fix: Handle simple numbered lists

This works around a bug in notion-to-md and allows us to handle simple numbered lists.
It will not handle lists that are continued after other content.

Author: JohnThomson

src/CalloutTransformer.ts

@@ -79,7 +79,7 @@ type Annotations = {
     | "pink_background"
     | "red_background";
 };
-type Text = {
+export type Text = {
   type: "text";
   text: {
     content: string;

src/CustomTranformers.ts

@@ -7,6 +7,7 @@ import {
   ListBlockChildrenResponseResults,
 } from "notion-to-md/build/types";
 import { notionCalloutToAdmonition } from "./CalloutTransformer";
+import { numberedListTransformer } from "./NumberedListTransforer";
 
 export function setupCustomTransformers(
   notionToMarkdown: NotionToMarkdown,
@@ -90,6 +91,12 @@ export function setupCustomTransformers(
       notionCalloutToAdmonition(notionToMarkdown, notionClient, block)
   );
 
+  notionToMarkdown.setCustomTransformer(
+    "numbered_list_item",
+    (block: ListBlockChildrenResponseResult) =>
+      numberedListTransformer(notionToMarkdown, notionClient, block)
+  );
+
   // Note: Pull.ts also adds an image transformer, but has to do that for each
   // page so we don't do it here.
 }

src/NumberedListTransforer.ts

@@ -0,0 +1,54 @@
+import { NotionToMarkdown } from "notion-to-md";
+import { ListBlockChildrenResponseResult } from "notion-to-md/build/types";
+import { Client } from "@notionhq/client";
+import { Text } from "./CalloutTransformer";
+
+// This is mostly what notion-to-markdown would normally do with a block of type
+// numbered_list_item. A patch is documented at the end.
+export function numberedListTransformer(
+  notionToMarkdown: NotionToMarkdown,
+  notionClient: Client,
+  block: ListBlockChildrenResponseResult
+): Promise<string> {
+  //console.log("got numbered list block " + JSON.stringify(block));
+  // In this case typescript is not able to index the types properly, hence ignoring the error
+  // @ts-ignore
+  const blockContent =
+    // @ts-ignore
+    block.numbered_list_item?.text || block.numbered_list_item?.rich_text || [];
+  let parsedData = "";
+  blockContent.map((content: Text) => {
+    const annotations = content.annotations;
+    let plain_text = content.plain_text;
+
+    plain_text = notionToMarkdown.annotatePlainText(plain_text, annotations);
+
+    // if (content["href"])
+    //   plain_text = md.link(plain_text, content["href"]);
+
+    parsedData += plain_text;
+  });
+
+  // There is code in notion-to-md which attempts to set an incrementing number
+  // on each of these. Somehow it fails; in my testing, block.numbered_list_item never
+  // has a field 'number'. But we don't actually need incrementing numbers;
+  // markdown will do the numbering if we just make something that looks like
+  // a member of a numbered list by starting with number followed by period and space.
+  // I'm keeping the original code in case notion-to-md gets fixed and there is actually
+  // some reason to use incrementing numbers (it would at least make the markdown more
+  // human-readable); but this at least works.
+  // A problem is that in notion, a numbered list may continue after some intermediate
+  // content. To achieve this in markdown, we'd need to indent the intermediate content
+  // by a tab. Not only is it difficult to do this, but there appears to be no way to
+  // know whether we should. The data we get from notion doesn't include the item number,
+  // and its parent is the page rather than a particular list. So there is no way I can
+  // see to distinguish a list continuation from a new list. The code here will leave
+  // it up to markdown to decide whether to start a new list; I believe it will do so
+  // if it sees any intervening lines that are not list items.
+  let num = block.numbered_list_item?.number;
+  //console.log("got number " + num?.toString());
+  if (!num) {
+    num = 1;
+  }
+  return Promise.resolve(`${num}. ${parsedData.trim()}`);
+}