London | 26-SDC-March | Zobeir Rigi | Sprint 3 | Middleware exercises

middleware-exercises/.gitignore

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+node_modules/

middleware-exercises/app.js

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+import express from "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 parseBodyMiddleware = (req, res, next) => {
+    let requestBody = "";
+
+    req.on("data", (chunk) => {
+        requestBody += chunk;
+    });
+
+    req.on("end", () => {
+        try {
+            const parsedBody = JSON.parse(requestBody);
+
+            if (!Array.isArray(parsedBody)) {
+                return res.status(400).send("Body must be a JSON array");
+            }
+
+            for (const item of parsedBody) {
+                if (typeof item !== "string") {
+                    return res
+                        .status(400)
+                        .send("All array items must be strings");
+                }
+            }
+
+            req.body = parsedBody;
+
+            next();
+        } catch {
+            return res.status(400).send("Invalid JSON");
+        }
+    });
+};
+
+app.use(usernameMiddleware);
+app.use(parseBodyMiddleware);
+
+app.post("/", (req, res) => {
+    let authenticationMessage;
+
+    if (req.username) {
+        authenticationMessage =
+            `You are authenticated as ${req.username}.`;
+    } else {
+        authenticationMessage =
+            "You are not authenticated.";
+    }
+
+    const subjects = req.body;
+    const numberOfSubjects = subjects.length;
+
+    let subjectsMessage = `You have requested information about ${numberOfSubjects} subject`;
+
+    if (numberOfSubjects !== 1) {
+        subjectsMessage += "s";
+    }
+
+    if (numberOfSubjects > 0) {
+        subjectsMessage += `: ${subjects.join(", ")}`;
+    }
+
+    subjectsMessage += ".";
+
+ res.send(
+    `${authenticationMessage}\n\n${subjectsMessage}\n`
+);
+});
+
+app.listen(3000, () => {
+    console.log("Server running on port 3000");
+});

middleware-exercises/existingMiddleware.js

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+import express from "express";
+const app = express();
+
+const usernameMiddleware = (req, res, next) => {
+    req.username = req.get("X-Username") || null;
+    next();
+};
+
+const validateBodyMiddleware = (req, res, next) => {
+    if (!Array.isArray(req.body)) {
+        return res.status(400).send("Body must be a JSON array");
+    }
+
+    for (const item of req.body) {
+        if (typeof item !== "string") {
+            return res
+                .status(400)
+                .send("All array items must be strings");
+        }
+    }
+
+    next();
+};
+
+app.use(express.json());
+app.use(usernameMiddleware);
+app.use(validateBodyMiddleware)
+
+app.post("/", (req, res) => {
+    let authenticationMessage;
+
+    if (req.username) {
+        authenticationMessage =
+            `You are authenticated as ${req.username}.`;
+    } else {
+        authenticationMessage =
+            "You are not authenticated.";
+    }
+
+    const subjects = req.body;
+    const numberOfSubjects = subjects.length;
+
+    let subjectsMessage = `You have requested information about ${numberOfSubjects} subject`;
+
+    if (numberOfSubjects !== 1) {
+        subjectsMessage += "s";
+    }
+
+    if (numberOfSubjects > 0) {
+        subjectsMessage += `: ${subjects.join(", ")}`;
+    }
+
+    subjectsMessage += ".";
+
+    res.send(
+        `${authenticationMessage}\n\n${subjectsMessage}\n`
+    );
+});
+
+app.listen(3000, () => {
+    console.log("Server running on port 3000");
+});
+
+
+// curl -X POST --data '["Bees"]' -H "Content-Type: application/json" -H "X-Username: Ahmed" http://localhost:3000