Implementing Decoupled Preview

Before You Begin

Make sure a preview site and client secret is properly configured on your Drupal instance.

1. Log in to your Drupal instance.
2. Navigate to Configuration > SimpleOAuth > Clients
3. Create a new consumer or use the default. Copy the UUID of the consumer you would like to use.
4. Click Edit on the consumer you are using and add a new secret. Note this value down as well. At any time a new CLIENT_SECRET can be generated via the Environment Variables action in the Front-End Sites administration section.
5. We now have a client that can use our preview site. To configure the preview site, navigate to Configuration >> Web Services >> Front-End Sites and click the Add Preview Site button. Note: You will need the Pantheon Decoupled Plugin installed and activated on your instance. Configuring a Preview Site for more information.
6. Set the URL to point to http(s)://{YOUR_SITE_URL}/api/preview replacing {YOUR_SITE_URL} with the URL of your frontend site, or localhost:3000 for testing preview locally.
7. Set a secret for the Preview Site and note this value down.
8. All environment variables needed to configure your Front-End Site can be accessed via the Environment Variables action in the preview site table.

Now you have all of the credentials needed to make authenticated requests to the Drupal instance, including the ability to preview content!

See Setting Environment Variables for more information on how to set these variables in your local development environment or on the Pantheon Dashboard.

Using getPreview

Now that we are set up, we can implement the getPreview helper, which can be found in the lib directory of the next-drupal-starter. This helper takes in two arguments, the current server context as well as the name of the node to be previewed.

// Import some helpers
import { getPreview } from '../../lib/get-preview';
import { isMultiLanguage } from '../../lib/isMultiLanguage';
import {
    getCurrentLocaleStore,
    globalDrupalStateStores,
} from '../../lib/stores';

// your React component here

export async function getStaticProps(context) {
    // Returns a boolean if the site is multilingual
    const multilanguage = isMultilanguage(context.locales);
    // Sets our current language. If preview, use the previewLang,
    // otherwise use the current locale.
    const lang = context.preview
        ? context.previewData.previewLang
        : context.locale;
    // set the store based on the language
    const store = getCurrentLocaleStore(lang, globalDrupalStateStores);
    // gets preview data from the Drupal instance, or in the case of a revision,
    // sets the proper jsonapi param to fetch the revision from Drupal.
    context.preview && getPreview(context, 'node--article');

    // this variable will depend on your route
    const slug = `/articles/${context.params.slug[0]}`;
    // Now we can use the store to get the data we need to render our component
    const article = await store.getObjectByPath('node--article', {
        path: `${multiLanguage ? lang : ''}${slug}`,
    });

    // From here, you can do anything else needed before
    // returning the data to the component.

    return {
        props: { article },
        revalidate: 60,
    };
}

See the articles page from the next-drupal-starter for a full example on using the getPreview helper.

Clearing Current Preview

If you'd like to view another revision or edit, you may need to clear the current previewData cookie. This can be done by going to {YOUR_SITE_URL}/api/clear-preview. On successful clear, you will be redirected to the homepage.

Limitations

Content that is saved as a draft can not be previewed. Currently, preview content must be published or a published revision.