Errors when trying to call some editor methods too quickly (synchronously)

[Piotrek Koszuliński]

Why CKEditor fails when I try to call some methods one after another?

editor.setData( someData );
// somewhere later...
editor.destroy();

The answer, unfortunately, isn't simple. Otherwise we'd have this fixed a long time ago. This is a mix of history, backwards compatibility, architectural limitations and lack of good solutions.

First thing to notice is that this is not only editor.setData's problem, because other editor's methods could malfunction too. Editor.getData, editor.destroy, editor.setReadOnly, etc. are not going to work if editor is not in the ready state. Furthermore, this problem concerns some other classes as well - e.g. CKEDITOR.editable.

Second thing to notice is that this problem occurs not only when editor isn't loaded yet, but also when switching between states and setting data (both operations can be asynchronous). This introduces more variables to the equation and could even make the state checks pretty ugly. Fortunately, we introduced editor.status and editable.status (although, we did this pretty recently), so currently this wouldn't be that bad.

Another architectural aspect that would have to be taken into consideration is how the code is decoupled. For instance, the editor.setData method only fires an event. If we started checking the editable's state inside this method we would create a tight relations and could break some existing implementations.

Backwards compatibility is important for one more reason - we can make backward incompatible changes, but we must do them in a smart way. For instance, once it's done it should be final - we can't ship some other solution in the next major release if this one turns out to be unsatisfactory. This rises the stake pretty high.

The last thing, and actually the most unfortunate, is that throwing errors is not that good solution. It may tell you that you're doing something wrong, but it won't tell you when you can do it.

try {
	editor.setData( ... );
} catch ( err ) {
	if ( err instanceof CKEDITOR.editorNotReadyError ) {
		// apparently, it wasn't the right moment
		// ... and what now? Ok, let's wait for some imaginary "ready" event
		// (which doesn't exist right now):
		editor.once( 'ready', function() {
			editor.setData( ... );
			// ... actually, this could throw again if some other editor#ready
			// listener called setData too and haven't cancel the event.
		} );
	} else {
		throw err;
	}
}

Isn't it ugly? I think it's a terrible developer experience. A more useful approach would to be cache method calls and execute them when the editor reaches the correct state. But this would mean that for instance editor.destroy, which is currently a synchronous method, would become an asynchronous one because it can't be executed while editor is not ready. Moreover, to make all this possible to implement we would need to do serious changes not only in the API, but in the editor internals as well. Even the highly unsatisfactory solution with throwing errors requires significant effort to and may lead to ugly compatibility issues.

To sum up. I don't want say that fixing this in CKEditor 4.x is impossible, but for now we didn't have enough resources and well... courage, to attempt that. I would also risk a statement that it's late in CKEditor 4.x for such changes. But most importantly, we are aware of these problems and will definitely ​design CKEditor 5's API differently.

[Piotrek Koszuliński]

I wrote this ticket as an answer to ​http://junglecoder.com/blog/CKEditorSetDataNotWorking

[Piotrek Koszuliński]

Nice. I wrote a duplicate of my own ticket - #11502 :D. I'll copy the post there.