Merge branch 'master' of github.com:souvikinator/notion-to-md

Author: souvikinator

README.md

@@ -195,6 +195,26 @@ console.log(result);
 ![image](https://media.giphy.com/media/Ju7l5y9osyymQ/giphy.gif)
 ```
 
+## Custom Transformers
+You can define your own custom transformer for a notion type, to parse and return your own string.
+`setCustomTransformer(type, func)` will overload the parsing for the giving type.
+
+```js
+const { NotionToMarkdown } = require("notion-to-md");
+const n2m = new NotionToMarkdown({ notionClient: notion });
+n2m.setCustomTransformer('embed', async (block) => {
+  const {embed} = block as any;
+  if (!embed?.url) return '';
+  return `<figure>
+  <iframe src="${embed?.url}"></iframe>
+  <figcaption>${await n2m.blockToMarkdown(embed?.caption)}</figcaption>
+</figure>`;
+});
+const result = n2m.blockToMarkdown(block);
+// Result will now parse the `embed` type with your custom function. 
+```
+**Note** Be aware that `setCustomTransformer` will take only the last function for the given type. You can't set two different transforms for the same type.
+
 ## Contribution
 
 Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

src/notion-to-md.spec.ts

@@ -0,0 +1,30 @@
+import  { NotionToMarkdown } from './notion-to-md';
+
+describe("setCustomTransformer", () => {
+
+  test("blockToMarkdown sends parsing block to customTransformer", () => {
+    const customTransformerMock =jest.fn()
+    const n2m = new NotionToMarkdown({notionClient: {} as any})
+    n2m.setCustomTransformer("test", customTransformerMock)
+    n2m.blockToMarkdown({
+      id: "test", name: "test", type: "test", test: {"foo": "bar"}
+    } as any)
+    expect(customTransformerMock).toHaveBeenCalledWith(expect.objectContaining({
+      type: "test", test: {"foo": "bar"}
+    }))
+  })
+  test("supports only one customTransformer per type ", () => {
+    const customTransformerMock1 =jest.fn()
+    const customTransformerMock2 = jest.fn()
+    const n2m = new NotionToMarkdown({notionClient: {} as any})
+    n2m.setCustomTransformer("test", customTransformerMock1)
+    n2m.setCustomTransformer("test", customTransformerMock2)
+    n2m.blockToMarkdown({
+      id: "test", name: "test", type: "test", test: {"foo": "bar"}
+    } as any)
+    expect(customTransformerMock1).not.toHaveBeenCalled()
+    expect(customTransformerMock2).toHaveBeenCalled()
+  })
+
+
+})

src/notion-to-md.ts

@@ -6,6 +6,7 @@ import {
   MdBlock,
   Text,
   NotionToMarkdownOptions,
+  CustomTransformer
 } from "./types";
 import * as md from "./utils/md";
 import { getBlockChildren } from "./utils/notion";
@@ -15,11 +16,16 @@ import { getBlockChildren } from "./utils/notion";
  */
 export class NotionToMarkdown {
   private notionClient: Client;
-
+  private customTransformers: Record<string, CustomTransformer>
   constructor(options: NotionToMarkdownOptions) {
     this.notionClient = options.notionClient;
+    this.customTransformers = {}
   }
+  setCustomTransformer(type: string, transformer: CustomTransformer): NotionToMarkdown {
+    this.customTransformers[type] = transformer;
 
+    return this;
+  }
   /**
    * Converts Markdown Blocks to string
    * @param {MdBlock[]} mdBlocks - Array of markdown blocks
@@ -122,12 +128,13 @@ ${md.addTabSpace(mdBlocks.parent, nestingLevel)}
    * @returns {string} corresponding markdown string of the passed block
    */
   async blockToMarkdown(block: ListBlockChildrenResponseResult) {
-    if (!("type" in block)) return "";
+    if (typeof block !== "object" || !("type" in block)) return "";
 
     let parsedData = "";
     const { type } = block;
-    // console.log({ block });
-
+    if(type in this.customTransformers && !!this.customTransformers[type]) 
+      return await this.customTransformers[type](block);
+    
     switch (type) {
       case "image":
         {
@@ -325,7 +332,6 @@ ${md.addTabSpace(mdBlocks.parent, nestingLevel)}
 
       default: {
         // In this case typescript is not able to index the types properly, hence ignoring the error
-
         // @ts-ignore
         let blockContent = block[type].text || block[type].rich_text || [];
         blockContent.map((content: Text) => {

src/types/index.ts

@@ -6,7 +6,6 @@ export type BlockAttributes = {
     number?: number;
   };
 };
-
 export type ListBlockChildrenResponseResults =
   ListBlockChildrenResponse["results"] & BlockAttributes;
 
@@ -70,3 +69,4 @@ export type CalloutIcon =
   | { type: "external"; external?: { url: string } }
   | { type: "file"; file: { url: string; expiry_time: string } }
   | null;
+export type CustomTransformer = (block: ListBlockChildrenResponseResult) => Promise<string>;