Merge pull request #16 from Q42/fix/slug-validator-error-message

Fix: slug validator error message

src/validators/slug-validator.ts

@@ -19,12 +19,22 @@ export const slugValidator =
     const allPages = await client.fetch<RawPageMetadata[]>(getRawPageMetadataQuery(config));
     const siblingPages = allPages.filter(page => page.parent?._ref === parentRef._ref);
 
-    const hasDuplicateSlugWithinParent = siblingPages
-      .filter(child => child._id.replace(DRAFTS_PREFIX, '') !== context.document?._id.replace(DRAFTS_PREFIX, ''))
-      .some(child => child.slug?.current === slug?.current);
+    const siblingPagesWithSameSlug = siblingPages
+      .filter(page => page._id.replace(DRAFTS_PREFIX, '') !== context.document?._id.replace(DRAFTS_PREFIX, ''))
+      .filter(page => page.slug?.current === slug?.current);
 
-    if (hasDuplicateSlugWithinParent) {
-      return 'Slug must be unique.';
+    if (siblingPagesWithSameSlug.length) {
+      // If there is a sibling page with the same slug published, but a different slug in a draft, we want to show a more specific validation error to the user instead.
+      const siblingDraftPageWithSameSlug = siblingPages.find(
+        page =>
+          page._id.startsWith(DRAFTS_PREFIX) &&
+          page._id.includes(siblingPagesWithSameSlug[0]._id) &&
+          page.slug?.current !== slug?.current,
+      );
+
+      return siblingDraftPageWithSameSlug
+        ? `Slug must be unique. Another page with the same slug is already published, but has a draft version with a  different slug: "${siblingDraftPageWithSameSlug.slug?.current}". Publish that page first or change the slug to something else.`
+        : 'Slug must be unique.';
     }
 
     return true;