feat(content-docs): displayed_sidebar front matter

packages/docusaurus-plugin-content-docs/src/docFrontMatter.ts

@@ -30,6 +30,7 @@ const DocFrontMatterSchema = Joi.object<DocFrontMatter>({
   sidebar_label: Joi.string(),
   sidebar_position: Joi.number(),
   sidebar_class_name: Joi.string(),
+  displayed_sidebar: Joi.string().allow(null),
   tags: FrontMatterTagsSchema,
   pagination_label: Joi.string(),
   custom_edit_url: URISchema.allow('', null),

packages/docusaurus-plugin-content-docs/src/docs.ts

@@ -295,6 +295,7 @@ export function addDocNavigation(
     const navigation = sidebarsUtils.getDocNavigation(
       doc.unversionedId,
       doc.id,
+      doc.frontMatter.displayed_sidebar,
     );
 
     const toNavigationLinkByDocId = (

packages/docusaurus-plugin-content-docs/src/sidebars/__tests__/utils.test.ts

@@ -12,7 +12,6 @@ import {
   collectSidebarLinks,
   transformSidebarItems,
   collectSidebarsDocIds,
-  type SidebarNavigation,
   toDocNavigationLink,
   toNavigationLink,
 } from '../utils';
@@ -140,50 +139,50 @@ describe('createSidebarsUtils', () => {
   });
 
   test('getDocNavigation', async () => {
-    expect(getDocNavigation('doc1', 'doc1')).toEqual({
+    expect(getDocNavigation('doc1', 'doc1', undefined)).toEqual({
       sidebarName: 'sidebar1',
       previous: undefined,
       next: {
         type: 'doc',
         id: 'doc2',
       },
-    } as SidebarNavigation);
-    expect(getDocNavigation('doc2', 'doc2')).toEqual({
+    });
+    expect(getDocNavigation('doc2', 'doc2', undefined)).toEqual({
       sidebarName: 'sidebar1',
       previous: {
         type: 'doc',
         id: 'doc1',
       },
       next: undefined,
-    } as SidebarNavigation);
+    });
 
-    expect(getDocNavigation('doc3', 'doc3')).toEqual({
+    expect(getDocNavigation('doc3', 'doc3', undefined)).toEqual({
       sidebarName: 'sidebar2',
       previous: undefined,
       next: {
         type: 'doc',
         id: 'doc4',
       },
-    } as SidebarNavigation);
-    expect(getDocNavigation('doc4', 'doc4')).toEqual({
+    });
+    expect(getDocNavigation('doc4', 'doc4', undefined)).toEqual({
       sidebarName: 'sidebar2',
       previous: {
         type: 'doc',
         id: 'doc3',
         label: 'Doc 3',
       },
       next: undefined,
-    } as SidebarNavigation);
+    });
 
-    expect(getDocNavigation('doc5', 'doc5')).toMatchObject({
+    expect(getDocNavigation('doc5', 'doc5', undefined)).toMatchObject({
       sidebarName: 'sidebar3',
       previous: undefined,
       next: {
         type: 'category',
         label: 'S3 SubCategory',
       },
-    } as SidebarNavigation);
-    expect(getDocNavigation('doc6', 'doc6')).toMatchObject({
+    });
+    expect(getDocNavigation('doc6', 'doc6', undefined)).toMatchObject({
       sidebarName: 'sidebar3',
       previous: {
         type: 'category',
@@ -193,15 +192,30 @@ describe('createSidebarsUtils', () => {
         type: 'doc',
         id: 'doc7',
       },
-    } as SidebarNavigation);
-    expect(getDocNavigation('doc7', 'doc7')).toMatchObject({
+    });
+    expect(getDocNavigation('doc7', 'doc7', undefined)).toEqual({
       sidebarName: 'sidebar3',
       previous: {
         type: 'doc',
         id: 'doc6',
       },
       next: undefined,
-    } as SidebarNavigation);
+    });
+    expect(getDocNavigation('doc3', 'doc3', null)).toEqual({
+      sidebarName: undefined,
+      previous: undefined,
+      next: undefined,
+    });
+    expect(() =>
+      getDocNavigation('doc3', 'doc3', 'foo'),
+    ).toThrowErrorMatchingInlineSnapshot(
+      `"Doc with ID doc3 wants to display sidebar foo but a sidebar with this name doesn't exist"`,
+    );
+    expect(getDocNavigation('doc3', 'doc3', 'sidebar1')).toEqual({
+      sidebarName: 'sidebar1',
+      previous: undefined,
+      next: undefined,
+    });
   });
 
   test('getCategoryGeneratedIndexNavigation', async () => {
@@ -217,7 +231,7 @@ describe('createSidebarsUtils', () => {
         type: 'category',
         label: 'S3 SubSubCategory',
       },
-    } as SidebarNavigation);
+    });
 
     expect(
       getCategoryGeneratedIndexNavigation('/s3-subsubcategory-index-permalink'),
@@ -231,7 +245,7 @@ describe('createSidebarsUtils', () => {
         type: 'doc',
         id: 'doc6',
       },
-    } as SidebarNavigation);
+    });
   });
 
   test('getCategoryGeneratedIndexList', async () => {

packages/docusaurus-plugin-content-docs/src/sidebars/utils.ts

@@ -131,6 +131,7 @@ export type SidebarsUtils = {
   getDocNavigation: (
     unversionedId: string,
     versionedId: string,
+    displayedSidebar: string | null | undefined,
   ) => SidebarNavigation;
   getCategoryGeneratedIndexList: () => SidebarItemCategoryWithGeneratedIndex[];
   getCategoryGeneratedIndexNavigation: (
@@ -182,16 +183,25 @@ export function createSidebarsUtils(sidebars: Sidebars): SidebarsUtils {
   function getDocNavigation(
     unversionedId: string,
     versionedId: string,
+    displayedSidebar: string | null | undefined,
   ): SidebarNavigation {
     // TODO legacy id retro-compatibility!
     let docId = unversionedId;
-    let sidebarName = getSidebarNameByDocId(docId);
-    if (!sidebarName) {
+    let sidebarName =
+      displayedSidebar === undefined
+        ? getSidebarNameByDocId(docId)
+        : displayedSidebar;
+    if (sidebarName === undefined) {
       docId = versionedId;
       sidebarName = getSidebarNameByDocId(docId);
     }
 
     if (sidebarName) {
+      if (!sidebarNameToNavigationItems[sidebarName]) {
+        throw new Error(
+          `Doc with ID ${docId} wants to display sidebar ${sidebarName} but a sidebar with this name doesn't exist`,
+        );
+      }
       const navigationItems = sidebarNameToNavigationItems[sidebarName];
       const currentItemIndex = navigationItems.findIndex((item) => {
         if (item.type === 'doc') {
@@ -202,6 +212,9 @@ export function createSidebarsUtils(sidebars: Sidebars): SidebarsUtils {
         }
         return false;
       });
+      if (currentItemIndex === -1) {
+        return {sidebarName, next: undefined, previous: undefined};
+      }
 
       const {previous, next} = getElementsAround(
         navigationItems,

packages/docusaurus-plugin-content-docs/src/sidebars/validation.ts

@@ -22,6 +22,9 @@ import type {
 import {isCategoriesShorthand} from './utils';
 import type {CategoryMetadataFile} from './generator';
 
+// NOTE: we don't add any default values during validation on purpose!
+// Config types are exposed to users for typechecking and we use the same type in normalization
+
 const sidebarItemBaseSchema = Joi.object<SidebarItemBase>({
   className: Joi.string(),
   customProps: Joi.object().unknown(),

packages/docusaurus-plugin-content-docs/src/types.ts

@@ -66,6 +66,7 @@ export type DocFrontMatter = {
   sidebar_label?: string;
   sidebar_position?: number;
   sidebar_class_name?: string;
+  displayed_sidebar?: string | null;
   pagination_label?: string;
   custom_edit_url?: string | null;
   parse_number_prefixes?: boolean;

website/_dogfooding/_docs tests/doc-with-another-sidebar.md

@@ -0,0 +1,7 @@
+---
+displayed_sidebar: anotherSidebar
+---
+
+# Doc with another sidebar
+
+My link appears in a sidebar, but I want to display another sidebar...

website/_dogfooding/_docs tests/doc-without-sidebar.md

@@ -0,0 +1,7 @@
+---
+displayed_sidebar: null
+---
+
+# Doc without sidebar
+
+My link appears in a sidebar, but I don't want to display that...

website/_dogfooding/_docs tests/dummy.md

@@ -0,0 +1 @@
+# Just a dummy page

website/_dogfooding/docs-tests-sidebars.js

@@ -14,6 +14,8 @@ const sidebars = {
       className: 'red',
       label: 'Index',
     },
+    'doc-without-sidebar',
+    'doc-with-another-sidebar',
     {
       type: 'category',
       label: 'Tests',
@@ -70,6 +72,7 @@ const sidebars = {
       ],
     },
   ],
+  anotherSidebar: ['dummy'],
 };
 module.exports = sidebars;
 

website/docs/guides/docs/sidebar.md

@@ -241,7 +241,7 @@ We have introduced three types of item types in the above example: `doc`, `categ
 - **[Link](#sidebar-item-link)**: link to any internal or external page
 - **[Category](#sidebar-item-category)**: creates a dropdown of sidebar items
 - **[Autogenerated](#sidebar-item-autogenerated)**: generate a sidebar slice automatically
-- **[\*Ref](#sidebar-association)**: link to a doc page, without associating it with the sidebar
+- **[\*Ref](#sidebar-item-ref)**: link to a doc page, without making the item take part in navigation generation
 
 ### Doc: link to a doc {#sidebar-item-doc}
 
@@ -966,31 +966,49 @@ module.exports = {
 };
 ```
 
-How does Docusaurus know which sidebar to display when browsing `commonDoc`? Answer: it doesn't, and we don't guarantee which sidebar it will pick. In this case, in order to remove the ambiguity, you can use the special `ref` sidebar item type.
+How does Docusaurus know which sidebar to display when browsing `commonDoc`? Answer: it doesn't, and we don't guarantee which sidebar it will pick.
 
-The `ref` type is identical to the [`doc` type](#sidebar-item-doc) in every way, except that it doesn't set the association. It only registers itself as a link but doesn't take part in generating navigation metadata. When [generating pagination](#generating-pagination) and displaying sidebar, `ref` items are completely ignored.
+When you add doc Y to sidebar X, it creates a two-way binding: sidebar X contains a link to doc Y, and when browsing doc Y, sidebar X will be displayed. But sometimes, we want to break either implicit binding:
 
-So you can turn the sidebars above into:
+1. _How do I generate a link to doc Y in sidebar X without making sidebar X displayed on Y?_ For example, when I include doc Y in multiple sidebars as in the example above, and I want to explicitly tell Docusaurus to display one sidebar?
+2. _How do I make sidebar X displayed when browsing doc Y, but sidebar X shouldn't contain the link to Y?_ For example, when Y is a "doc home page" and the sidebar is purely used for navigation?
+
+Front matter option `displayed_sidebar` will forcibly set the sidebar association. For the same example, you can still use doc shorthands without any special configuration:
 
 ```js title="sidebars.js"
 module.exports = {
   tutorialSidebar: {
-    'Category A': [
-      'doc1',
-      'doc2',
-      // highlight-next-line
-      {type: 'ref', id: 'commonDoc'},
-    ],
+    'Category A': ['doc1', 'doc2'],
   },
-  apiSidebar: ['doc3', 'doc4', 'commonDoc'],
+  apiSidebar: ['doc3', 'doc4'],
 };
 ```
 
-Now, although the link to `commonDoc` is still included in the `tutorialSidebar` sidebar, when browsing `commonDoc`, only `apiSidebar` can be possibly displayed.
+And then add a front matter:
+
+```md title="commonDoc.md"
+---
+displayed_sidebar: apiSidebar
+---
+```
+
+Which explicitly tells Docusaurus to display `apiSidebar` when browsing `commonDoc`. Using the same method, you can make sidebar X which doesn't contain doc Y appear on doc Y:
+
+```md title="home.md"
+---
+displayed_sidebar: tutorialSidebar
+---
+```
+
+Even when `tutorialSidebar` doesn't contain a link to `home`, it will still be displayed when viewing `home`.
+
+If you set `displayed_sidebar: null`, no sidebar will be displayed whatsoever on this page, and subsequently, no pagination either.
 
 ### Generating pagination {#generating-pagination}
 
-Docusaurus uses the sidebar to generate the "next" and "previous" pagination links at the bottom of each doc page. It strictly uses the sidebar that is displayed: if no sidebar is associated, no pagination is generated either.
+Docusaurus uses the sidebar to generate the "next" and "previous" pagination links at the bottom of each doc page. It strictly uses the sidebar that is displayed: if no sidebar is associated, it doesn't generate pagination either. However, the docs linked as "next" and "previous" are not guaranteed to display the same sidebar: they are included in this sidebar, but in their front matter, they may have a different `displayed_sidebar`.
+
+If a sidebar is displayed by setting `displayed_sidebar` front matter, and this sidebar doesn't contain the doc itself, no pagination is displayed.
 
 You can customize pagination with front matter `pagination_next` and `pagination_prev`. Consider this sidebar:
 
@@ -1021,6 +1039,33 @@ You can also disable displaying a pagination link with `pagination_next: null` o
 
 The pagination label by default is the sidebar label. You can use the front matter `pagination_label` to customize how this doc appears in the pagination.
 
+### The `ref` item {sidebar-item-ref}
+
+The `ref` type is identical to the [`doc` type](#sidebar-item-doc) in every way, except that it doesn't participate in generating navigation metadata. It only registers itself as a link. When [generating pagination](#generating-pagination) and [displaying sidebar](#sidebar-association), `ref` items are completely ignored.
+
+Consider this example:
+
+```js title="sidebars.js"
+module.exports = {
+  tutorialSidebar: {
+    'Category A': [
+      'doc1',
+      'doc2',
+      // highlight-next-line
+      {type: 'ref', id: 'commonDoc'},
+      'doc5',
+    ],
+  },
+  apiSidebar: ['doc3', 'doc4', 'commonDoc'],
+};
+}
+```
+
+You can think of the `ref` type as the equivalent to doing the following:
+
+- Setting `displayed_sidebar: tutorialSidebar` for `commonDoc` (`ref` is ignored in sidebar association)
+- Setting `pagination_next: doc5` for `doc2` and setting `pagination_prev: doc2` for `doc5` (`ref` is ignored in pagination generation)
+
 ## Passing custom props {#passing-custom-props}
 
 To pass in custom props to a swizzled sidebar item, add the optional `customProps` object to any of the items: