feat(prod-server): add handleSSRFallback hook

.changeset/kind-apples-joke.md

@@ -0,0 +1,7 @@
+---
+'@modern-js/prod-server': minor
+'@modern-js/server-core': minor
+---
+
+feat: add server SSR fallback hook
+feat: 新增 server SSR 降级 hook 实现

packages/server/core/src/plugin.ts

@@ -125,6 +125,11 @@ const extendContext = createAsyncPipeline<
 
 const handleError = createParallelWorkflow<{ error: Error }>();
 
+const handleSSRFallback = createParallelWorkflow<{
+  ctx: ModernServerContext;
+  type: 'query' | 'error' | 'header';
+}>();
+
 export type RequestResult = { isfinish: boolean };
 const beforeMatch = createAsyncPipeline<
   { context: ModernServerContext },
@@ -212,6 +217,7 @@ const serverHooks = {
   extendSSRContext,
   extendContext,
   handleError,
+  handleSSRFallback,
   beforeMatch,
   afterMatch,
   prefetch,

packages/server/prod-server/src/libs/render/index.ts

@@ -76,8 +76,9 @@ export const createRenderHandler: CreateRenderHandler = ({
     }
 
     // handles ssr first
-    const useCSR =
-      forceCSR && (ctx.query.csr || ctx.headers[calcFallback(metaName)]);
+    const queryCSR = ctx.query.csr;
+    const headerFallback = ctx.headers[calcFallback(metaName)];
+    const useCSR = forceCSR && (queryCSR || headerFallback);
     if (route.isSSR && !useCSR) {
       try {
         const userAgent = ctx.getReqHeader('User-Agent') as string | undefined;
@@ -118,7 +119,11 @@ export const createRenderHandler: CreateRenderHandler = ({
           (err as Error).stack || (err as Error).message,
         );
         ctx.res.set(calcFallback(metaName), '1');
+        await runner.handleSSRFallback({ ctx, type: 'error' });
       }
+    } else if (route.isSSR && useCSR) {
+      const fallbackType: 'query' | 'header' = queryCSR ? 'query' : 'header';
+      await runner.handleSSRFallback({ ctx, type: fallbackType });
     }
 
     return {

packages/server/prod-server/tests/render.test.ts

@@ -31,6 +31,9 @@ describe('test render function', () => {
         extendSSRContext: () => {
           // empty
         },
+        handleSSRFallback: () => {
+          // empty
+        },
       } as any,
     );
 
@@ -121,6 +124,9 @@ describe('test render function', () => {
         extendSSRContext: () => {
           // empty
         },
+        handleSSRFallback: () => {
+          // empty
+        },
       } as any,
     });
     expect(renderResult!.content).toMatch('Modern.js');
@@ -166,6 +172,9 @@ describe('test render function', () => {
         extendSSRContext: () => {
           // empty
         },
+        handleSSRFallback: () => {
+          // empty
+        },
       } as any,
     });
     expect(renderResult!.content.toString()).toMatch('csr');
@@ -209,6 +218,9 @@ describe('test render function', () => {
         extendSSRContext: () => {
           // empty
         },
+        handleSSRFallback: () => {
+          // empty
+        },
       } as any,
     });
     expect(renderResult!.content.toString()).toMatch('csr');