Retain bullet style after editing a page with lists in content editor

app/assets/javascripts/content_editor/extensions/bullet_list.js

-export { BulletList as default } from '@tiptap/extension-bullet-list';
+import { BulletList } from '@tiptap/extension-bullet-list';
+import { getMarkdownSource } from '../services/markdown_sourcemap';
+
+export default BulletList.extend({
+  addAttributes() {
+    return {
+      ...this.parent?.(),
+
+      bullet: {
+        default: '*',
+        parseHTML(element) {
+          const bullet = getMarkdownSource(element)?.charAt(0);
+
+          return { bullet: '*+-'.includes(bullet) ? bullet : '*' };
+        },
+      },
+    };
+  },
+});

app/assets/javascripts/content_editor/services/markdown_serializer.js

@@ -161,8 +161,6 @@ const defaultSerializerConfig = {
   },
 };
 
-const wrapHtmlPayload = (payload) => `<div>${payload}</div>`;
-
 /**
  * A markdown serializer converts arbitrary Markdown content
  * into a ProseMirror document and viceversa. To convert Markdown
@@ -187,15 +185,15 @@ export default ({ render = () => null, serializerConfig }) => ({
   deserialize: async ({ schema, content }) => {
     const html = await render(content);
 
-    if (!html) {
-      return null;
-    }
+    if (!html) return null;
 
     const parser = new DOMParser();
-    const {
-      body: { firstElementChild },
-    } = parser.parseFromString(wrapHtmlPayload(html), 'text/html');
-    const state = ProseMirrorDOMParser.fromSchema(schema).parse(firstElementChild);
+    const { body } = parser.parseFromString(html, 'text/html');
+
+    // append original source as a comment that nodes can access
+    body.append(document.createComment(content));
+
+    const state = ProseMirrorDOMParser.fromSchema(schema).parse(body);
 
     return state.toJSON();
   },

app/assets/javascripts/content_editor/services/markdown_sourcemap.js

+const getFullSource = (element) => {
+  const commentNode = element.ownerDocument.body.lastChild;
+
+  if (commentNode.nodeName === '#comment') {
+    return commentNode.textContent.split('\n');
+  }
+
+  return [];
+};
+
+const getRangeFromSourcePos = (sourcePos) => {
+  const [start, end] = sourcePos.split('-');
+  const [startRow, startCol] = start.split(':');
+  const [endRow, endCol] = end.split(':');
+
+  return {
+    start: { row: Number(startRow) - 1, col: Number(startCol) - 1 },
+    end: { row: Number(endRow) - 1, col: Number(endCol) - 1 },
+  };
+};
+
+export const getMarkdownSource = (element) => {
+  if (!element.dataset.sourcepos) return undefined;
+
+  const source = getFullSource(element);
+  const range = getRangeFromSourcePos(element.dataset.sourcepos);
+  let elSource = '';
+
+  for (let i = range.start.row; i <= range.end.row; i += 1) {
+    if (i === range.start.row) {
+      elSource += source[i]?.substring(range.start.col);
+    } else if (i === range.end.row) {
+      elSource += `\n${source[i]?.substring(0, range.start.col)}`;
+    } else {
+      elSource += `\n${source[i]}` || '';
+    }
+  }
+
+  return elSource.trim();
+};

spec/frontend/content_editor/extensions/attachment_spec.js

@@ -76,9 +76,7 @@ describe('content_editor/extensions/attachment', () => {
       const base64EncodedFile = 'data:image/png;base64,Zm9v';
 
       beforeEach(() => {
-        renderMarkdown.mockResolvedValue(
-          loadMarkdownApiResult('project_wiki_attachment_image').body,
-        );
+        renderMarkdown.mockResolvedValue(loadMarkdownApiResult('project_wiki_attachment_image'));
       });
 
       describe('when uploading succeeds', () => {
@@ -153,7 +151,7 @@ describe('content_editor/extensions/attachment', () => {
     });
 
     describe('when the file has a zip (or any other attachment) mime type', () => {
-      const markdownApiResult = loadMarkdownApiResult('project_wiki_attachment_link').body;
+      const markdownApiResult = loadMarkdownApiResult('project_wiki_attachment_link');
 
       beforeEach(() => {
         renderMarkdown.mockResolvedValue(markdownApiResult);

spec/frontend/content_editor/extensions/code_block_highlight_spec.js

@@ -11,10 +11,8 @@ describe('content_editor/extensions/code_block_highlight', () => {
   const preElement = () => parsedCodeBlockHtmlFixture.querySelector('pre');
 
   beforeEach(() => {
-    const { html } = loadMarkdownApiResult('code_block');
-
     tiptapEditor = createTestEditor({ extensions: [CodeBlockHighlight] });
-    codeBlockHtmlFixture = html;
+    codeBlockHtmlFixture = loadMarkdownApiResult('code_block');
     parsedCodeBlockHtmlFixture = parseHTML(codeBlockHtmlFixture);
 
     tiptapEditor.commands.setContent(codeBlockHtmlFixture);

spec/frontend/content_editor/markdown_processing_examples.js

@@ -6,7 +6,8 @@ import { getJSONFixture } from 'helpers/fixtures';
 export const loadMarkdownApiResult = (testName) => {
   const fixturePathPrefix = `api/markdown/${testName}.json`;
 
-  return getJSONFixture(fixturePathPrefix);
+  const fixture = getJSONFixture(fixturePathPrefix);
+  return fixture.body || fixture.html;
 };
 
 export const loadMarkdownApiExamples = () => {
@@ -16,3 +17,9 @@ export const loadMarkdownApiExamples = () => {
 
   return apiMarkdownExampleObjects.map(({ name, context, markdown }) => [name, context, markdown]);
 };
+
+export const loadMarkdownApiExample = (testName) => {
+  return loadMarkdownApiExamples().find(([name, context]) => {
+    return (context ? `${context}_${name}` : name) === testName;
+  })[2];
+};

spec/frontend/content_editor/markdown_processing_spec.js

@@ -9,8 +9,9 @@ describe('markdown processing', () => {
     'correctly handles %s (context: %s)',
     async (name, context, markdown) => {
       const testName = context ? `${context}_${name}` : name;
-      const { html, body } = loadMarkdownApiResult(testName);
-      const contentEditor = createContentEditor({ renderMarkdown: () => html || body });
+      const contentEditor = createContentEditor({
+        renderMarkdown: () => loadMarkdownApiResult(testName),
+      });
       await contentEditor.setSerializedContent(markdown);
 
       expect(contentEditor.getSerializedContent()).toBe(markdown);

spec/frontend/content_editor/services/markdown_sourcemap_spec.js

+import { Extension } from '@tiptap/core';
+import BulletList from '~/content_editor/extensions/bullet_list';
+import ListItem from '~/content_editor/extensions/list_item';
+import Paragraph from '~/content_editor/extensions/paragraph';
+import markdownSerializer from '~/content_editor/services/markdown_serializer';
+import { getMarkdownSource } from '~/content_editor/services/markdown_sourcemap';
+import { loadMarkdownApiResult, loadMarkdownApiExample } from '../markdown_processing_examples';
+import { createTestEditor, createDocBuilder } from '../test_utils';
+
+const SourcemapExtension = Extension.create({
+  // lets add `source` attribute to every element using `getMarkdownSource`
+  addGlobalAttributes() {
+    return [
+      {
+        types: [Paragraph.name, BulletList.name, ListItem.name],
+        attributes: {
+          source: {
+            parseHTML: (element) => {
+              const source = getMarkdownSource(element);
+              if (source) return { source };
+              return {};
+            },
+          },
+        },
+      },
+    ];
+  },
+});
+
+const tiptapEditor = createTestEditor({
+  extensions: [BulletList, ListItem, SourcemapExtension],
+});
+
+const {
+  builders: { doc, bulletList, listItem, paragraph },
+} = createDocBuilder({
+  tiptapEditor,
+  names: {
+    bulletList: { nodeType: BulletList.name },
+    listItem: { nodeType: ListItem.name },
+  },
+});
+
+describe('content_editor/services/markdown_sourcemap', () => {
+  it('gets markdown source for a rendered HTML element', async () => {
+    const deserialized = await markdownSerializer({
+      render: () => loadMarkdownApiResult('bullet_list_style_3'),
+      serializerConfig: {},
+    }).deserialize({
+      schema: tiptapEditor.schema,
+      content: loadMarkdownApiExample('bullet_list_style_3'),
+    });
+
+    const expected = doc(
+      bulletList(
+        { bullet: '+', source: '+ list item 1\n+ list item 2' },
+        listItem({ source: '+ list item 1' }, paragraph('list item 1')),
+        listItem(
+          { source: '+ list item 2' },
+          paragraph('list item 2'),
+          bulletList(
+            { bullet: '-', source: '- embedded list item 3' },
+            listItem({ source: '- embedded list item 3' }, paragraph('embedded list item 3')),
+          ),
+        ),
+      ),
+    );
+
+    expect(deserialized).toEqual(expected.toJSON());
+  });
+});

spec/frontend/fixtures/api_markdown.yml

@@ -66,11 +66,21 @@
 - name: thematic_break
   markdown: |-
     ---
-- name: bullet_list
+- name: bullet_list_style_1
   markdown: |-
     * list item 1
     * list item 2
       * embedded list item 3
+- name: bullet_list_style_2
+  markdown: |-
+    - list item 1
+    - list item 2
+      * embedded list item 3
+- name: bullet_list_style_3
+  markdown: |-
+    + list item 1
+    + list item 2
+      - embedded list item 3
 - name: ordered_list
   markdown: |-
     1. list item 1