Stop Creating Prisma Clients Over and Over: Instantiating Prisma Just Once
Imagine you're building a complex application, and you need to interact with your database frequently. You might find yourself writing new PrismaClient() everywhere – in controllers, services, and even within loop iterations. This leads to excessive instantiation, potentially impacting performance and resource consumption.
But what if we could create a single Prisma client and reuse it across our entire application? This is where the concept of instantiating Prisma only once comes into play.
The Problem: Redundant Instantiation
Let's look at a typical scenario:
// Inside a controller
const prisma = new PrismaClient();
async function getUser(userId) {
const user = await prisma.user.findUnique({ where: { id: userId } });
return user;
}
// Inside a service
const prisma = new PrismaClient();
async function createOrder(userId, orderDetails) {
const order = await prisma.order.create({
data: {
...orderDetails,
userId,
},
});
return order;
}
In this example, we create a new Prisma client instance in both the controller and the service, potentially leading to performance bottlenecks as Prisma establishes multiple connections to your database.
The Solution: Singleton Pattern
The singleton pattern offers a clean and efficient way to ensure that Prisma is instantiated only once throughout your application.
How it works:
- Private Constructor: We make the constructor of our Prisma client class private, preventing direct instantiation from outside.
- Static Instance: We create a static instance of the Prisma client within the class itself.
- Lazy Initialization: We initialize the instance only when it's first requested.
Here's an implementation using a singleton pattern:
// prisma.ts
import { PrismaClient } from '@prisma/client';
class PrismaClientSingleton {
private static instance: PrismaClient;
private constructor() {
// Private constructor prevents direct instantiation.
}
static getInstance(): PrismaClient {
if (!PrismaClientSingleton.instance) {
PrismaClientSingleton.instance = new PrismaClient();
}
return PrismaClientSingleton.instance;
}
}
export default PrismaClientSingleton;
Usage:
// In your controller or service
import PrismaClientSingleton from './prisma';
const prisma = PrismaClientSingleton.getInstance();
async function getUser(userId) {
const user = await prisma.user.findUnique({ where: { id: userId } });
return user;
}
This way, regardless of where in your application you need to interact with the database, you always use the same instance of the Prisma client, ensuring optimal performance and resource utilization.
Beyond Singletons: Exploring Other Options
While the singleton pattern is a common approach, other options are available:
- Dependency Injection: You can use a dependency injection framework like InversifyJS or NestJS to manage the lifecycle of your Prisma client and ensure it's accessible across your application.
- Global Variable: In smaller applications, you can store the Prisma client in a global variable for easy access. However, this approach can be less maintainable and might lead to unintended side effects.
Choosing the Right Approach
The best way to instantiate Prisma depends on your specific project needs and coding style. Consider factors like project size, maintainability, and the level of complexity in your database interactions.
Remember, instantiating Prisma only once is a simple yet powerful technique that can significantly improve your application's performance and efficiency. By implementing this best practice, you can ensure your database interactions are optimized and your application runs smoothly.
