[Doc] Fix onSuccess callback signature for optimistic and undoable queries

docs/Actions.md

@@ -515,7 +515,8 @@ const ApproveButton = ({ record }) => {
         },
         {
 +           mutationMode: 'undoable',
-            onSuccess: ({ data }) => {
+-           onSuccess: ({ data }) => {
++           onSuccess: () => {
                 redirect('/comments');
 -               notify('Comment approved');
 +               notify('Comment approved', 'info', {}, true);
@@ -527,7 +528,7 @@ const ApproveButton = ({ record }) => {
 };
 ```
 
-As you can see in this example, you need to tweak the notification for undoable calls: passing `true` as fourth parameter of `notify` displays the 'Undo' button in the notification.
+As you can see in this example, you need to tweak the notification for undoable calls: passing `true` as fourth parameter of `notify` displays the 'Undo' button in the notification. Also, as side effects are executed immediately, they can't rely on the response beins passed to onSuccess.
 
 You can pass the `mutationMode` option parameter to specialized hooks, too. They all accept an optional last argument with side effects.
 
@@ -545,7 +546,7 @@ const ApproveButton = ({ record }) => {
         record,
         {
             mutationMode: 'undoable',
-            onSuccess: ({ data }) => {
+            onSuccess: () => {
                 redirect('/comments');
                 notify('Comment approved', 'info', {}, true);
             },

docs/CreateEdit.md

@@ -396,8 +396,8 @@ const PostEdit = props => {
     const refresh = useRefresh();
     const redirect = useRedirect();
 
-    const onSuccess = ({ data }) => {
-        notify(`Changes to post "${data.title}" saved`)
+    const onSuccess = () => {
+        notify(`Changes saved`)
         redirect('/posts');
         refresh();
     };
@@ -412,26 +412,53 @@ const PostEdit = props => {
 }
 ```
 
-The `onSuccess` function receives the response from the dataProvider call (`dataProvider.create()` or `dataProvider.update()`), which is the created/edited record (see [the dataProvider documentation for details](./DataProviders.md#response-format))
+By default, the `<Edit>` view runs updates in `mutationMode="undoable"`, which means that it calls the `onSuccess` side effects immediately, even before the `dataProvider` is called.
 
 The default `onSuccess` function is:
 
 ```jsx
 // for the <Create> component:
-({ data }) => {
+() => {
     notify('ra.notification.created', 'info', { smart_count: 1 });
     redirect('edit', basePath, data.id, data);
 }
 
 // for the <Edit> component: 
-({ data }) => {
+() => {
     notify('ra.notification.updated', 'info', { smart_count: 1 }, mutationMode === 'undoable');
     redirect('list', basePath, data.id, data);
 }
 ```
 
 To learn more about built-in side effect hooks like `useNotify`, `useRedirect` and `useRefresh`, check the [Querying the API documentation](./Actions.md#handling-side-effects-in-usedataprovider).
 
+**Tip**: When you use `mutationMode="pessimistic"`, the `onSuccess` function receives the response from the dataProvider call (`dataProvider.create()` or `dataProvider.update()`), which is the created/edited record (see [the dataProvider documentation for details](./DataProviders.md#response-format)). You can use that response in the success side effects: 
+
+```jsx
+import * as React from 'react';
+import { useNotify, useRefresh, useRedirect, Edit, SimpleForm } from 'react-admin';
+
+const PostEdit = props => {
+    const notify = useNotify();
+    const refresh = useRefresh();
+    const redirect = useRedirect();
+
+  const onSuccess = ({ data }) => {
+        notify(`Changes to post "${data.title}" saved`)
+        redirect('/posts');
+        refresh();
+    };
+
+    return (
+        <Edit onSuccess={onSuccess} mutationMode="pessimistic" {...props}>
+            <SimpleForm>
+                ...
+            </SimpleForm>
+        </Edit>
+    );
+}
+```
+
 **Tip**: When you set the `onSuccess` prop, the `successMessage` prop is ignored.
 
 **Tip**: If you want to have different success side effects based on the button clicked by the user (e.g. if the creation form displays two submit buttons, one to "save and redirect to the list", and another to "save and display an empty form"), you can set the `onSuccess` prop on the `<SaveButton>` component, too.