Get preview content with next.js

article.tsx

/**
 * Execute server-side data fetching.
 */
export const getStaticProps: GetStaticProps = async ({ params, preview }) => {
  console.log(`Loading article content, preview mode is ${!!preview}`);

  const slug = params?.slug as string;
  const service = new ArticleService(preview ?? false);
  const article = await service.getArticle(slug);

  if (!article) {
    return { props: {} };
  }

  const props: IArticleProps = {
    article: {
      id: article.system.id,
      codename: article.system.codename,
      body: article.body.resolveHtml(),
      slug: article.slug.value,
      title: article.title.value,
      metadata: {
        title: article.metadata__page_title.value,
      },
    },
  };

  return { props };
};