"TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4390

Dumluregn · 2020-11-20T16:08:38Z

Type of report

Bug/Task/Feature?

Provide detailed reproduction steps (if any)

Demo was provided by one of users in Angular: ckeditor/ckeditor4-angular#114 (comment).

Expected result

Errors are not thrown.

Actual result

TypeError: Cannot read property 'unselectable' of null error is thrown and CKEditor crashes.

Other details

There is an error that occurs in various frameworks where you try to integrate CKEditor. It was reported in Drupal, Laravel and Angular and now I encountered it while testing ckeditor/ckeditor4-angular#143.

The issue is most probably caused by this line:

topHtml && editor.ui.space( 'top' ).unselectable();
bottomHtml && editor.ui.space( 'bottom' ).unselectable();

Although the issue wasn't reproduced in the CKEditor itself so far, I think it could be worth to at least take a look at it as it makes integrating it a bit more difficult than it should be. It's hard to classify the character of this issue, so it may need to be relabeled.

The text was updated successfully, but these errors were encountered:

sculpt0r · 2020-12-16T13:44:21Z

Based on browser console - null is at line: https://github.com/ckeditor/ckeditor4/blob/major/core/creators/themedui.js#L458 (so, exactly as @Dumluregn said).
editor.ui is an object, but the result of space method is null.

My current status:

bug appears only for classic editor (so default one).
It happened only if the initial ckeditor element is hidden. If it's not - then both classic and inline editor types are fine.

Dumluregn · 2020-12-16T16:04:50Z

It happened only if the initial ckeditor element is hidden

It makes sense and explains why it fails in the frameworks - they usually do some magic during the component initialisation which often happens before the component is actually rendered.

sculpt0r · 2020-12-22T09:07:05Z

To be precise, in angular, the element is not hidden on not visible, but physically it's not in the document structure - that's why space( 'top' ) returns null. In the end it ends up with CKEDITOR.document.getById();

sculpt0r · 2020-12-23T08:38:29Z

Alright!

Note: Below angular sample is targeting editorUrl as localhost. Remove it to use default CDN editor.

After analyzing the test case from angular: https://stackblitz.com/edit/angular-issue-4390

I was able to create the same environment in plain CKEditor4: https://stackblitz.com/edit/js-yndfve

DOM structure during editor creation in angular (with hidden editor element inside p-dialog) looks like this:

textarea element is created
textarea element is placed as children for <ckeditor> element
<ckeditor> is child for p-dialog which will be invisible
textarea element has parent => <ckeditor>
<ckeditor> has no parent => angular magic that hide content under p-dialog
textarea element is used as reference element when calling CKEDITOR.replace

Potentially I even have some solution idea which targets ui.space() implementation.

sculpt0r · 2020-12-23T10:56:11Z

Fast fix approach in ui.space() method:

var id = '#' + this.spaceId( name );
var spaceElem = this.editor.container.findOne( id );

return spaceElem;

So we are looking for space elements inside the editor container - no in the entire document as before.

However...
I've got another problem with content iframe:

We have iframe element that contains editor data. It has full DOM tree structure, so e.g. html, body elements.
Our data is inside body.

Whenever unhide element with p-dialog, body element inside iframe is empty and contains only some ~~angular~~ markers:
<body data-new-gr-c-s-check-loaded="14.990.0" data-gr-ext-installed=""></body>

The same happens when the editor is initialized properly, then I hide it with p-dialog and show it again...

So there is no editor data...

Seems that p-dialog is a third party library for angular: https://primefaces.org/primeng/showcase/#/dialog

Dumluregn · 2020-12-23T12:21:18Z

So there is no editor data...

Do you mean that the editor data is erased when p-dialog element is shown?

Since this issue was also reproducible without p-dialog element (during running editor component tests in Karma), I think it is worth to try to fix it even if the originally reported issue in ckeditor4-angular will still occur (since it will be a problem with p-dialog now and not ckeditor), but before creating new tickets let's try to do as good as we can with this one and we can create follow-ups during the reviews.

Previously space elements were searched in the entire document. During editor container is safer scope for this: - we are expecting 'space' elements inside editor container anyway - #4390 - there could be situations when document is not available

sculpt0r · 2020-12-23T12:35:27Z

Do you mean that the editor data is erased when p-dialog element is shown?

Yes. Also, data bindings are gone.

I create two editors bound to data with https://ckeditor.com/docs/ckeditor4/latest/guide/dev_angular.html#integration-with-ngmodel

After hide & show the first one - I update data in the second one. The first editor shows no changes.

sculpt0r · 2020-12-28T10:08:03Z

Whenever unhide element with p-dialog, body element inside iframe is empty and contains only some angular markers:

Iframe reloading is caused by reattaching element. Angular use it, but it's more like expected behaviour...

I tried set data manually and with onload event - but I'm crashing on

Uncaught TypeError: Cannot read property 'getSelection' of undefined while setData is invoked. So more references are broken inside.

Previously space elements were searched in the entire document. During editor container is safer scope for this: - we are expecting 'space' elements inside editor container anyway - #4390 - there could be situations when document is not available

sculpt0r · 2020-12-31T09:06:40Z

After research and a talk with @f1ames we decide to split this issue into two separate features:

Detect detached element and wait with editor initialization until this element will be attached again. That should solve this particular issue (searching element when there is no document: "TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4390 (comment) & "TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4390 (comment) ). Also, this introduces a kind of lazyloading for CKEditor. Feature request: Prevent editor creation on detached element #4461
Allow CKEditor works in a detached state. The main problem happens when editor has attached again (with default 'wysiwyg' mode - base on iframe). It causes iframe reloading. Since src is empty - we end with an empty body in this iframe. Recreating the original body with all bindings is much more complicated, mainly due to on( 'load' ) binding. Feature request: Support editor functions after reattach to DOM #4462

sculpt0r · 2020-12-31T10:47:07Z

Summary:

Original issue is caused by editor.ui.space method:

ckeditor4/core/ui.js

Lines 123 to 125 in 1aa2119

    
           space: function( name ) { 
        
           	return CKEDITOR.document.getById( this.spaceId( name ) ); 
        
           },

then

ckeditor4/core/dom/document.js

Lines 148 to 151 in 1aa2119

    
           getById: function( elementId ) { 
        
           	var $ = this.$.getElementById( elementId ); 
        
           	return $ ? new CKEDITOR.dom.element( $ ) : null; 
        
           },

Since everything is detached - there is no proper element, so null is returned.

There is no verification whenever space was correctly found, this line gives an error:

ckeditor4/core/creators/themedui.js

Line 458 in 5380706

topHtml && editor.ui.space( 'top' ).unselectable();

Even after fix on editor.ui.space: there is another fix on selection to make:
74eb1de
Finally there is lot's of trouble with iframe reconstruction. Each time, editor is attached to DOM, browser tries to reload it. We have an empty src attribute, so it's impossible.

Manually recreation involves dealing with different setTimeouts while binding to load event and maintaining other events binding.

sculpt0r · 2021-01-04T08:41:09Z

I found a related issue: ckeditor/ckeditor4-react#109

So it's no longer only a detached state issue...

sculpt0r · 2021-05-26T12:17:07Z

Since we finished working on #4463 and #4601 - there is a time to verify our work with this root issue :)

Dumluregn · 2021-05-26T14:03:57Z

Just a friendly reminder for anyone trying to test the features in integrations - easy way of using the latest CKE4 major version is nightly build: https://nightly.ckeditor.com/latest/standard/ckeditor/ckeditor.js.

sculpt0r · 2021-05-27T10:49:15Z

I've pass editorUrl='https://nightly.ckeditor.com/latest/standard/ckeditor/ckeditor.js' to components in https://stackblitz.com/edit/angular-issue-4390 and delayIfDetached=true in config and there are no errors. Nor when the editor is hidden at the beginning or toggled. So... sounds good 🎉 👍

However... Inside #4390 (comment)

Yes. Also, data bindings are gone.

So I'll investigate it now.

sculpt0r · 2021-05-27T10:51:05Z

When the editor is created with delay, ngModel seems to have no effect...
https://github.com/ckeditor/ckeditor4-angular/blob/a6be961ec82422925c998c39832968ee1615cbae/src/ckeditor/ckeditor.component.ts#L302-L304 assumes we get editor instance, but that doesn't have to be true with delayed creation.

I've updated ckeditor/ckeditor4-angular#190 description so that we should use delayIfDetached_callback to properly create and initialize the editor.

sculpt0r · 2021-05-27T11:43:27Z

Partially solvable with current ckeditor4 major, but for full fix: blocked by ckeditor/ckeditor4-angular#190

Dumluregn · 2021-05-27T15:08:43Z

We have a root issue reported in Angular: ckeditor/ckeditor4-angular#114 and the CKE4 upstream is fixed. So I'd say this issue is solved, not blocked 🤔 WDYT @sculpt0r?

sculpt0r · 2021-05-28T20:31:55Z

@Dumluregn sounds reasonable :)

I'm closing it according to: #4463 & #4601

ezintz · 2021-06-25T09:34:03Z

Is there a chance to get this released as 4.16.2? We experience this issue quite often using the official Angular module for our application, so it would be nice to get rid of it (:

Dumluregn · 2021-07-14T09:44:54Z

Hello, unfortunately this is quite a big new feature and as such is going to be released as 4.17.0. If you want to test this feature earlier, you can use the nightly build temporarily: https://nightly.ckeditor.com/latest/standard/ckeditor/ckeditor.js (you can replace standard with e.g. full).

ezintz · 2021-10-11T20:09:56Z

Hello, thanks for your answer! I could see that the milestones for 4.17 are completed. Can we support somehow to get this new feature rather sooner than later?

sculpt0r · 2021-10-14T04:50:39Z

Hi @ezintz
Changes are already merged to major branch, however, we also have a few other things there. You may try to use it, but please notice, that until the release it may be unstable. We will release 4.17.0 as soon as we will be sure, that everything is working fine with all changes. I can just ask you for the patient. We don't want to release fastly one fix and broke something else. Since CKE4 is a huge codebase - we always need to pay attention to all of our features.

Also, you can try to apply changes to your own CKE4 source code(see: #4390 (comment)). But it will be more convenient to wait for the official realease.

ezintz · 2021-10-17T00:29:24Z

Hi @sculpt0r, thanks for your answer! I am glad and happy that you want to have a stable and working version released - I really appreciate your work! 🙂 We just keep having this error in our logs and sometimes the users are blocked, so we are willing to help and try to contribute 😉, if there is a way. I may try the nightly builds with our application already, thank you.

Thanks again for all your work!

Imaginativeone · 2022-11-29T16:58:37Z

I'm running into this error while using Vue 2. Which details do you need from me to fully describe the problem?

Dumluregn added type:task Any other issue (refactoring, typo fix, etc). status:confirmed An issue confirmed by the development team. size:M labels Nov 20, 2020

Dumluregn mentioned this issue Nov 23, 2020

Expose API notifying about loaded CKEDITOR namespace ckeditor/ckeditor4-angular#149

Merged

sculpt0r self-assigned this Dec 16, 2020

sculpt0r mentioned this issue Dec 28, 2020

"TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4454

Closed

2 tasks

This was referenced Dec 31, 2020

Prevent editor creation on detached element #4461

Closed

Support editor functions after reattach to DOM #4462

Closed

sculpt0r mentioned this issue Jan 4, 2021

CKEditor loses track of content when parent component key changes ckeditor/ckeditor4-react#109

Closed

Dumluregn mentioned this issue Jan 4, 2021

CKEditor 4 drop downs in ExtJs 6 Modern Dialog cause editor to loose content #4434

Closed

f1ames added size:External status:blocked An issue which development is blocked by another issue (internal or external one). and removed size:M labels Jan 18, 2021

Dumluregn mentioned this issue Feb 23, 2021

Add tests for the "onNamespaceLoaded" event ckeditor/ckeditor4-angular#172

Open

Dumluregn mentioned this issue May 13, 2021

Cannot read property 'unselectable' of null ckeditor/ckeditor4-angular#114

Closed

sculpt0r removed the status:blocked An issue which development is blocked by another issue (internal or external one). label May 26, 2021

sculpt0r added the status:blocked An issue which development is blocked by another issue (internal or external one). label May 27, 2021

sculpt0r closed this as completed May 28, 2021

sculpt0r removed the status:blocked An issue which development is blocked by another issue (internal or external one). label May 28, 2021

Comandeer mentioned this issue Apr 19, 2023

Null reference error while calling unslectable method #5460

Closed

oliverfoster mentioned this issue Feb 20, 2024

CK Editor not loading correctly adaptlearning/adapt_authoring#2751

Closed

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"TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4390

"TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4390

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Imaginativeone commented Nov 29, 2022

"TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4390

"TypeError: Cannot read property 'unselectable' of null" thrown when working with CKEditor in integrations #4390

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Dumluregn commented Nov 20, 2020

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