[Bug]: HTML output of Table is missing colgroup element (#4281)

* [Bug]: HTML output of Table is missing colgroup element
Fixes #4280

* Fixed typo and added some documentation

demos/src/Nodes/Table/React/index.spec.js

@@ -63,7 +63,7 @@ context('/src/Nodes/Table/React/', () => {
       const html = editor.getHTML()
 
       expect(html).to.equal(
-        '<table><tbody><tr><td colspan="1" rowspan="1"><p></p></td></tr></tbody></table>',
+        '<table style="minWidth: 25px"><colgroup><col></colgroup><tbody><tr><td colspan="1" rowspan="1"><p></p></td></tr></tbody></table>',
       )
     })
   })
@@ -75,7 +75,7 @@ context('/src/Nodes/Table/React/', () => {
       const html = editor.getHTML()
 
       expect(html).to.equal(
-        '<table><tbody><tr><th colspan="1" rowspan="1"><p></p></th></tr></tbody></table>',
+        '<table style="minWidth: 25px"><colgroup><col></colgroup><tbody><tr><th colspan="1" rowspan="1"><p></p></th></tr></tbody></table>',
       )
     })
   })

demos/src/Nodes/Table/Vue/index.spec.js

@@ -62,7 +62,7 @@ context('/src/Nodes/Table/Vue/', () => {
 
       const html = editor.getHTML()
 
-      expect(html).to.equal('<table><tbody><tr><td colspan="1" rowspan="1"><p></p></td></tr></tbody></table>')
+      expect(html).to.equal('<table style="minWidth: 25px"><colgroup><col></colgroup><tbody><tr><td colspan="1" rowspan="1"><p></p></td></tr></tbody></table>')
     })
   })
 
@@ -72,7 +72,7 @@ context('/src/Nodes/Table/Vue/', () => {
 
       const html = editor.getHTML()
 
-      expect(html).to.equal('<table><tbody><tr><th colspan="1" rowspan="1"><p></p></th></tr></tbody></table>')
+      expect(html).to.equal('<table style="minWidth: 25px"><colgroup><col></colgroup><tbody><tr><th colspan="1" rowspan="1"><p></p></th></tr></tbody></table>')
     })
   })
 

packages/extension-table/src/table.ts

@@ -22,8 +22,10 @@ import {
   toggleHeaderCell,
 } from '@tiptap/pm/tables'
 import { NodeView } from '@tiptap/pm/view'
+import { DOMOutputSpec } from 'prosemirror-model'
 
 import { TableView } from './TableView.js'
+import { createColGroup } from './utilities/createColGroup.js'
 import { createTable } from './utilities/createTable.js'
 import { deleteTableWhenAllCellsSelected } from './utilities/deleteTableWhenAllCellsSelected.js'
 
@@ -110,8 +112,24 @@ export const Table = Node.create<TableOptions>({
     return [{ tag: 'table' }]
   },
 
-  renderHTML({ HTMLAttributes }) {
-    return ['table', mergeAttributes(this.options.HTMLAttributes, HTMLAttributes), ['tbody', 0]]
+  renderHTML({ node, HTMLAttributes }) {
+    const { colgroup, tableWidth, tableMinWidth } = createColGroup(
+      node,
+      this.options.cellMinWidth,
+    )
+
+    const table: DOMOutputSpec = [
+      'table',
+      mergeAttributes(this.options.HTMLAttributes, HTMLAttributes, {
+        style: tableWidth
+          ? `width: ${tableWidth}`
+          : `minWidth: ${tableMinWidth}`,
+      }),
+      colgroup,
+      ['tbody', 0],
+    ]
+
+    return table
   },
 
   addCommands() {

packages/extension-table/src/utilities/createColGroup.ts

@@ -0,0 +1,51 @@
+import { Node as ProseMirrorNode } from '@tiptap/pm/model'
+import { DOMOutputSpec } from 'prosemirror-model'
+
+/**
+ * Creates a colgroup element for a table node in ProseMirror.
+ *
+ * @param node - The ProseMirror node representing the table.
+ * @param cellMinWidth - The minimum width of a cell in the table.
+ * @param overrideCol - (Optional) The index of the column to override the width of.
+ * @param overrideValue - (Optional) The width value to use for the overridden column.
+ * @returns An object containing the colgroup element, the total width of the table, and the minimum width of the table.
+ */
+export function createColGroup(
+  node: ProseMirrorNode,
+  cellMinWidth: number,
+  overrideCol?: number,
+  overrideValue?: any,
+) {
+  let totalWidth = 0
+  let fixedWidth = true
+  const cols: DOMOutputSpec[] = []
+  const row = node.firstChild
+
+  if (!row) {
+    return {}
+  }
+
+  for (let i = 0, col = 0; i < row.childCount; i += 1) {
+    const { colspan, colwidth } = row.child(i).attrs
+
+    for (let j = 0; j < colspan; j += 1, col += 1) {
+      const hasWidth = overrideCol === col ? overrideValue : colwidth && colwidth[j]
+      const cssWidth = hasWidth ? `${hasWidth}px` : ''
+
+      totalWidth += hasWidth || cellMinWidth
+
+      if (!hasWidth) {
+        fixedWidth = false
+      }
+
+      cols.push(['col', cssWidth ? { style: `width: ${cssWidth}` } : {}])
+    }
+  }
+
+  const tableWidth = fixedWidth ? `${totalWidth}px` : ''
+  const tableMinWidth = fixedWidth ? '' : `${totalWidth}px`
+
+  const colgroup: DOMOutputSpec = ['colgroup', {}, ...cols]
+
+  return { colgroup, tableWidth, tableMinWidth }
+}