feat: allow adding additional frontmatter via db config

this is useful e.g. to override layout of pages

Author: JohannesRudolph

src/PageMeta.ts

@@ -0,0 +1,12 @@
+/**
+ * Conventional selection of meta information about a Notion API page.
+ * Made availabel as top-level frontmatter on rendered markdown pages
+ */
+export interface PageMeta {
+  id: string;
+  url: string;
+  title: string;
+  category: string;
+  order?: number;
+  layout?: string;
+}

src/PageProperties.ts

@@ -1,23 +1,19 @@
-export interface PageMeta {
-  id: string;
-  url: string;
-  title: string;
-  category: string;
-  order?: number;
-}
+import { PageMeta } from "./PageMeta";
 
 export interface PageProperties {
+  /**
+   * Meta information about a Notion API page
+   */
   meta: PageMeta;
 
   /**
    * A mapping of property object keys -> property values
    */
   values: Record<string, any>;
-  
+
   /**
    * A mapping of Notion API property names -> property object keys
    */
   keys: Map<string, string>;
 }
-
-export interface PagePropertiesWithMeta extends PageProperties {}
+ 

src/PropertiesParser.ts

@@ -59,6 +59,7 @@ export class PropertiesParser {
         title: title, // notion API always calls it name
         category: category,
         order: order,
+        ...config.additionalPageFrontmatter
       },
       values: properties,
       keys: this.sortKeys(config, keys),

src/RenderedPage.ts

@@ -1,4 +1,4 @@
-import { PageMeta } from "./PageProperties";
+import { PageMeta } from "./PageMeta";
 
 export interface RenderedPage {
   file: string;

src/SyncConfig.ts

@@ -48,6 +48,11 @@ export interface DatabaseConfig {
 
   skipMarkdownTable?: boolean;
 
+  /**
+   * Add custom data to the page frontmatter
+   */
+  additionalPageFrontmatter?: Record<string, any>;
+
   /**
    * Configuration options for Notion API page properties
    */