POST

Get current content from the editor state using editorState.getCurrentContent() and save that to a variable.
Convert the current state to a string with these methods: JSON.stringify(convertToRaw(data));

GET

Display the data in a Draft.js Editor set to readOnly
Fetch the post from the server and then convert it to readable content with this.
const contentState = convertFromRaw(JSON.parse(el.content)); const editorState = EditorState.createWithContent(contentState);
Show it in an Editor like so:
<Editor editorState={editorState} readOnly={true}

GET（React Hooks）

useEffect(() => {
    postId && getPost(postId)
  }, [postId]);

  const [editorState, setEditorState] = useState(EditorState.createEmpty())
  useEffect(() => {
    if(postcontent) {
      const contentState = convertFromRaw(JSON.parse(postcontent));
      const newEditorState = EditorState.createWithContent(contentState, decorator);
      setEditorState(newEditorState);
    } else { 
      console.log("false")
    }
  }, [postcontent])