From 6b7d7db6cd9bf19751484de9cc37426e7e4ece58 Mon Sep 17 00:00:00 2001
From: HcySunYang <HcySunYang@outlook.com>
Date: Fri, 19 Feb 2021 11:27:45 +0800
Subject: [PATCH] fix(KeepAlive): adapt keepalive to ssr

---
 .../runtime-core/src/components/KeepAlive.ts  | 19 +++++++++++++------
 .../server-renderer/__tests__/render.spec.ts  | 14 +++++++++++++-
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/packages/runtime-core/src/components/KeepAlive.ts b/packages/runtime-core/src/components/KeepAlive.ts
index 6ad53fda72e..fabae785999 100644
--- a/packages/runtime-core/src/components/KeepAlive.ts
+++ b/packages/runtime-core/src/components/KeepAlive.ts
@@ -77,19 +77,26 @@ const KeepAliveImpl = {
   },
 
   setup(props: KeepAliveProps, { slots }: SetupContext) {
-    const cache: Cache = new Map()
-    const keys: Keys = new Set()
-    let current: VNode | null = null
-
     const instance = getCurrentInstance()!
-    const parentSuspense = instance.suspense
-
     // KeepAlive communicates with the instantiated renderer via the
     // ctx where the renderer passes in its internals,
     // and the KeepAlive instance exposes activate/deactivate implementations.
     // The whole point of this is to avoid importing KeepAlive directly in the
     // renderer to facilitate tree-shaking.
     const sharedContext = instance.ctx as KeepAliveContext
+
+    // if the internal renderer is not registered, it indicates that this is server-side rendering,
+    // for KeepAlive, we just need to render its children
+    if (!sharedContext.renderer) {
+      return slots.default
+    }
+
+    const cache: Cache = new Map()
+    const keys: Keys = new Set()
+    let current: VNode | null = null
+
+    const parentSuspense = instance.suspense
+
     const {
       renderer: {
         p: patch,
diff --git a/packages/server-renderer/__tests__/render.spec.ts b/packages/server-renderer/__tests__/render.spec.ts
index a02bf365cb7..46b12284b3d 100644
--- a/packages/server-renderer/__tests__/render.spec.ts
+++ b/packages/server-renderer/__tests__/render.spec.ts
@@ -8,7 +8,8 @@ import {
   ref,
   defineComponent,
   createTextVNode,
-  createStaticVNode
+  createStaticVNode,
+  KeepAlive
 } from 'vue'
 import { escapeHtml } from '@vue/shared'
 import { renderToString } from '../src/renderToString'
@@ -604,6 +605,17 @@ function testRender(type: string, render: typeof renderToString) {
       })
     })
 
+    describe('vnode component', () => {
+      test('KeepAlive', async () => {
+        const MyComp = {
+          render: () => h('p', 'hello')
+        }
+        expect(await render(h(KeepAlive, () => h(MyComp)))).toBe(
+          `<!--[--><p>hello</p><!--]-->`
+        )
+      })
+    })
+
     describe('raw vnode types', () => {
       test('Text', async () => {
         expect(await render(createTextVNode('hello <div>'))).toBe(