We'll explore how to implement the "GET ALL POSTS" route in the postsRoutes.js file. This route retrieves a list of all posts from the data source (database/posts.json) and sends them as a response to the client.

Importing Required Modules and Dependencies

At the beginning of the file, we import the necessary modules and dependencies:

const express = require("express");
const fs = require("fs/promises");
const validatePostData = require("../middlewares/validateData");

• express: We import the Express framework for building our routes;
• fs/promises: This module provides asynchronous file operations, which we'll use to read data from a JSON file;
• validatePostData: Although not used in this route, we import the validatePostData middleware, which will be helpful for data validation in later chapters.

Initializing an Express Router

We initialize an instance of an Express router, which will handle all routes defined within this file:

const router = express.Router();

Creating a Function to Read Data

We define an asynchronous function named readData to read data from a JSON file. This function ensures that data is retrieved properly and handles errors:

// Function to read data from the JSON file
async function readData() {
  try {
    // Read the contents of the `posts.json` file
    const data = await fs.readFile("./database/posts.json");
    // Parse the JSON data into a JavaScript object
    return JSON.parse(data);
  } catch (error) {
    // If an error occurs during reading or parsing, throw the error
    throw error;
  }
}

• fs.readFile: We use fs.readFile to read the contents of the ./database/posts.json file;
• JSON.parse: The data retrieved from the file is parsed into a JavaScript object;
• Error Handling: If any errors occur during the reading or parsing process, they are caught, and the error is thrown.

Defining the "GET ALL POSTS" Route

Here's how we define the "GET ALL POSTS" route within the router:

// GET ALL POSTS
router.get("/", async (req, res, next) => {
  try {
    // Call the `readData` function to retrieve the list of posts
    const data = await readData();
    // Send the retrieved data as the response
    res.status(200).send(data);
  } catch (error) {
    // If an error occurs during data retrieval or sending the response
    console.error(error.message); // Log the error to the console for debugging
  }
});

Route Definition: We specify that this route handles HTTP GET requests to the root path (/).

Route Handler: Inside the route handler function:

• We call the readData function to retrieve the list of posts from the JSON file;
• If the data retrieval is successful, we send the retrieved data as the response using res.send(data);
• If any errors occur during this process, we catch the error, log it to the console for debugging (console.error(error.message)), and continue.

Complete code of the postsRoutes.js file at this step

const express = require("express");
const fs = require("fs/promises");
const validatePostData = require("../middlewares/validateData");

const router = express.Router();

// Function to read data from the JSON file
async function readData() {
  try {
    // Read the contents of the `posts.json` file
    const data = await fs.readFile("./database/posts.json");
    // Parse the JSON data into a JavaScript object
    return JSON.parse(data);
  } catch (error) {
    // If an error occurs during reading or parsing, throw the error
    throw error;
  }
}

// GET ALL POSTS
router.get("/", async (req, res, next) => {
  try {
    // Call the `readData` function to retrieve the list of posts
    const data = await readData();
    // Send the retrieved data as the response
    res.status(200).send(data);
  } catch (error) {
    // If an error occurs during data retrieval or sending the response
    console.error(error.message); // Log the error to the console for debugging
  }
});