Understanding ORM and ODM: A Simple Guide for Backend Developers

Sure! Here's a simple blog post explaining ORM and ODM for backend developers.

If you’re working on the backend of a web application and using a database to store data, you’ve likely heard of ORM and ODM. These terms might sound complicated at first, but they’re actually quite simple once you break them down. Let’s take a closer look at what ORM and ODM are and why they matter for backend development.

What is ORM?

ORM (Object-Relational Mapping) is a way to interact with relational databases (like MySQL or PostgreSQL) using your programming language (like JavaScript, Python, etc.) instead of writing complex SQL queries.

In simple terms, ORM helps you work with objects in your code and automatically saves or fetches them from tables in a relational database.

For example, if you have a User object in your code, ORM will help you save it as a row in a users table in the database. You don’t need to manually write SQL queries to insert or retrieve data.

How Does ORM Work?

Instead of using SQL commands to insert or select data, you use your programming language's syntax. Let’s look at a quick example using Sequelize (a popular ORM for Node.js):

const { User } = require('./models');

// Creating a new user
User.create({
  name: 'John Doe',
  email: 'johndoe@example.com'
}).then(user => {
  console.log(user);
});

In the example above, we’re creating a new user in the users table without writing SQL commands. The ORM takes care of the database interactions for you!

What is ODM?

ODM (Object-Document Mapping) is similar to ORM, but it’s used for NoSQL databases like MongoDB. Instead of dealing with tables (like in SQL), ODM works with documents (like JSON objects).

So, instead of inserting data into rows, you insert data as documents in collections. The process of saving and fetching data is similar to ORM, but it’s adapted for document-based databases.

For example, if you have a Product object, ODM will help you save it as a document in a products collection in MongoDB.

How Does ODM Work?

Let’s take Mongoose (a popular ODM for MongoDB) as an example. Here’s how you’d create a product document:

const mongoose = require('mongoose');
const Product = mongoose.model('Product', {
  name: String,
  price: Number
});

// Creating a new product
const newProduct = new Product({
  name: 'Awesome Product',
  price: 99.99
});

newProduct.save().then(product => {
  console.log(product);
});

In this case, you’re saving a product as a document in the products collection, without worrying about the underlying database details.

ORM vs ODM: Key Differences

• ORM is for SQL databases (like MySQL, PostgreSQL).

  • You work with tables and rows.

  • Example: Sequelize, TypeORM.

• ODM is for NoSQL databases (like MongoDB).

  • You work with documents and collections.

  • Example: Mongoose.

Why Do ORM and ODM Matter?

Both ORM and ODM simplify how you interact with databases. Instead of dealing with raw SQL commands or worrying about document structure, they let you focus on your code, improving productivity and reducing errors.

With ORM and ODM, you can:

• Save time by using your programming language instead of SQL.

• Write cleaner code that’s easier to maintain.

• Focus on logic rather than database intricacies.

Whether you’re using a relational database (SQL) or a NoSQL database, ORM and ODM tools help you work with data more efficiently. ORM is the go-to for SQL databases, while ODM is tailored for NoSQL databases. Both are essential for simplifying database interactions and keeping your codebase clean and maintainable.