Manchester | 26-Jun-SDC | Fithi Teklom | Sprint 3 | Middleware exercise

.gitignore

@@ -0,0 +1 @@
+node_modules/

middleware-built-in/server.js

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+const express = require("express");
+
+const app = express();
+
+const usernameMiddleware = (req, res, next) => {
+  const username = req.get("X-Username");
+
+  if (username) {
+    req.username = username;
+  } else {
+    req.username = null;
+  }
+
+  next();
+};
+
+app.use(express.json());
+
+const validateSubjects = (req, res, next) => {
+  if (!Array.isArray(req.body) || !req.body.every(item => typeof item === "string")) {
+    return res
+      .status(400)
+      .send("Request body must be a JSON array of strings.");
+  }
+
+  next();
+};
+
+
+app.post("/", usernameMiddleware, validateSubjects, (req, res) => {
+  const username = req.username;
+  const subjects = req.body;
+  const subjectCount = subjects.length;
+
+  const authenticationMessage = username
+    ? `You are authenticated as ${username}.`
+    : "You are not authenticated.";
+
+  let subjectsMessage;
+
+  if (subjectCount === 0) {
+    subjectsMessage = "You have requested information about 0 subjects.";
+  } else {
+    const subjectWord = subjectCount === 1 ? "subject" : "subjects";
+
+    subjectsMessage = `You have requested information about ${subjectCount} ${subjectWord}: ${subjects.join(", ")}.`;
+  }
+
+  res.send(`${authenticationMessage}\n\n${subjectsMessage}\n`);
+});
+
+
+app.listen(3001, () => {
+  console.log("Server listening on port 3001");
+});

middleware-custom/server.js

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+const express = require("express");
+
+const app = express();
+
+const usernameMiddleware = (req, res, next) => {
+  const username = req.get("X-Username");
+
+  if (username) {
+    req.username = username;
+  } else {
+    req.username = null;
+  }
+
+  next();
+};
+
+const bodyMiddleware = (req, res, next) => {
+  const chunks = [];
+
+  req.on("data", (chunk) => {
+    chunks.push(chunk);
+  });
+
+  req.on("end", () => {
+    try {
+      const body = JSON.parse(Buffer.concat(chunks).toString("utf8"));
+
+      if (!Array.isArray(body) || !body.every(item => typeof item === "string")) {
+        return res
+          .status(400)
+          .send("Request body must be a JSON array of strings.");
+      }
+
+      req.body = body;
+      next();
+    } catch {
+      res.status(400).send("Request body must be valid JSON.");
+    }
+  });
+};
+
+
+app.post("/", usernameMiddleware, bodyMiddleware, (req, res) => {
+  const username = req.username;
+  const subjects = req.body;
+  const subjectCount = subjects.length;
+
+  const authenticationMessage = username
+    ? `You are authenticated as ${username}.`
+    : "You are not authenticated.";
+
+  let subjectsMessage;
+
+  if (subjectCount === 0) {
+    subjectsMessage = "You have requested information about 0 subjects.";
+  } else {
+    const subjectWord = subjectCount === 1 ? "subject" : "subjects";
+
+    subjectsMessage = `You have requested information about ${subjectCount} ${subjectWord}: ${subjects.join(", ")}.`;
+  }
+
+  res.send(`${authenticationMessage}\n\n${subjectsMessage}\n`);
+});
+
+app.listen(3001, () => {
+  console.log("Server listening on port 3001");
+});