1 files changed, 43 insertions, 0 deletions
diff --git a/packages/integrations/node/src/middleware.ts b/packages/integrations/node/src/middleware.ts
new file mode 100644
index 000000000..a936dc5bc
--- /dev/null
+++ b/packages/integrations/node/src/middleware.ts
@@ -0,0 +1,43 @@
+import { createAppHandler } from './serve-app.js';
+import type { RequestHandler } from "./types.js";
+import type { NodeApp } from "astro/app/node";
+
+/**
+ * Creates a middleware that can be used with Express, Connect, etc.
+ * 
+ * Similar to `createAppHandler` but can additionally be placed in the express
+ * chain as an error middleware.
+ * 
+ * https://expressjs.com/en/guide/using-middleware.html#middleware.error-handling
+ */
+export default function createMiddleware(
+    app: NodeApp,
+): RequestHandler {
+    const handler = createAppHandler(app)
+    const logger = app.getAdapterLogger()
+    // using spread args because express trips up if the function's
+    // stringified body includes req, res, next, locals directly
+    return async function (...args) {
+        // assume normal invocation at first
+        const [req, res, next, locals] = args;
+        // short circuit if it is an error invocation
+        if (req instanceof Error) {
+            const error = req;
+            if (next) {
+                return next(error);
+            } else {
+                throw error;
+            }
+        }
+		try {
+			await handler(req, res, next, locals);
+		} catch (err) {
+			logger.error(`Could not render ${req.url}`);
+			console.error(err);
+			if (!res.headersSent) {
+				res.writeHead(500, `Server error`);
+				res.end();
+			}
+		}
+    }
+}