As a person coming from a Ruby on Rails background, I prefer ActiveRecord pattern to DataMapper. Obviously the choice will be based on the project and other criteria’s, but from my experience, most projects don’t require the complexity of Data Mapper.

When I started using Prisma, one of the confusions for me was how to add a custom method to a model.

Extending Prisma Client model object

Prisma documentation on custom models provides 3 ways to achieve it. From the 3 methods, I decided to go with Extending Prisma Client model object.

The major reason for going with this approach is its flexibility. By this method, we can define type-safe custom methods in models.

import { PrismaClient } from "@prisma/client";
import { prisma } from "@/../prisma";

function User(prismaUser: PrismaClient["user"]) {
  return Object.assign(prismaUser, {
    async signup(data) {
      // implement logic
    },

    async login(data) {
      // implement logic
    },
    
    async isUserFavorite(userId: string, entityId: number) {
      // implement logic
    },
  });
}

const user = User(prisma.user);

export default user;

and we can use both custom methods alongside inbuilt methods like findBy, count and upsert from the model object.

The major downside of Wrap model in a class is we won’t be able to use the inbuilt methods from the model instance.

Hope this is helpful.

Versions of Language/packages used in this post.