@ckeditor/ckeditor5-table
Version:
Table feature for CKEditor 5.
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TypeScript
/**
* @license Copyright (c) 2003-2025, CKSource Holding sp. z o.o. All rights reserved.
* For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
*/
/**
* @module table/converters/table-layout-post-fixer
*/
import type { Model } from 'ckeditor5/src/engine.js';
/**
* Injects a table layout post-fixer into the model.
*
* The role of the table layout post-fixer is to ensure that the table rows have the correct structure
* after a {@link module:engine/model/model~Model#change `change()`} block was executed.
*
* The correct structure means that:
*
* * All table rows have the same size.
* * None of the table cells extend vertically beyond their section (either header or body).
* * A table cell has always at least one element as a child.
*
* If the table structure is not correct, the post-fixer will automatically correct it in two steps:
*
* 1. It will clip table cells that extend beyond their section.
* 2. It will add empty table cells to the rows that are narrower than the widest table row.
*
* ## Clipping overlapping table cells
*
* Such situation may occur when pasting a table (or a part of a table) to the editor from external sources.
*
* For example, see the following table which has a cell (FOO) with the rowspan attribute (2):
*
* ```xml
* <table headingRows="1">
* <tableRow>
* <tableCell rowspan="2"><paragraph>FOO</paragraph></tableCell>
* <tableCell colspan="2"><paragraph>BAR</paragraph></tableCell>
* </tableRow>
* <tableRow>
* <tableCell><paragraph>BAZ</paragraph></tableCell>
* <tableCell><paragraph>XYZ</paragraph></tableCell>
* </tableRow>
* </table>
* ```
*
* It will be rendered in the view as:
*
* ```xml
* <table>
* <thead>
* <tr>
* <td rowspan="2">FOO</td>
* <td colspan="2">BAR</td>
* </tr>
* </thead>
* <tbody>
* <tr>
* <td>BAZ</td>
* <td>XYZ</td>
* </tr>
* </tbody>
* </table>
* ```
*
* In the above example the table will be rendered as a table with two rows: one in the header and second one in the body.
* The table cell (FOO) cannot span over multiple rows as it would extend from the header to the body section.
* The `rowspan` attribute must be changed to (1). The value (1) is the default value of the `rowspan` attribute
* so the `rowspan` attribute will be removed from the model.
*
* The table cell with BAZ in the content will be in the first column of the table.
*
* ## Adding missing table cells
*
* The table post-fixer will insert empty table cells to equalize table row sizes (the number of columns).
* The size of a table row is calculated by counting column spans of table cells, both horizontal (from the same row) and
* vertical (from the rows above).
*
* In the above example, the table row in the body section of the table is narrower then the row from the header: it has two cells
* with the default colspan (1). The header row has one cell with colspan (1) and the second with colspan (2).
* The table cell (FOO) does not extend beyond the head section (and as such will be fixed in the first step of this post-fixer).
* The post-fixer will add a missing table cell to the row in the body section of the table.
*
* The table from the above example will be fixed and rendered to the view as below:
*
* ```xml
* <table>
* <thead>
* <tr>
* <td rowspan="2">FOO</td>
* <td colspan="2">BAR</td>
* </tr>
* </thead>
* <tbody>
* <tr>
* <td>BAZ</td>
* <td>XYZ</td>
* </tr>
* </tbody>
* </table>
* ```
*
* ## Collaboration and undo - Expectations vs post-fixer results
*
* The table post-fixer only ensures proper structure without a deeper analysis of the nature of the change. As such, it might lead
* to a structure which was not intended by the user. In particular, it will also fix undo steps (in conjunction with collaboration)
* in which the editor content might not return to the original state.
*
* This will usually happen when one or more users change the size of the table.
*
* As an example see the table below:
*
* ```xml
* <table>
* <tbody>
* <tr>
* <td>11</td>
* <td>12</td>
* </tr>
* <tr>
* <td>21</td>
* <td>22</td>
* </tr>
* </tbody>
* </table>
* ```
*
* and the user actions:
*
* 1. Both users have a table with two rows and two columns.
* 2. User A adds a column at the end of the table. This will insert empty table cells to two rows.
* 3. User B adds a row at the end of the table. This will insert a row with two empty table cells.
* 4. Both users will have a table as below:
*
* ```xml
* <table>
* <tbody>
* <tr>
* <td>11</td>
* <td>12</td>
* <td>(empty, inserted by A)</td>
* </tr>
* <tr>
* <td>21</td>
* <td>22</td>
* <td>(empty, inserted by A)</td>
* </tr>
* <tr>
* <td>(empty, inserted by B)</td>
* <td>(empty, inserted by B)</td>
* </tr>
* </tbody>
* </table>
* ```
*
* The last row is shorter then others so the table post-fixer will add an empty row to the last row:
*
* ```xml
* <table>
* <tbody>
* <tr>
* <td>11</td>
* <td>12</td>
* <td>(empty, inserted by A)</td>
* </tr>
* <tr>
* <td>21</td>
* <td>22</td>
* <td>(empty, inserted by A)</td>
* </tr>
* <tr>
* <td>(empty, inserted by B)</td>
* <td>(empty, inserted by B)</td>
* <td>(empty, inserted by the post-fixer)</td>
* </tr>
* </tbody>
* </table>
* ```
*
* Unfortunately undo does not know the nature of the changes and depending on which user applies the post-fixer changes, undoing them
* might lead to a broken table. If User B undoes inserting the column to the table, the undo engine will undo only the operations of
* inserting empty cells to rows from the initial table state (row 1 and 2) but the cell in the post-fixed row will remain:
*
* ```xml
* <table>
* <tbody>
* <tr>
* <td>11</td>
* <td>12</td>
* </tr>
* <tr>
* <td>21</td>
* <td>22</td>
* </tr>
* <tr>
* <td>(empty, inserted by B)</td>
* <td>(empty, inserted by B)</td>
* <td>(empty, inserted by a post-fixer)</td>
* </tr>
* </tbody>
* </table>
* ```
*
* After undo, the table post-fixer will detect that two rows are shorter than others and will fix the table to:
*
* ```xml
* <table>
* <tbody>
* <tr>
* <td>11</td>
* <td>12</td>
* <td>(empty, inserted by a post-fixer after undo)</td>
* </tr>
* <tr>
* <td>21</td>
* <td>22</td>
* <td>(empty, inserted by a post-fixer after undo)</td>
* </tr>
* <tr>
* <td>(empty, inserted by B)</td>
* <td>(empty, inserted by B)</td>
* <td>(empty, inserted by a post-fixer)</td>
* </tr>
* </tbody>
* </table>
* ```
*/
export default function injectTableLayoutPostFixer(model: Model): void;