Birmingham | 26-Jul-SDC | Merve Reis | Sprint 3 | Middleware CYF-1165

.gitignore

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+node_modules

middleware-exercises/Custom-Middleware.js

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+const express = require("express");
+
+const app = express();
+const PORT = 3000;
+
+// Middleware 1:check X-Username header
+function usernameMiddleware(req, res, next) {
+  const username = req.get("X-Username");
+
+  if (username) {
+    req.username = username;
+  } else {
+    req.username = null;
+  }
+
+  next();
+}
+
+// Middleware 2: parse and validate JSON array
+function bodyMiddleware(req, res, next) {
+  let body = "";
+
+  req.on("data", (chunk) => {
+    body += chunk;
+  });
+
+  req.on("end", () => {
+    try {
+      const parsedBody = JSON.parse(body);
+
+      if (!Array.isArray(parsedBody)) {
+        return res.status(400).send("Request body must be a JSON array.");
+      }
+
+      if (!parsedBody.every((item) => typeof item === "string")) {
+        return res.status(400).send("Array must contain only strings.");
+      }
+
+      req.body = parsedBody;
+      next();
+    } catch (error) {
+      res.status(400).send("Request body must be valid JSON.");
+    }
+  });
+}
+
+app.use(usernameMiddleware);
+app.use(bodyMiddleware);
+
+app.post("/", (req, res) => {
+  const subjects = req.body;
+  const authenticationMessage = req.username
+    ? `You are authenticated as ${req.username}.`
+    : "You are not authenticated.";
+
+  res.send(
+    `${authenticationMessage}\n\n` +
+      `You have requested information about ${subjects.length} ` +
+      `${subjects.length === 1 ? "subject" : "subjects"}` +
+      `${subjects.length > 0 ? ": " + subjects.join(", ") : ""}.`,
+  );
+});
+
+app.listen(PORT, () => {
+  console.log(`Server running on http://localhost:${PORT}`);
+});

middleware-exercises/Off-shell-middlewares.js

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+import express from "express";
+
+const app = express();
+
+function usernameMiddleware(req, res, next) {
+  const username = req.get("X-Username");
+
+  if (username) {
+    req.username = username;
+  } else {
+    req.username = null;
+  }
+
+  next();
+}
+
+app.use(express.json());
+
+function bodyValidationMiddleware(req, res, next) {
+  if (!Array.isArray(req.body)) {
+    return res.status(400).send("Request body must be a JSON array.");
+  }
+
+  if (!req.body.every((item) => typeof item === "string")) {
+    return res.status(400).send("Array must contain only strings.");
+  }
+
+  next();
+}
+
+app.use(bodyValidationMiddleware);
+app.use(usernameMiddleware);
+
+app.post("/", (req, res) => {
+  const subjects = req.body;
+
+  if (req.username) {
+    res.send(
+      `You are authenticated as ${req.username}.\n\n` +
+        `You have requested information about ${subjects.length} ` +
+        `${subjects.length === 1 ? "subject" : "subjects"}` +
+        `${subjects.length > 0 ? `: ${subjects.join(", ")}` : ""}.`,
+    );
+  } else {
+    res.send(
+      `You are not authenticated.\n\n` +
+        `You have requested information about ${subjects.length} ` +
+        `${subjects.length === 1 ? "subject" : "subjects"}` +
+        `${subjects.length > 0 ? `: ${subjects.join(", ")}` : ""}.`,
+    );
+  }
+});
+
+app.listen(3000, () => {
+  console.log("Server running on http://localhost:3000");
+});