London | 25-SDC-July | Mikiyas Gebremichal | Sprint 3 | Middleware exercises

.gitignore

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+node_modules

middleware_exercise/builtin_middlewares/biltinmw.js

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+const express = require("express");
+const app = express();
+
+// 🧱 Middleware 1: Check for X-Username header (same as before)
+function usernameMiddleware(req, res, next) {
+  const username = req.header("X-Username");
+  req.username = username ? username : null;
+  next();
+}
+
+// ✅ Use built-in Express middleware to parse JSON
+// This automatically parses JSON bodies if Content-Type is application/json
+// You don’t need to collect chunks manually anymore!
+
+app.post("/", usernameMiddleware, express.json(), (req, res) => {
+  const username = req.username;
+  const subjects = req.body;
+
+  // Validate that body is an array of strings
+  if (!Array.isArray(subjects)) {
+    return res.status(400).send("Request body must be a JSON array.");
+  }
+
+  const allStrings = subjects.every((item) => typeof item === "string");
+  if (!allStrings) {
+    return res.status(400).send("All array elements must be strings.");
+  }
+
+  const count = subjects.length;
+  let response = "";
+
+  if (username) {
+    response += `You are authenticated as ${username}.\n\n`;
+  } else {
+    response += "You are not authenticated.\n\n";
+  }
+
+  if (count === 1) {
+    response += `You have requested information about 1 subject: ${subjects[0]}.`;
+  } else if (count > 1) {
+    response += `You have requested information about ${count} subjects: ${subjects.join(
+      ", "
+    )}.`;
+  } else {
+    response += "You have requested information about 0 subjects.";
+  }
+
+  res.send(response);
+});
+
+app.listen(3000, () => {
+  console.log("✅ Server running on http://localhost:3000");
+});
+//   curl -X POST \
+//   --data '["Bees"]' \
+//   -H "Content-Type: application/json" \
+//   -H "X-Username: Ahmed" \
+//   http://localhost:3000