London| 26 March SDC | Jamal Laqdiem| Sprint 3 | Middleware exercises

custome-middlewares/.gitignore

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+node_modules/

custome-middlewares/dist/custom-middleware/array-validator.js

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+const arrayValidator = (req, res, next) => {
+    const body = req.body;
+    // 1. Is it a valid array?
+    if (!Array.isArray(body)) {
+        return res.status(400).send("Bad Request: Body must be a JSON array.");
+    }
+    // 2. Are all items inside the array strings?
+    const allStrings = body.every((item) => typeof item === "string");
+    if (!allStrings) {
+        return res
+            .status(400)
+            .send("Bad Request: All array elements must be strings.");
+    }
+    next();
+};
+export default arrayValidator;

custome-middlewares/dist/custom-middleware/username-validator.js

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+const usernameLoader = (req, res, next) => {
+    const usernameHeader = req.headers["x-username"];
+    if (typeof usernameHeader === "string") {
+        req.username = usernameHeader;
+    }
+    if (!req.username) {
+        return res
+            .status(401)
+            .send("Unauthorized: You must provide a valid x-username header.");
+    }
+    next();
+};
+export default usernameLoader;

custome-middlewares/dist/main.js

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+import express from "express";
+import arrayValidator from "./custom-middleware/array-validator.js";
+import usernameLoader from "./custom-middleware/username-validator.js";
+const app = express();
+const port = 3000;
+app.use(express.json());
+app.post("/", usernameLoader, arrayValidator, (req, res) => {
+    const subjects = req.body;
+    const count = subjects.length;
+    const subjectList = subjects.join(", ");
+    // 1. Format the authentication message using the custom header middleware
+    let authMessage = req.username
+        ? `You are authenticated as ${req.username}.`
+        : "You are not authenticated.";
+    // 2. Format the subject list counts from the array validator middleware
+    let subjectMessage = count === 1
+        ? `You have requested information about 1 subject: ${subjectList}.`
+        : `You have requested information about ${count} subjects${count > 0 ? ": " + subjectList : "."}`;
+    res.send(`${authMessage}\n\n${subjectMessage}`);
+});
+app.listen(port, () => {
+    console.log(`Middleware exercises server running on port ${port}`);
+});