties in PHP classes. By the end of this lesson you will learn how to make things private at first, protected once you need to access them in a subclass, and public when you need to use it outside of its class and subclass.
Additional resources
In this tutorial, I will show you how to get around the problem of calling a function that you have overridden in your class: how to call the parent class method.
Additional resources
In this tutorial, I will show you how we can build a better blueprint and hierarchical structure for our app’s classes through the use of abstract classes.
Additional resources
In this tutorial, I will show you the power of abstract classes and how you can enforce subclasses to define certain functions. In this way, you can share logic but for things that are really specific to subclasses, you can force them to define certain functions, but with the specific logic required.
Additional resources
In this tutorial, I will show you how to extend an abstract class and ensure that all the methods that are required by the abstract class are included in this new class.
Additional resources
In this tutorial, I will show you how to handle new requirements for data storage by creating two smaller abstract classes out of our original data storage class. By creating these new abstract classes, we can build more flexibility into our code.
Additional resources
Now that we have created new abstract classes, we need to load and utilize them in our code. In this tutorial, I will show you how we can refactor our code to make use of our new abstract data loading classes.
We have an abstract class with methods that we require, but there’s no logic in these abstract methods. This is a perfect opportunity to use interfaces. In this tutorial, I will show you how to create and implement Interfaces. I will also explain how interfaces are useful when you will be sharing your code. But even if you’re not creating interfaces to share, chances are, if you’re using open source code — and definitely in Drupal — you will need to know how to implement interfaces.
Additional resources
In this tutorial, we'll create a new module and create a route and controller for it. Remember hook_menu
? Well, hook_menu
is out and routes and controllers are in! If the YAML files in this lesson piqued your interest, check out our introduction to YAML tutorial to learn more.
Note: See Create an Info File for a Module for up-to-date instructions on info file requirements, which have changed since this video was recorded.
Additional resources
Create an Info File for a Module
An Introduction to YAML — Drupalize.Me
PHP Namespaces in 120 seconds
Clear Drupal's Cache
In this tutorial, we'll continue to look under the hood of Drupal 8, this time using a tool bundled with Devel called Webprofiler. You'll learn how to use the web debug toolbar and the profiler. You'll also learn how to reverse engineer a page to find out the names of the controllers responsible for output on that page.
Note: Webprofiler is now a separate project from Devel but still has it as a dependency.
Note: In order to get the Webprofiler timeline view working you need to add some configuration to your settings.php file. See the README.md file included with the Webprofiler module for more information on how to do this.
Additional resources
YAML, which stands for YAML Ain't Markup Language, is a human-readable data serialization format that's been widely adopted in a variety of use cases in Drupal. Anyone wanting to write modules, or themes, for Drupal will need to understand YAML syntax. Even site builders are likely to encounter YAML at least in passing as YAML is the data-serialization format of choice for Drupal's configuration management system. Good thing it's pretty easy to learn even with the most basic of programming backgrounds.
This tutorial will look at the YAML data format and provide examples of how to write and read YAML. Starting with an introduction to the language's syntax and some of the strengths of YAML. Then looking at the difference between scalar data types like strings and integers, and collection data types like lists and associative arrays.
Since YAML in the Drupal world is read into PHP and ultimately becomes a PHP data structure that we can use in our own code we'll also look at how the YAML we write in a .yml file is represented in PHP data types. To do this we'll use the YAML Sandbox module that provides a handy textarea into which we can type YAML and have it parsed into PHP data structures.
Learning objectives
- Explain what YAML is and its strengths as a data serialization format
- Create scalar key/value pairs in YAML
- Create lists, and associative arrays using YAML collections
- Understand how the YAML you write is represented in PHP
Tips
- In Drupal, use the .yml extension and not .yaml
- Ensure your code editing application is configured to use spaces (preferably 2 spaces, as per Drupal coding standards), not the tab character when the TAB key is pressed. If you have tab characters in a YAML file within a Drupal environment, a fatal PHP error will be thrown and you'll see a White Screen of Death (WSOD).
- Copy and paste from an existing YAML file to ensure the formatting is correct, and edit from there.
Additional resources
- http://www.yaml.org
- YAML Sandbox module
- Find other tutorials and external resources related to YAML on our YAML topic page (Drupalize.Me)
In this PHP tutorial, you'll get the project files up and running and learn all about class constants in object-oriented PHP.
If you're serious about getting really good at this stuff, code along with me. To do that, download the source code from this page, unzip it, and move into the start directory. When you do that, you'll have the same code that I have here. Open up the README file and follow the instructions inside to get things setup.
When that's done, open your favorite terminal application, move into the directory, and — like we've done in the previous courses — start the built-in php web server by running:
php -S localhost:8000
This is a great server to use for development. Then, in our browser, we can go to http://localhost:8000. Here is our beautiful Battles app!
Additional resources
Introduction to Object-Oriented PHP (Drupalize.Me)
Object-Oriented PHP Part 2 (Drupalize.Me)
Object-Oriented PHP Part 3 (Drupalize.Me)
In this PHP tutorial, you'll be introduced to static methods, the self
keyword and how they are used.
Additional resources
Object-Oriented PHP (topic) (Drupalize.Me)
In this PHP tutorial, we'll continue learning about static methods and when to use static vs. non-static methods.