Manipulate innerText of a CKEditor ViewElement - ckeditor5

Question

I am creating a little custom plugin for the CKEditor5 for the #neoscms.
Neos is using the #ckeditor5 but with a custom view.
The plugin is more or less a placeholder plugin. The user can configure a data-source with a key value store for items (identifier and labels). The dropdown in the CKEditor is filled with the items and when the user selects an item from the dropdown, it creates a placeholder element that should end in a span element with some data-attributes.
The main idea was to have an empty element and just data-attributes to identify the element and being able to assign live data. But it turns out that the live data thing is tricky. When I manipulate the span with an extra JS snippet on the Website, the CKEditor cannot handle this.
Is it possible to manipulate a view element in the DOM and still have a working Editor?
The Plugin works fine if I just add inner Text in the downCasting and don't replace something. But the live data would be nice.
Neos Backend with a element
Maybe that code gives an idea of the package.
It is not ready yet as this is more or less the main feature ;)
import {Plugin, toWidget, viewToModelPositionOutsideModelElement, Widget,} from "ckeditor5-exports";
import PlaceholderCommand from "./placeHolderCommand";
export default class PlaceholderEditing extends Plugin {
static get requires() {
return [Widget];
}
init() {
this._defineSchema();
this._defineConverters();
this.editor.commands.add(
"placeholder",
new PlaceholderCommand(this.editor)
);
this.editor.editing.mapper.on(
"viewToModelPosition",
viewToModelPositionOutsideModelElement(this.editor.model, (viewElement) =>
viewElement.hasClass("internezzo-placeholder")
)
);
this.editor.config.define("placeholderProps", {
types: ["name", "node", "nodePath"],
});
this.editor.config.define("placeholderBrackets", {
open: "[",
close: "]",
});
}
_defineSchema() {
const schema = this.editor.model.schema;
schema.register("placeholder", {
allowWhere: "$text",
isInline: true,
isObject: true,
allowAttributes: [
"name",
"node",
"nodePath",
"data-placeholder-identifier",
"data-node-identifier",
"data-node-path",
],
});
}
_defineConverters() {
const conversion = this.editor.conversion;
const config = this.editor.config;
conversion.for("upcast").elementToElement({
view: {
name: "span",
classes: ["foobar-placeholder"],
},
model: (viewElement, writer) => {
const name = viewElement.getAttribute('data-placeholder-identifier');
const node = viewElement.getAttribute('data-node-identifier');
const nodePath = viewElement.getAttribute('data-node-path');
const modelWriter = writer.writer || writer;
return modelWriter.createElement("placeholder", {name, node, nodePath, editable: false});
},
});
conversion.for("editingDowncast").elementToElement({
model: "placeholder",
view: (modelItem, writer) => {
const viewWriter = writer.writer || writer;
const widgetElement = createPlaceholderView(modelItem, viewWriter);
return toWidget(widgetElement, viewWriter);
},
});
conversion.for("dataDowncast").elementToElement({
model: "placeholder",
view: (modelItem, writer) => {
const viewWriter = writer.writer || writer;
return createPlaceholderView(modelItem, viewWriter);
},
});
// Helper method for downcast converters.
function createPlaceholderView(modelItem, viewWriter) {
const name = modelItem.getAttribute("name");
const node = modelItem.getAttribute("node");
const nodePath = modelItem.getAttribute("nodePath");
const placeholderView = viewWriter.createContainerElement("span", {
class: "foobar-placeholder",
"data-placeholder-identifier": name,
"data-node-identifier": node,
"data-node-path": nodePath,
});
// Would be nice to remove that and have just empty spans that get dynamic data
let innerText = config.get("placeholderBrackets.open") + name;
innerText += config.get("placeholderBrackets.close");
viewWriter.insert(
viewWriter.createPositionAt(placeholderView, 0),
viewWriter.createText(innerText)
);
return placeholderView;
}
}
}
So, the extra JS snippet that is used by the website is searching for spans with the class foobar-placeholder and writes a value with live data into the span. That works in the frontend, of course, but the backend of the CMS that uses CKEditor has issues with the changing data.

Answer 1

I could not find a solution with docs of CKEditor, and maybe I misuse the API somehow, but I now found a working solution for me.
My website snippet is now communicating with the Plugin via Broadcast messages. And then I search for placeholder elements and check if I need to change an attribute.
const broadcastChannel = new BroadcastChannel('placeholder:changeData');
broadcastChannel.postMessage({identifier: name, value});
And in the plugin
// Receive new values for placeholder via broadcast
const broadcastChannel = new BroadcastChannel('placeholder:changeData');
broadcastChannel.onmessage = (message) => {
const identifier = get('data.identifier', message);
const newValue = get('data.value', message);
this.editor.model.change( writer => {
if (identifier) {
this._replaceAttribute(writer, identifier, newValue);
}
});
};
Only downside now is that I need to reload the page, but already read that this is maybe cause by my element down casting and I change attributes.