fix(ssr): fix on-component directives rendering (#12661)

fix #10733

Author: TheAlexLichter

Diff for: packages/server-renderer/src/render.ts

@@ -206,6 +206,11 @@ function renderComponentInner(node, isRoot, context) {
       type: 'Component',
       prevActive
     })
+    if (isDef(node.data) && isDef(node.data.directives)) {
+      childNode.data = childNode.data || {}
+      childNode.data.directives = node.data.directives
+      childNode.isComponentRootElement = true
+    }
     renderNode(childNode, isRoot, context)
   }
 
@@ -372,7 +377,10 @@ function renderStartingTag(node: VNode, context) {
           if (dirRenderer) {
             // directives mutate the node's data
             // which then gets rendered by modules
-            dirRenderer(node, dirs[i])
+            dirRenderer(
+              node.isComponentRootElement ? node.parent : node,
+              dirs[i]
+            )
           }
         }
       }

Diff for: packages/server-renderer/test/ssr-string.spec.ts

@@ -1086,7 +1086,7 @@ describe('SSR: renderToString', () => {
     )
   })
 
-  it('custom directives', done => {
+  it('custom directives on raw element', done => {
     const renderer = createRenderer({
       directives: {
         'class-prefixer': (node, dir) => {
@@ -1129,6 +1129,98 @@ describe('SSR: renderToString', () => {
     )
   })
 
+  it('custom directives on component', done => {
+    const Test = {
+      template: '<span>hello world</span>'
+    }
+    const renderer = createRenderer({
+      directives: {
+        'class-prefixer': (node, dir) => {
+          if (node.data.class) {
+            node.data.class = `${dir.value}-${node.data.class}`
+          }
+          if (node.data.staticClass) {
+            node.data.staticClass = `${dir.value}-${node.data.staticClass}`
+          }
+        }
+      }
+    })
+    renderer.renderToString(
+      new Vue({
+        template:
+          '<p><Test v-class-prefixer="\'my\'" class="class1" :class="\'class2\'" /></p>',
+        components: { Test }
+      }),
+      (err, result) => {
+        expect(err).toBeNull()
+        expect(result).toContain(
+          '<p data-server-rendered="true"><span class="my-class1 my-class2">hello world</span></p>'
+        )
+        done()
+      }
+    )
+  })
+
+  it('custom directives on element root of a component', done => {
+    const Test = {
+      template:
+        '<span v-class-prefixer="\'my\'" class="class1" :class="\'class2\'">hello world</span>'
+    }
+    const renderer = createRenderer({
+      directives: {
+        'class-prefixer': (node, dir) => {
+          if (node.data.class) {
+            node.data.class = `${dir.value}-${node.data.class}`
+          }
+          if (node.data.staticClass) {
+            node.data.staticClass = `${dir.value}-${node.data.staticClass}`
+          }
+        }
+      }
+    })
+    renderer.renderToString(
+      new Vue({
+        template: '<p><Test /></p>',
+        components: { Test }
+      }),
+      (err, result) => {
+        expect(err).toBeNull()
+        expect(result).toContain(
+          '<p data-server-rendered="true"><span class="my-class1 my-class2">hello world</span></p>'
+        )
+        done()
+      }
+    )
+  })
+
+  it('custom directives on element with parent element', done => {
+    const renderer = createRenderer({
+      directives: {
+        'class-prefixer': (node, dir) => {
+          if (node.data.class) {
+            node.data.class = `${dir.value}-${node.data.class}`
+          }
+          if (node.data.staticClass) {
+            node.data.staticClass = `${dir.value}-${node.data.staticClass}`
+          }
+        }
+      }
+    })
+    renderer.renderToString(
+      new Vue({
+        template:
+          '<p><span v-class-prefixer="\'my\'" class="class1" :class="\'class2\'">hello world</span></p>'
+      }),
+      (err, result) => {
+        expect(err).toBeNull()
+        expect(result).toContain(
+          '<p data-server-rendered="true"><span class="my-class1 my-class2">hello world</span></p>'
+        )
+        done()
+      }
+    )
+  })
+
   it('should not warn for custom directives that do not have server-side implementation', done => {
     renderToString(
       new Vue({

Diff for: src/core/vdom/vnode.ts

@@ -33,6 +33,7 @@ export default class VNode {
   fnOptions?: ComponentOptions | null // for SSR caching
   devtoolsMeta?: Object | null // used to store functional render context for devtools
   fnScopeId?: string | null // functional scope id support
+  isComponentRootElement?: boolean | null // for SSR directives
 
   constructor(
     tag?: string,