Add post preview handling in static props

Author: ravewebdev

api/wordpress/_global/getPostTypeStaticProps.js

@@ -8,15 +8,17 @@ import getFrontendPage, {frontendPageSeo} from './getFrontendPage'
  * Retrieve static props by post type.
  *
  * @author WebDevStudios
- * @param {string} params   Post params (e.g., slug).
- * @param {string} postType Post Type.
- * @return {object}         Object containing post props and revalidate setting.
+ * @param {string}  params      Post params (e.g., slug).
+ * @param {string}  postType    Post Type.
+ * @param {boolean} preview     Whether requesting preview of post.
+ * @param {object}  previewData Post preview data.
+ * @return {object}             Object containing post props and revalidate setting.
  */
 export default async function getPostTypeStaticProps(
   params,
-  postType
-  // preview = false, // TODO - add preview handling.
-  // previewData = null
+  postType,
+  preview = false,
+  previewData = null
 ) {
   // Set revalidate length (seconds).
   const revalidate = 60 * 5
@@ -59,16 +61,33 @@ export default async function getPostTypeStaticProps(
   // Handle catch-all routes.
   const slug = Array.isArray(params.slug) ? params.slug.join('/') : params.slug
 
+  // Get post identifier (ID or slug).
+  const postId = Number.isInteger(Number(slug)) ? Number(slug) : slug
+
+  // Check if preview mode is active and valid for current post (preview and post IDs or slugs match).
+  const isCurrentPostPreview =
+    preview &&
+    (postId === previewData?.post?.id || postId === previewData?.post?.slug)
+
+  // Check if viewing a draft post.
+  const isDraft = isCurrentPostPreview && 'draft' === previewData?.post?.status
+
+  // Set query variables.
+  const id = isDraft ? previewData.post.id : slug
+  const idType = isDraft ? 'DATABASE_ID' : 'SLUG'
+
   // Retrieve post data.
   const {apolloClient, error, ...postData} = await getPostTypeById(
     postType,
-    slug
+    id,
+    idType
   )
 
   const props = {
     ...postData,
     ...sharedProps,
-    error
+    error,
+    preview: isCurrentPostPreview
   }
 
   // Custom handling for homepage.