Comment créer une application Web moderne à l'aide de WordPress et React

Combinez la puissance d'un front-end React avec le CMS le plus populaire d'Internet

Vous voulez les avantages d'un React SPA moderne, mais vous avez besoin d'un back-end qui vous semble familier? Dans cet article, nous verrons comment configurer l'API REST de WordPress, y compris les types et les champs de publication personnalisés, et comment récupérer ces données dans React.

Récemment, je travaillais sur une application React pour un client lorsqu'ils m'ont posé cette question: `` Pouvons-nous l'utiliser avec WordPress ? '

Depuis fin 2015, la réponse à cette question est oui. Mais les étapes nécessaires pour créer un site découplé fonctionnel peuvent ne pas sembler simples, en particulier pour ceux qui ne sont pas familiers avec WordPress et React.

Lors de mon parcours pour créer une application fonctionnelle, j'ai rencontré une poignée d'obstacles délicats, et dans cet article, je vais vous expliquer comment les éviter. Je vais également partager plusieurs trucs et astuces que j'ai appris en cours de route!

Contenu

Partie 1: Informations générales

  • Qu'est-ce qu'un CMS Headless?
  • Que dois-je savoir pour suivre?
  • Acronymes clés
  • Où puis-je voir les données JSON de WordPress?

Partie 2: WordPress

  • Ajout d'un type de publication personnalisé
  • Modification du texte de l'espace réservé au titre
  • Ajout d'un champ personnalisé à votre type de publication personnalisé
  • Rendre les champs personnalisés disponibles au format JSON
  • Restreindre les données JSON visibles

Partie 3: Réagir

  • Promesses en JavaScript
  • La méthode Fetch
  • Gestion des promesses

Un exemple fonctionnel dans React

Conclusion

Partie 1: Informations générales

Qu'est-ce qu'un CMS Headless?

Dans le passé, utiliser un CMS comme WordPress signifiait que vous deviez créer votre frontend en utilisant PHP.

Maintenant, avec un CMS sans tête, vous pouvez construire votre front-end avec toutes les technologies que vous aimez; ceci est dû à la séparation du front-end et du back-end via une API. Si vous souhaitez créer un SPA (application monopage) en utilisant React, Angular ou Vue, et contrôler le contenu à l'aide d'un CMS comme WordPress, vous pouvez!

Que dois-je savoir pour suivre?

Vous tirerez le meilleur parti de cet article si vous avez:

  • une certaine connaissance du fonctionnement d'un CMS comme WordPress, un peu de PHP et une idée sur la façon de mettre en place un projet WordPress de base sur votre ordinateur;
  • une compréhension de JavaScript, y compris les fonctionnalités du langage ES6 + et la syntaxe de la classe React.

Acronymes clés

La programmation est pleine de jargon, mais cela permet de discuter beaucoup plus rapidement de certains des concepts de cet article. Voici un bref récapitulatif des termes que nous utiliserons:

  • CMS - système de gestion de contenu. Pensez à WordPress, Drupal, Joomla, Magneto.
  • SPA - application d'une seule page. Plutôt que de recharger chaque page dans son intégralité, une application SPA charge le contenu de manière dynamique. Le code fondamental (HTML, CSS et JavaScript) du site Web n'est chargé qu'une seule fois. Pensez React, Vue, Angular.
  • API - interface de programmation d'application. En termes simples, une série de définitions, qu'un service fournit pour vous permettre de prendre et d'utiliser ses données. Google Maps en a un. Medium en a un. Et maintenant, chaque site WordPress est livré avec une API intégrée.
  • REST - transfert d'état de représentation. Un style de l' architecture Web basée autour des méthodes de demande de HTTP: GET, PUT, POSTet DELETE. L'API intégrée de WordPress est une API REST ou «RESTful».
  • HTTP - protocole de transfert hypertexte. L'ensemble des règles utilisées pour transférer des données sur le Web. Il est spécifié au début des URL comme httpou https(la version sécurisée).
  • JSON - Notation d'objets JavaScript. Bien que dérivé de JavaScript, il s'agit d'un format indépendant de la langue pour le stockage et le transfert de données.

Dans cet article, nous utilisons WordPress comme CMS. Cela signifie programmer notre back-end en PHP et utiliser l'API REST de WordPress pour fournir des données JSON à notre frontend.

Où puis-je voir les données JSON de WordPress?

Avant de passer aux bonnes choses, une note rapide sur l' endroit où vous pouvez trouver les données JSON sur votre site WordPress. De nos jours, chaque site Web WordPress dispose de données JSON (sauf si le propriétaire du site en a désactivé ou limité l'accès). Vous jetez un œil au JSON principal d'un site WordPress en ajoutant /wp-jsonau nom de domaine racine.

Ainsi, par exemple, vous pouvez jeter un œil au JSON pour WordPress.org en visitant //wordpress.org/wp-json. Ou, si vous exécutez un site WordPress localement, vous pouvez voir son JSON en suivant localhost/yoursitename/wp-json.

Pour accéder aux données de vos publications, saisissez localhost/yoursitename/wp-json/wp/v2/posts. Pour un format de publication personnalisé, permutez dans le nouveau format (par exemple movies) au lieu de posts. Ce qui ressemble maintenant à un bloc de texte illisible est exactement ce qui nous permettra d'utiliser WordPress comme un CMS sans tête!

Part 2: WordPress

To set-up your REST API, most of what you’ll need to do will happen in your functions.php file. I’ll assume you know how to set up a WordPress project and access it using localhost , but if you’d like some help with that, I recommend this article (it’s what I used to get started programming with WordPress).

For most projects, you’ll want to use a custom post type, so let’s begin by setting one up.

Adding a Custom Post Type

Let’s say our site is about films, and we want a post type called ‘movies’. First, we want to make sure our ‘movies’ post type loads as soon as possible, so we’ll attach it to the init hook, using add_action :

add_action( 'init', 'movies_post_type' );

I’m using movies_post_type() , but you can call your function whatever you want.

Next, we want to register ‘movies’ as a post type, using the register_post_type() function.

The next chunk of code may look overwhelming, but it’s relatively simple: our function takes a lot of in-built arguments to control the functionality of your new post type, and most of them are self-explanatory. We’ll store these arguments in our $args array.

One of our arguments, labels , can take many different arguments of its own, so we split that off into a separate array, $labels , giving us:

Two of the most important arguments are 'supports' and 'taxomonies' , because these control which of the native post fields will be accessible in our new post type.

In the above code, we’ve opted for just three 'supports':

  • 'title'— the title of each post.
  • 'editor'— the primary text editor, which we’ll use for our description.
  • 'thumbnail'— the post’s featured image.

To see the full list of what’s available, click here for supports, and here for taxonomies.

Generate WordPress also has a handy tool to help you code custom post types, which can make the process a lot quicker.

Changing Title Placeholder Text

If the title placeholder text “enter title here” could be a little misleading for your custom post type, you can edit this in a separate function:

Adding a Custom Field to Your Custom Post Type

What if you want a field that doesn’t come pre-defined by WordPress? For example, let’s say we want a special field called “Genre”. In that case, you’ll need to use add_meta_boxes() .

For, we need to attach a new function to WordPress’s add_meta_boxes hook:

add_action( 'add_meta_boxes', 'genre_meta_box' );

Inside our new function, we need to call WordPress’s add_meta_box() function, like so:

function genre_meta_box() { add_meta_box( 'global-notice', __( 'Genre', 'sitepoint' ), 'genre_meta_box_callback', 'movies', 'side', 'low' );}

You can read more about this function’s arguments here. For our purposes, the most critical part is the callback function, which we’ve named genre_meta_box_callback . This defines the actual contents on the meta box. We only need a simple text input, so we can use:

function genre_meta_box_callback() { global $post; $custom = get_post_custom($post->ID); $genre = $custom["genre"][0]; ?>

Finally, our custom field won’t save its value unless we tell it to. For this purpose, we can define a new function save_genre() and attach it to WordPress’s save_post hook:

function save_genre(){ global $post; update_post_meta($post->ID, "printer_category", $_POST["printer_category"]);};
add_action( 'save_post', 'save_genre' );

Together, the code used to create the custom field should look something like this:

Making Custom Fields Available as JSON

Our custom posts are automatically available as JSON. For our “movies” post type, our JSON data can be found at localhost/yoursitename/wp-json/wp/v2/movies .

However our custom fields are not automatically part of this, and so we need to add a function to make sure they are also accessible via the REST API.

First, we’ll need to attach a new function to the rest_api_init hook:

add_action( 'rest_api_init', 'register_genre_as_rest_field' );

Then, we can use the in-built register_rest_field() function, like so:

function register_genre_as_rest_field() { register_rest_field( 'movies', 'genre', array( 'get_callback' => 'get_genre_meta_field', 'update_callback' => null, 'schema' => null, ) );};

This function takes an array with get and update callback. For a more straightforward use-case like this, we should only need to specify a 'get_callback' :

function get_genre_meta_field( $object, $field_name, $value ) { return get_post_meta($object['id'])[$field_name][0];};

As a whole, here is the code necessary to register a custom field.

Making Featured Image URLs Available as JSON

Out-of-the-box, WordPress’s REST API doesn’t include URL for your featured images. To make it easier to access this, you can use the following code:

The WordPress filter rest_prepare_posts is dynamic, so we can swap in our custom post type in place of “posts”, such as rest_prepare_movies .

Restricting Visible JSON Data

We almost ready to start pulling in data to our React app, but there’s one more quick optimisation we can make, by limiting the data that is made available.

Some data comes as standard which you may never need in your frontend and — if that’s the case — we can remove it using a filter, like this one. You can find the names of the data types by looking at your /wp-json/wp/v2/movies part of your website.

With that done, once you’ve added a few movies using the WordPress backend, and we have everything we need to start bringing the data into React!

Part 3: React

Original text


To fetch external data in JavaScript, you need to use promises. This will likely have implications for the way you want to structure your React components, and in my case (converting an existing React project), I had to re-write a fair amount of code.

Promises in JavaScript

Promises in JavaScript are used to handle asynchronous actions — things that happen outside the usual step-by-step or “synchronous” order of execution (after hoisting).

The good news is that asynchronous JavaScript is a lot easier than it used to be. Before ES6, we were dependent on callback functions. If multiple callbacks were necessary (and they often were), nesting would lead to code that was very difficult to read, scale and debug — a phenomenon sometimes known as callback hell, or the pyramid of doom!

Promises were introduced in ES6 (or ES2015) to solve that problem, and ES8 (or ES2018) saw the introduction of async ... await , two keywords which further simplify asynchronous functionality. But for our purposes, the most critical promise-based method is fetch() .

The Fetch Method

This method has been available since Chrome 40, and it is an easier-to-use alternative to XMLHttpRequest() .

fetch() returns a promise and so it is “then-able”, meaning that you can use the then() method to process the outcome.

You can add fetch to a method inside your React class component, like so:

fetchPostData() { fetch(`//localhost/yoursitename/wp-json/wp/v2/movies?per_page=100`) .then(response => response.json()) .then(myJSON => { // Logic goes here});}

In the code above, two things are important:

  • First, we are calling a URL with the filter ?per_page=100 appended onto the end. By default, WordPress only shows 10 items per page, and I often find myself wanting to increase that limit.
  • Second, before processing our data, we are using the .json() method. This method is used primarily in relation to fetch(), and it returns the data as a promise and parses the body text as JSON.

In most cases, we’ll want to run this function as soon as our React component has mounted, and we can specify this using the componentDidMount() method:

componentDidMount() { this.fetchPostData();}

Handling Promises

Once you have returned a promise, you have to be careful about handling it in the correct context.

When I first tried to use promises, I spent a while trying to pass that data to variables outside of the scope of the promise. Here are a few rules of thumb:

  • In React, the best way to use promises is via the state. You can use this.setState() to pass promise data into your component’s state.
  • It is best to process, sort and re-arrange your data within a series of then() methods following the initial fetch() . Once any processing is complete, it is best practice to add the data to state within your final then() method.
  • If you want to call any additional functions to process your promise (including within render()) it’s good practice to prevent the function from running until the promise has resolved.
  • So, for example, if you’re passing your promise to this.state.data , you can include a conditional within the body of any functions that depend on it, like below. This can prevent annoying unwanted behaviour!
myPromiseMethod() { if (this.state.data) { // process promise here } else { // what to do before the fetch is successful }}

A Working Example in React

Let’s say we want to pull in the name, description, featured_image and genre of the custom WordPress post type we defined in part 1.

In the following example, we’ll fetch those four elements for each movie and render them.

As so often with React tutorials, the following block of code may look intimidating, but I hope it will seem much simpler when we break it down.

constructor(props)

In this method, we call super(props), define our initial state (an empty data object) and bind three new methods:

  • fetchPostData()
  • renderMovies()
  • populatePageAfterFetch()

componentDidMount()

We want to fetch our data as soon as the component has mounted, so we’ll call fetchPostData() in here.

fetchPostData()

We fetch the JSON from our URL, passing .json() in the first .then() method.

In the second .then() method, we extract the four values we want for every movie entry we’ve fetched and then add them to our newState object.

We then use this.setState(newState) to add this information to this.state.data .

renderMovies()

The conditional if (this.state.data) means that the function will only run once data has been fetched.

In here, we take an array of all our fetched movies from this.state.data and pass it to the function populatePageAfterFetch() .

populatePageAfterFetch()

In this function, we prepare the data for each movie to be rendered. This should look straightforward to anyone who’s used JSX, with one potential stumbling block.

The value of movie.description is not plain text, but HTML markup. To display this, we can use dangerouslySetInnerHTML={{__html: movie.description}} .

Note: The reason this is potentially “dangerous” is that, if your data were hijacked to contain malicious XSS scripts, these would be parsed too. As we’re using our own server/CMS in this article, we shouldn’t need to worry. But if you do want to sanitise your HTML, take a look at DOMPurify.

render()

Finally, we control where our rendered data will appear by calling the renderMovies() method within our chosen iv> tags. We’ve now successfully fetched data from our WordPress site and displayed it!

Conclusion

Overall, I hope this article makes the process of connecting a React front-end to a WordPress back-end as painless as possible.

Like so much in programming, what can look intimidating to begin with quickly becomes second nature with practice!

I’d be very interested to hear about your own experiences using WordPress as a headless CMS, and I’m happy to answer any questions in the comments.