Hvordan lage en moderne webapp ved hjelp av WordPress og React

Kombiner kraften til en React-frontend med internettets mest populære CMS

Vil du ha fordelene med et moderne React SPA, men trenger en back-end som føles kjent? I denne artikkelen vil vi gå gjennom hvordan du konfigurerer WordPress REST API, inkludert tilpassede innleggstyper og felt, og hvordan du henter disse dataene i React.

Nylig jobbet jeg med en React-app for en klient da de spurte meg om dette spørsmålet: 'Kan vi bruke det med WordPress ? '

Siden slutten av 2015 har svaret på dette spørsmålet vært ja. Men trinnene som er nødvendige for å opprette et fungerende frakoblet nettsted, virker kanskje ikke greie, spesielt for de som ikke er kjent med både WordPress og React.

På reisen min for å lage et fungerende program, opplevde jeg en håndfull vanskelige hindringer, og i denne artikkelen vil jeg forklare hvordan jeg kan unngå dem. Jeg vil også dele flere tips og triks jeg lærte underveis!

Innhold

Del 1: Bakgrunnsinformasjon

  • Hva er et hodeløst CMS?
  • Hva bør jeg vite å følge med?
  • Viktige akronymer
  • Hvor kan jeg se WordPresss JSON-data?

Del 2: WordPress

  • Legge til en tilpasset innleggstype
  • Endring av tittel plassholdertekst
  • Legge til et egendefinert felt i din tilpassede innleggstype
  • Gjør tilpassede felt tilgjengelige som JSON
  • Begrensning av synlige JSON-data

Del 3: Reager

  • Løfter i JavaScript
  • Hentemetoden
  • Håndtering av løfter

Et arbeidseksempel i React

Konklusjon

Del 1: Bakgrunnsinformasjon

Hva er et hodeløst CMS?

Tidligere betydde bruk av et CMS som WordPress at du måtte bygge din frontend ved hjelp av PHP.

Nå, med et hodeløst CMS, kan du bygge frontendene dine med den teknologien du liker; Dette er på grunn av separasjonen av front-end og back-end via en API. Hvis du vil lage et SPA (ensidig applikasjon) ved hjelp av React, Angular eller Vue, og kontrollere innholdet ved hjelp av et CMS som WordPress, kan du!

Hva bør jeg vite å følge med?

Du får mest mulig ut av denne artikkelen hvis du har:

  • litt kunnskap om hvordan et CMS som WordPress fungerer, litt PHP, og en idé om hvordan du setter opp et grunnleggende WordPress-prosjekt på datamaskinen din;
  • en forståelse av JavaScript, inkludert ES6 + språkfunksjoner og React-klassesyntaks.

Viktige akronymer

Programmering er full av sjargong, men det gjør det mye raskere å diskutere noen av konseptene i denne artikkelen. Her er et raskt sammendrag av vilkårene vi skal bruke:

  • CMS - innholdsstyringssystem. Tenk WordPress, Drupal, Joomla, Magneto.
  • SPA - applikasjon på én side. I stedet for å laste inn hver side i sin helhet, laster et SPA-program innhold dynamisk. Den grunnleggende koden (HTML, CSS og JavaScript) på nettstedet lastes inn bare én gang. Think React, Vue, Angular.
  • API - applikasjonsprogrammeringsgrensesnitt. Enkelt sagt, en rekke definisjoner, som en tjeneste gir for å tillate deg å ta og bruke dataene. Google Maps har en. Medium har en. Og nå kommer hvert WordPress-nettsted med en innebygd API.
  • REST - representasjonsstatlig overføring. En stil av web-arkitektur basert rundt HTTP forespørsel metoder: GET, PUT, POSTog DELETE. WordPress's innebygde API er en REST eller "RESTful" API.
  • HTTP - protokoll for overføring av hypertekst. Regelsettet som brukes til å overføre data over nettet. Det er spesifisert i begynnelsen av nettadresser som httpeller https(den sikre versjonen).
  • JSON - JavaScript-objektnotasjon. Selv om det kommer fra JavaScript, er dette et språkuavhengig format for lagring og overføring av data.

I denne artikkelen bruker vi WordPress som vårt CMS. Det betyr å programmere back-enden vår i PHP og bruke WordPress's REST API for å levere JSON-data til vår frontend.

Hvor kan jeg se WordPresss JSON-data?

Før du kommer til de gode tingene, et raskt notat om hvor du kan finne JSON-dataene på WordPress-siden din. I dag har hvert WordPress-nettsted JSON-data tilgjengelig (med mindre nettstedseieren har deaktivert eller begrenset tilgangen til det). Du ser på hoved-JSON på et WordPress-nettsted ved å legge /wp-jsontil rotdomenet.

Så for eksempel kan du ta en titt på JSON for WordPress.org ved å gå til //wordpress.org/wp-json. Eller hvis du kjører et WordPress-nettsted lokalt, kan du se dets JSON ved å følge localhost/yoursitename/wp-json.

For å få tilgang til dataene for innleggene dine, skriv inn localhost/yoursitename/wp-json/wp/v2/posts. For et tilpasset innleggsformat, bytt i det nye formatet (f.eks. movies) I stedet for posts. Det som nå ser ut som en uleselig tekstblokk, er akkurat det som gjør at vi kan bruke WordPress som et hodeløst CMS!

Del 2: WordPress

For å konfigurere REST API, vil det meste du må gjøre skje i functions.phpfilen din . Jeg antar at du vet hvordan du setter opp et WordPress-prosjekt og får tilgang til det ved hjelp av localhost, men hvis du vil ha litt hjelp med det, anbefaler jeg denne artikkelen (det er det jeg pleide å komme i gang med programmering med WordPress).

For de fleste prosjekter vil du bruke en tilpasset innleggstype, så la oss begynne med å sette opp en.

Legge til en tilpasset innleggstype

La oss si at nettstedet vårt handler om filmer, og vi vil ha en innleggstype som heter 'filmer'. Først vil vi sørge for at innleggstypen 'filmer' lastes inn så snart som mulig, så vi fester den på initkroken ved å bruke add_action:

add_action( 'init', 'movies_post_type' );

Jeg bruker movies_post_type(), men du kan kalle funksjonen din hva du vil.

Deretter ønsker vi å registrere 'filmer' som innleggstype ved hjelp av register_post_type()funksjonen.

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

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.