Implement PlateController

.changeset/late-bags-mix.md

@@ -0,0 +1,20 @@
+---
+"@udecode/plate-core": minor
+---
+
+- Introduce `PlateController` as a way of accessing the active editor from an ancestor or sibling of `Plate` (see [Accessing the Editor](https://platejs.org/docs/accessing-editor#from-a-sibling-or-ancestor-of-plate)).
+- Add `primary` prop to `Plate` (default true)
+- Add `isFallback` to `editor` instance (default false)
+- The following hooks now throw a runtime error when used outside of either a `Plate` or `PlateController`, and accept a `debugHookName` option to customize this error message:
+  - `useIncrementVersion`
+  - `useRedecorate`
+  - `useReplaceEditor`
+  - `useEditorMounted` (new)
+  - `useEditorReadOnly`
+  - `useEditorRef`
+  - `useEdtiorSelection`
+  - `useEditorSelector`
+  - `useEditorState`
+  - `useEditorVersion`
+  - `useSelectionVersion`
+- Change the default `id` of a `Plate` editor from `'plate'` to a random value generated with `nanoid/non-secure`

apps/www/content/docs/accessing-editor.mdx

@@ -75,7 +75,7 @@ Use the **`useEditorRef`**, **`useEditorSelector`** or **`useEditorState`** hook
 
 You can call these hooks from any React component that is rendered as a descendant of the **`Plate`** component, including [Plugin Components](/docs/plugin-components).
 
-```tsx
+```tsx showLineNumbers {2}
 const Toolbar = () => {
   const boldActive = useEditorSelector((editor) => isMarkActive(editor, MARK_BOLD), []);
   // ...
@@ -136,88 +136,72 @@ export default () => (
 ```
 
 <Callout className="my-4">
-  **If **`editor`** is modified by reference, why include it in dependency
+  **If `editor` is modified by reference, why include it in dependency
   lists?**
   <br />
   Good question! Even though **`editor`** is usually modified by reference,
   there are some situations in which it's replaced with a fresh instance, such
   as when the editor is reset.
 </Callout>
 
-## From an Ancestor
+## From a Sibling or Ancestor of Plate
 
-If you need to access the **`editor`** instance from an ancestor of **`PlateContent`**, wrapping the relevant components in a **`Plate`** is the preferred solution. If this is not an option, you can instead use the **`editorRef`** prop to pass a reference to the **`editor`** instance up the React component tree to where it is needed.
+If you need to access the **`editor`** outside of the **`Plate`** component, or if you're working with multiple editors and want to access whichever editor is currently active, you can use a **`PlateController`** component. **`PlateController`** is an optional component that can be rendered as an ancestor of one or more **`Plate`** components. For example, you can render a **`PlateController`** at the root of your app.
 
-The **`editorRef`** prop can be used with **`useRef`**, **`useState`**, or a custom ref callback. Regardless of which you use, you'll need to handle the case where **`editor`** is null. This happens when the editor hasn't had a chance to render yet or has unmounted.
+The **`PlateController`** will keep track of which editor is currently active. By default, the first mounted editor inside the **`PlateController`** will be used as the active editor (this can be disabled for individual editors by passing **`primary={false}`** to the **`Plate`** component). After that, every time an editor is focused, that editor becomes active. An editor remains active until another editor is focused or the active editor unmounts.
 
-### With a Ref Object
+Inside a **`PlateController`**, hooks like **`useEditorRef`** and **`useEditorSelector`** will return or operate on the currently active editor. If no editor is active, these hooks may return a fallback editor. This can happen under the following circumstances:
 
-```tsx showLineNumbers {2,21}
-const App = () => {
-  const editorRef = useRef<PlateEditor | null>(null);
-
-  const handleSomeEvent = useCallback(() => {
-    // editor has type PlateEditor | null
-    const editor = editorRef.current;
+- When no **`Plate`** component is mounted inside the **`PlateController`**
+- When all mounted **`Plate`** components are marked as non-primary
+- Temporarily while **`PlateContent`** is in the process of mounting
 
-    if (editor) {
-      // Do something with editor
-    }
-  }, []);
+The fallback editor is designed to ensure that code querying the **`editor`** produces sensible default values, the same as if they had been given an empty editor with no plugins. The fallback editor cannot be mutated, and will throw a runtime error if any state-changing operations are applied to it. To check if your component is accessing a real editor or a fallback editor, use the **`useEditorMounted`** hook (which returns false for a fallback editor), or check **`editor.isFallback`**.
 
-  // Pass editorRef and handleSomeEvent down to where they're needed
+```tsx showLineNumbers {2-3,9,19}
+const Toolbar = () => {
+  const editor = useEditorState(); // Returns the active editor (or a fallback editor)
+  const isMounted = useEditorMounted(); // Returns false if no editor is mounted
   // ...
 };
 
-const Editor = ({
-  editorRef,
-}: {
-  editorRef: MutableRefObject<PlateEditor | null>;
-}) => (
-  <Plate editorRef={editorRef}>
-    <PlateContent />
-  </Plate>
-);
+const App = () => {
+  return (
+    <PlateController>
+      <Toolbar />
+
+      <Plate>
+        <PlateContent />
+      </Plate>
+
+      <Plate>
+        <PlateContent />
+      </Plate>
+    </PlateController>
+  );
+};
 ```
 
-### With State
+## From the Parent of Plate
 
-If you want your ancestor component to re-render when the editor content changes, you may want to use **`useState`** to store your **`editor`** instance. Since the **`editorRef`** callback is only called once when the editor first mounts, you'll also need to manually trigger a re-render by updating a counter whenever the **`onChange`** handler of **`Plate`** is called.
+The **`editorRef`** prop is an older, alternative way of accessing the **`editor`** outside of **`Plate`**, and works best in cases where the **`editor`** instance must be accessed in the **`Plate`** component's parent. In all other cases, **`PlateController`** is the preferred solution (see above).
 
-Using **`editorRef`** with **`useState`** without a counter is equivalent to using **`useEditorRef`** instead of **`useEditorState`** (the difference is discussed above). Most of the time, if you don't need the ancestor component to re-render on every change, you should be using **`useRef`** instead.
+The ref can be created with  **`useRef`**, the setter function of **`useState`**, or a custom ref callback. It is populated with the **`editor`** instance when **`Plate`** mounts, and **`null`** when **`Plate`** unmounts. Since the **`editor`** is unavailable during the first render, and may become unavailable if the **`Plate`** component unmounts, you must handle the case where **`editor`** is **`null`**.
 
-```tsx showLineNumbers {2-3,34-35}
+```tsx showLineNumbers {2,13}
 const App = () => {
-  const [editor, setEditor] = useState<PlateEditor | null>(null);
-  const [, handleUpdateEditor] = useReducer((x) => x + 1, 0);
-
-  // Pass editor, setEditor and handleUpdateEditor down to where they're needed
-  // ...
-};
+  const editorRef = useRef<PlateEditor | null>(null);
 
-const EditorPreview = ({ editor }: { editor: PlateEditor | null }) => {
-  // html has type string | null
-  const html = useMemo(
-    () =>
-      editor &&
-      serializeHtml(editor, {
-        nodes: editor.children,
-      }),
-    [editor, editor?.children]
-  );
+  const handleSomeEvent = useCallback(() => {
+    const editor = editorRef.current;
 
-  if (!html) return null;
-  return <div dangerouslySetInnerHTML={{ __html: html }} />;
-};
+    // Handle the case where editor is null
+    if (editor) {
+      // Do something with editor
+    }
+  }, []);
 
-const Editor = ({
-  setEditor,
-  handleUpdateEditor,
-}: {
-  setEditor: (editor: PlateEditor | null) => void;
-  handleUpdateEditor: () => void;
-}) => (
-  <Plate editorRef={setEditor} onChange={handleUpdateEditor}>
+  <Plate editorRef={editorRef}>
     <PlateContent />
   </Plate>
 );

apps/www/content/docs/api/core.mdx

@@ -316,7 +316,7 @@ The value of the element as a TElement.
 Get the Slate editor reference without re-rendering.
 
 - Does not re-render on editor change.
-- Should be used inside `Plate`.
+- Must be used inside `Plate` or `PlateController` (see [Accessing the Editor](/docs/accessing-editor/)).
 - Note the reference does not change when the editor changes.
 
 <APIParameters>
@@ -336,7 +336,7 @@ Subscribe to a specific property of the editor.
 
 - Calls the selector function on editor change.
 - Re-renders when the result of the selector changes.
-- Should be used inside `Plate`.
+- Must be used inside `Plate` or `PlateController` (see [Accessing the Editor](/docs/accessing-editor/)).
 
 <APIParameters>
   <APIItem name="selector" type="(editor: PlateEditor<V>, prev?: T) => T">
@@ -370,7 +370,7 @@ Get the Slate editor reference with re-rendering.
 
 - Re-renders on editor change.
 - Supports nested editors.
-- Should be used inside `Plate`.
+- Must be used inside `Plate` or `PlateController` (see [Accessing the Editor](/docs/accessing-editor/)).
 - Note the reference does not change when the editor changes.
 - If performance is a concern, `useEditorSelector` should be used instead.
 
@@ -400,6 +400,21 @@ The `readOnly` state of the editor.
 
 </APIReturns>
 
+### useEditorMounted
+
+Get the editor's `isMounted` state.
+
+<APIParameters>
+  <APIItem name="id" type="PlateId" optional>
+    The ID of the plate editor.
+  </APIItem>
+</APIParameters>
+<APIReturns>
+
+The `isMounted` state of the editor.
+
+</APIReturns>
+
 ### useEditorSelection
 
 Get the editor's selection. Memoized so it does not re-render if the range is the same.

apps/www/content/docs/api/core/plate.mdx

@@ -86,6 +86,13 @@ Controlled callback called when the editor state changes.
 
 Plate plugins. See [Plugin](/docs/plugin) guide.
 
+</APIItem>
+<APIItem name="primary" type="boolean" optional>
+
+Controls whether the editor is considered active by default when used with a PlateController. See [Accessing the Editor](/docs/accessing-editor#from-a-sibling-or-ancestor-of-plate).
+
+- **Default:** **`true`**
+
 </APIItem>
 <APIItem name="value" type="Value" optional>
 

packages/core/package.json

@@ -46,9 +46,11 @@
     "clsx": "^1.2.1",
     "is-hotkey": "^0.2.0",
     "jotai": "^2.6.0",
-    "jotai-x": "^1.1.0",
+    "jotai-optics": "0.3.1",
+    "jotai-x": "^1.2.1",
     "lodash": "^4.17.21",
     "nanoid": "^3.3.6",
+    "optics-ts": "2.4.1",
     "react-hotkeys-hook": "^4.4.1",
     "use-deep-compare": "^1.1.0",
     "zustand": "^4.4.7",

packages/core/src/components/Plate.spec.tsx

@@ -6,7 +6,7 @@ import {
   usePlateSelectors,
 } from '@udecode/plate-common';
 
-import { PLATE_SCOPE } from '../stores/index';
+import { PlateController, usePlateEditorStore } from '../stores';
 import { Plate } from './Plate';
 
 describe('Plate', () => {
@@ -27,24 +27,36 @@ describe('Plate', () => {
     });
     describe('when editor is not defined', () => {
       it('should be default', async () => {
-        const wrapper = ({ children }: any) => <Plate>{children}</Plate>;
+        const wrapper = ({ children }: any) => (
+          <Plate id="test1">
+            <Plate id="test2">{children}</Plate>
+          </Plate>
+        );
+
         const { result } = renderHook(() => useEditorRef(), {
           wrapper,
         });
 
-        expect(result.current.id).toBe(PLATE_SCOPE.toString());
+        expect(result.current.id).toBe('test2');
       });
     });
     describe('when id is defined', () => {
       it('should be id', async () => {
         const wrapper = ({ children }: any) => (
-          <Plate id="test">{children}</Plate>
+          <Plate id="test1">
+            <Plate id="test2">{children}</Plate>
+          </Plate>
         );
-        const { result } = renderHook(() => useEditorRef('test'), {
+
+        const { result: result1 } = renderHook(() => useEditorRef('test1'), {
+          wrapper,
+        });
+        const { result: result2 } = renderHook(() => useEditorRef('test2'), {
           wrapper,
         });
 
-        expect(result.current.id).toBe('test');
+        expect(result1.current.id).toBe('test1');
+        expect(result2.current.id).toBe('test2');
       });
     });
   });
@@ -224,19 +236,75 @@ describe('Plate', () => {
         expect(result.current).toBe('test');
       });
     });
+  });
 
-    describe('when Plate with id > Plate without id', () => {
-      it('should be that id', () => {
+  describe('usePlateEditorStore', () => {
+    const getStore = (wrapper: any) =>
+      renderHook(() => usePlateEditorStore(), { wrapper }).result.current;
+
+    const getId = (wrapper: any) =>
+      renderHook(() => usePlateSelectors().id(), { wrapper }).result.current;
+
+    const getIsFallback = (wrapper: any) =>
+      renderHook(() => useEditorRef().isFallback, { wrapper }).result.current;
+
+    describe('when Plate exists', () => {
+      it('returns the store', () => {
         const wrapper = ({ children }: any) => (
-          <Plate id="test">
-            <Plate>{children}</Plate>
-          </Plate>
+          <Plate id="test">{children}</Plate>
         );
-        const { result } = renderHook(() => usePlateSelectors().id(), {
-          wrapper,
+
+        expect(getStore(wrapper)).toBeDefined();
+        expect(getId(wrapper)).toBe('test');
+        expect(getIsFallback(wrapper)).toBe(false);
+      });
+    });
+
+    describe('when Plate does not exist', () => {
+      describe('when PlateController exists', () => {
+        describe('when PlateController returns a store', () => {
+          it('returns the store', () => {
+            const EXPECTED_STORE = 'expected store' as any;
+
+            const wrapper = ({ children }: any) => (
+              <PlateController
+                editorStores={{
+                  test: EXPECTED_STORE,
+                }}
+                activeId="test"
+              >
+                {children}
+              </PlateController>
+            );
+
+            expect(getStore(wrapper)).toBe(EXPECTED_STORE);
+          });
         });
 
-        expect(result.current).toBe(PLATE_SCOPE);
+        describe('when PlateController returns null', () => {
+          it('returns the fallback store', () => {
+            const wrapper = ({ children }: any) => (
+              <PlateController
+                editorStores={{
+                  test: null,
+                }}
+                activeId="test"
+              >
+                {children}
+              </PlateController>
+            );
+
+            expect(getStore(wrapper)).toBeDefined();
+            expect(getIsFallback(wrapper)).toBe(true);
+          });
+        });
+      });
+
+      describe('when PlateController does not exist', () => {
+        it('throws an error', () => {
+          const wrapper = ({ children }: any) => <>{children}</>;
+          expect(() => getStore(wrapper)).toThrowError();
+        });
       });
     });
   });