Fix hydration behavior of patchRoutesOnMiss when v7_partialHydration is enabled

.changeset/sour-dryers-walk.md

@@ -0,0 +1,9 @@
+---
+"react-router-dom": patch
+"react-router": patch
+"@remix-run/router": patch
+---
+
+Fix initial hydration behavior when using `future.v7_partialHydration` along with `unstable_patchRoutesOnMiss`
+
+- During initial hydration, `router.state.matches` will now include any partial matches so that we can render ancestor `HydrateFallback` components

package.json

@@ -105,13 +105,13 @@
   },
   "filesize": {
     "packages/router/dist/router.umd.min.js": {
-      "none": "57.1 kB"
+      "none": "57.2 kB"
     },
     "packages/react-router/dist/react-router.production.min.js": {
-      "none": "14.9 kB"
+      "none": "15.0 kB"
     },
     "packages/react-router/dist/umd/react-router.production.min.js": {
-      "none": "17.4 kB"
+      "none": "17.5 kB"
     },
     "packages/react-router-dom/dist/react-router-dom.production.min.js": {
       "none": "17.3 kB"

packages/react-router-dom/__tests__/partial-hydration-test.tsx

@@ -2,7 +2,7 @@ import "@testing-library/jest-dom";
 import { act, render, screen, waitFor } from "@testing-library/react";
 import * as React from "react";
 import type { LoaderFunction } from "react-router";
-import { RouterProvider as ReactRouter_RouterPRovider } from "react-router";
+import { RouterProvider as ReactRouter_RouterProvider } from "react-router";
 import {
   Outlet,
   RouterProvider as ReactRouterDom_RouterProvider,
@@ -28,7 +28,181 @@ describe("v7_partialHydration", () => {
   });
 
   describe("createMemoryRouter", () => {
-    testPartialHydration(createMemoryRouter, ReactRouter_RouterPRovider);
+    testPartialHydration(createMemoryRouter, ReactRouter_RouterProvider);
+
+    // these tests only run for memory since we just need to set initialEntries
+    it("supports partial hydration w/patchRoutesOnMiss (leaf fallback)", async () => {
+      let parentDfd = createDeferred();
+      let childDfd = createDeferred();
+      let router = createMemoryRouter(
+        [
+          {
+            path: "/",
+            Component() {
+              return (
+                <>
+                  <h1>Root</h1>
+                  <Outlet />
+                </>
+              );
+            },
+            children: [
+              {
+                id: "parent",
+                path: "parent",
+                HydrateFallback: () => <p>Parent Loading...</p>,
+                loader: () => parentDfd.promise,
+                Component() {
+                  let data = useLoaderData() as string;
+                  return (
+                    <>
+                      <h2>{`Parent - ${data}`}</h2>
+                      <Outlet />
+                    </>
+                  );
+                },
+              },
+            ],
+          },
+        ],
+        {
+          future: {
+            v7_partialHydration: true,
+          },
+          unstable_patchRoutesOnMiss({ path, patch }) {
+            if (path === "/parent/child") {
+              patch("parent", [
+                {
+                  path: "child",
+                  loader: () => childDfd.promise,
+                  Component() {
+                    let data = useLoaderData() as string;
+                    return <h3>{`Child - ${data}`}</h3>;
+                  },
+                },
+              ]);
+            }
+          },
+          initialEntries: ["/parent/child"],
+        }
+      );
+      let { container } = render(
+        <ReactRouter_RouterProvider router={router} />
+      );
+
+      parentDfd.resolve("PARENT DATA");
+      expect(getHtml(container)).toMatchInlineSnapshot(`
+        "<div>
+          <h1>
+            Root
+          </h1>
+          <p>
+            Parent Loading...
+          </p>
+        </div>"
+      `);
+
+      childDfd.resolve("CHILD DATA");
+      await waitFor(() => screen.getByText(/CHILD DATA/));
+      expect(getHtml(container)).toMatchInlineSnapshot(`
+        "<div>
+          <h1>
+            Root
+          </h1>
+          <h2>
+            Parent - PARENT DATA
+          </h2>
+          <h3>
+            Child - CHILD DATA
+          </h3>
+        </div>"
+      `);
+    });
+
+    it("supports partial hydration w/patchRoutesOnMiss (root fallback)", async () => {
+      let parentDfd = createDeferred();
+      let childDfd = createDeferred();
+      let router = createMemoryRouter(
+        [
+          {
+            path: "/",
+            HydrateFallback: () => <p>Root Loading...</p>,
+            Component() {
+              return (
+                <>
+                  <h1>Root</h1>
+                  <Outlet />
+                </>
+              );
+            },
+            children: [
+              {
+                id: "parent",
+                path: "parent",
+                loader: () => parentDfd.promise,
+                Component() {
+                  let data = useLoaderData() as string;
+                  return (
+                    <>
+                      <h2>{`Parent - ${data}`}</h2>
+                      <Outlet />
+                    </>
+                  );
+                },
+              },
+            ],
+          },
+        ],
+        {
+          future: {
+            v7_partialHydration: true,
+          },
+          unstable_patchRoutesOnMiss({ path, patch }) {
+            if (path === "/parent/child") {
+              patch("parent", [
+                {
+                  path: "child",
+                  loader: () => childDfd.promise,
+                  Component() {
+                    let data = useLoaderData() as string;
+                    return <h3>{`Child - ${data}`}</h3>;
+                  },
+                },
+              ]);
+            }
+          },
+          initialEntries: ["/parent/child"],
+        }
+      );
+      let { container } = render(
+        <ReactRouter_RouterProvider router={router} />
+      );
+
+      parentDfd.resolve("PARENT DATA");
+      expect(getHtml(container)).toMatchInlineSnapshot(`
+        "<div>
+          <p>
+            Root Loading...
+          </p>
+        </div>"
+      `);
+
+      childDfd.resolve("CHILD DATA");
+      await waitFor(() => screen.getByText(/CHILD DATA/));
+      expect(getHtml(container)).toMatchInlineSnapshot(`
+        "<div>
+          <h1>
+            Root
+          </h1>
+          <h2>
+            Parent - PARENT DATA
+          </h2>
+          <h3>
+            Child - CHILD DATA
+          </h3>
+        </div>"
+      `);
+    });
   });
 });
 
@@ -39,7 +213,7 @@ function testPartialHydration(
     | typeof createMemoryRouter,
   RouterProvider:
     | typeof ReactRouterDom_RouterProvider
-    | typeof ReactRouter_RouterPRovider
+    | typeof ReactRouter_RouterProvider
 ) {
   let consoleWarn: jest.SpyInstance;
 

packages/react-router/lib/hooks.tsx

@@ -683,10 +683,27 @@ export function _renderMatches(
   future: RemixRouter["future"] | null = null
 ): React.ReactElement | null {
   if (matches == null) {
-    if (dataRouterState?.errors) {
+    if (!dataRouterState) {
+      return null;
+    }
+
+    if (dataRouterState.errors) {
       // Don't bail if we have data router errors so we can render them in the
       // boundary.  Use the pre-matched (or shimmed) matches
       matches = dataRouterState.matches as DataRouteMatch[];
+    } else if (
+      future?.v7_partialHydration &&
+      parentMatches.length === 0 &&
+      !dataRouterState.initialized &&
+      dataRouterState.matches.length > 0
+    ) {
+      // Don't bail if we're initializing with partial hydration and we have
+      // router matches.  That means we're actively running `patchRoutesOnMiss`
+      // so we should render down the partial matches to the appropriate
+      // `HydrateFallback`.  We only do this if `parentMatches` is empty so it
+      // only impacts the root matches for `RouterProvider` and no descendant
+      // `<Routes>`
+      matches = dataRouterState.matches as DataRouteMatch[];
     } else {
       return null;
     }