OpenAPI: Remove undefined values in generated frontmatter

.changeset/itchy-boats-follow.md

@@ -0,0 +1,5 @@
+---
+'fumadocs-openapi': patch
+---
+
+Remove undefined values in generated frontmatter

packages/core/src/utils/remove-undefined.ts

@@ -1,13 +1,19 @@
 export function removeUndefined<T extends object>(value: T, deep = false): T {
   const obj = value as Record<string, unknown>;
 
-  for (const key of Object.keys(obj)) {
+  for (const key in obj) {
     if (obj[key] === undefined) delete obj[key];
+    if (!deep) continue;
 
-    if (deep && typeof obj[key] === 'object' && obj[key] !== null) {
-      removeUndefined(obj[key], deep);
-    } else if (deep && Array.isArray(obj[key])) {
-      obj[key].forEach((v) => removeUndefined(v, deep));
+    const entry = obj[key];
+
+    if (typeof entry === 'object' && entry !== null) {
+      removeUndefined(entry, deep);
+      continue;
+    }
+
+    if (Array.isArray(entry)) {
+      for (const item of entry) removeUndefined(item, deep);
     }
   }
 

packages/openapi/src/generate.ts

@@ -12,6 +12,7 @@ import type { Document, TagObject } from '@/types';
 import { dump } from 'js-yaml';
 import type { NoReference } from '@/utils/schema';
 import Slugger from 'github-slugger';
+import { removeUndefined } from '@/utils/remove-undefined';
 
 export interface GenerateOptions {
   /**
@@ -231,7 +232,7 @@ export function generateDocument(
 ): string {
   const { addGeneratedComment = true, imports } = options;
   const out: string[] = [];
-  const banner = dump(frontmatter).trim();
+  const banner = dump(removeUndefined(frontmatter as object)).trimEnd();
   if (banner.length > 0) out.push(`---\n${banner}\n---`);
 
   if (addGeneratedComment) {

packages/openapi/src/utils/remove-undefined.ts

@@ -0,0 +1,21 @@
+export function removeUndefined<T extends object>(value: T, deep = false): T {
+  const obj = value as Record<string, unknown>;
+
+  for (const key in obj) {
+    if (obj[key] === undefined) delete obj[key];
+    if (!deep) continue;
+
+    const entry = obj[key];
+
+    if (typeof entry === 'object' && entry !== null) {
+      removeUndefined(entry, deep);
+      continue;
+    }
+
+    if (Array.isArray(entry)) {
+      for (const item of entry) removeUndefined(item, deep);
+    }
+  }
+
+  return value;
+}