See real time updates when you change title in sidebar

README.md

@@ -141,9 +141,30 @@ If you wish to make the editing experience faster you can register for ```onSave
 
 #### Enable Show changes while editing
 
-You will need to subscribe to an ```onEditChange``` event that will send blocks or metadata changes
+You will need to subscribe to an ```onEditChange``` event that will send blocks or metadata changes. 
 
-TODO: not implemented yet. 
+The `onEditChange` method listens for changes in the Hydra and triggers a callback with updated data or the initial data if no update is available.
+The 'data' object follows the same format as you get from the [ploneClient](https://6.docs.plone.org/volto/client/quick-start.html?highlight=data#query-or-mutation-options-factories).
+
+`onEditChange` takes following args:
+| Args         | Description |
+| :-----------:| :-------|
+| *initialData*| The initial data to fall back on if no updated data is received. |
+| *callback*   | A function to call with the updated data when a change is detected. |
+
+Usage:
+```js
+// the initial data (from ploneClient)
+const initialData = data;
+
+// Define the callback function
+function handleEditChange(updatedData) {
+  console.log('Updated data:', updatedData);
+}
+
+// Set up the onEditChange listener
+onEditChange(initialData, handleEditChange);
+```
 
 #### Enable Managing Blocks directly on your frontend
 

hydra.js

@@ -29,7 +29,19 @@ class Bridge {
       }
     });
   }
-
+  onEditChange(initialData, callback) {
+    window.addEventListener('message', (event) => {
+      if (event.origin === this.adminOrigin) {
+        if (event.data.type === 'FORM') {
+          if (event.data.data) {
+            callback(event.data.data);
+          } else {
+            callback(initialData);
+          }
+        }
+      }
+    });
+  }
   async get_token() {
     if (this.token !== null) {
       return this.token;
@@ -130,3 +142,13 @@ export async function getToken() {
   }
   return '';
 }
+/**
+ * Enable the frontend to listen for changes in the admin and call the callback with updated data
+ * @param {*} initialData
+ * @param {*} callback
+ */
+export function onEditChange(initialData, callback) {
+  if (bridgeInstance) {
+    bridgeInstance.onEditChange(initialData, callback);
+  }
+}

packages/volto-hydra/src/components/Iframe/View.jsx

@@ -5,26 +5,22 @@ import Cookies from 'js-cookie';
 import './styles.css';
 
 const Iframe = () => {
-  const [url, setUrl] = useState('');
-
-  const [src, setSrc] = useState('');
   const history = useHistory();
   const token = useSelector((state) => state.userSession.token);
-
+  const form = useSelector((state) => state.form.global);
   const getDefualtUrlFromEnv = () =>
     process.env['RAZZLE_DEFAULT_IFRAME_URL'] ||
     (typeof window !== 'undefined' && window.env['RAZZLE_DEFAULT_IFRAME_URL']);
 
-  useEffect(() => {
-    const defaultUrl = getDefualtUrlFromEnv() || 'http://localhost:3002'; // fallback if env is not set
-    const savedUrl = Cookies.get('iframe_url');
-    const initialUrl = savedUrl
-      ? `${savedUrl}${window.location.pathname.replace('/edit', '')}`
-      : `${defaultUrl}${window.location.pathname.replace('/edit', '')}`;
-
-    setUrl(initialUrl);
-    setSrc(initialUrl);
+  const defaultUrl = getDefualtUrlFromEnv() || 'http://localhost:3002'; // fallback if env is not set
+  const savedUrl = Cookies.get('iframe_url');
+  const initialUrl = savedUrl
+    ? `${savedUrl}${history.location.pathname.replace('/edit', '')}`
+    : `${defaultUrl}${history.location.pathname.replace('/edit', '')}`;
+  const [url, setUrl] = useState(initialUrl);
+  const [src, setSrc] = useState(initialUrl);
 
+  useEffect(() => {
     // Listen for messages from the iframe
     const initialUrlOrigin = new URL(initialUrl).origin;
     window.addEventListener('message', (event) => {
@@ -51,15 +47,25 @@ const Iframe = () => {
     });
   }, [token]);
 
+  useEffect(() => {
+    if (typeof window !== 'undefined') {
+      // Send the form data to the iframe
+      const origin = new URL(initialUrl).origin;
+      document
+        .getElementById('previewIframe')
+        .contentWindow.postMessage({ type: 'FORM', data: form }, origin);
+    }
+  }, [form]);
+
   const handleUrlChange = (event) => {
     setUrl(event.target.value);
   };
 
   const handleNavigateToUrl = (givenUrl = '') => {
     // Update adminUI URL with the new URL
     const formattedUrl = givenUrl ? new URL(givenUrl) : new URL(url);
-    const newUrl = formattedUrl.href;
-    setSrc(newUrl);
+    // const newUrl = formattedUrl.href;
+    // setSrc(newUrl);
     const newOrigin = formattedUrl.origin;
     Cookies.set('iframe_url', newOrigin, { expires: 7 });