Introduction to md5-json

The `md5-json` is a powerful and efficient library for generating MD5 hashes from JSON data structures. This guide will introduce you to the many useful APIs provided by `md5-json` and show you how to incorporate them into your application for enhanced data security and validation.

API Explanations and Code Snippets

1. Generating MD5 Hash from JSON

The most basic use of `md5-json` is to generate an MD5 hash from a given JSON object. This can be achieved using the `hash` function.

  const md5Json = require('md5-json');
  let jsonObject = { name: "John", age: 30, city: "New York" };
  let hash = md5Json.hash(jsonObject);
  console.log(hash); // Outputs the MD5 hash of the JSON object

2. Comparing JSON Objects

You can compare two JSON objects by their MD5 hashes to check if they are identical.

  let jsonObject1 = { name: "John", age: 30, city: "New York" };
  let jsonObject2 = { name: "John", age: 30, city: "New York" };
  
  let hash1 = md5Json.hash(jsonObject1);
  let hash2 = md5Json.hash(jsonObject2);
  
  if (hash1 === hash2) {
    console.log("The JSON objects are identical");
  } else {
    console.log("The JSON objects are different");
  }

3. Verifying Data Integrity

Use `md5-json` to verify the integrity of your data by matching the generated hash with a stored one.

  let storedHash = "d2d2d2d2d2d2d2d2d2d2d2d2d2d2d2d2";
  let currentHash = md5Json.hash(jsonObject);
  
  if (currentHash === storedHash) {
    console.log("Data integrity verified.");
  } else {
    console.log("Data has been altered.");
  }

App Example Using md5-json APIs

Let’s build a small Node.js application that uses `md5-json` APIs to validate user data.

  const express = require('express');
  const md5Json = require('md5-json');
  
  const app = express();
  app.use(express.json());
  
  // Endpoint to create user and store hash
  let userData = [];
  
  app.post('/create-user', (req, res) => {
    let user = req.body;
    let hash = md5Json.hash(user);
    userData.push({ user, hash });
    res.send('User created and hash stored.');
  });
  
  // Endpoint to validate user data
  app.post('/validate-user', (req, res) => {
    let user = req.body;
    let currentHash = md5Json.hash(user);
    
    let storedUser = userData.find(item => md5Json.hash(item.user) === currentHash);
    
    if (storedUser) {
      res.send('User data is valid.');
    } else {
      res.send('User data is invalid.');
    }
  });
  
  app.listen(3000, () => {
    console.log('Server is running on port 3000');
  });

With these APIs and app example, you can start using `md5-json` in your applications for secure and validated data handling.

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