Approach for Factory Generation

[cball]

Throwing a few ideas out. The goal is a way to setup factories in a project that are automatically fully typed based on the Prisma types.

The createFactory definition

This is more manual, but it's also explicit and clear. prisma-factory would expose a createFactory function that returns an object with build and create functions.

We can also return hooks, like beforeCreate that allows us to do things like hash a password.

This is our easiest path, and one Echobind has already have implemented in projects with Prisma today.

---

Automatically Generate via a prisma generator

generator factories {
  provider = "prisma-factories"
}

This would require no user-defined factories unless they want to override the attribute generators. This could make for a nice default, but users might not be clear where things come from.

Prisma docs on generators: https://github.com/prisma/specs/tree/master/generators

---

Use Field annotation to map functions

model User {
  id        Int       @default(autoincrement()) @id
  createdAt DateTime  @default(now())
  email     String    @unique @factory(chance.email)
  name      String?   @factory(chance.company)
}

This would let the user override functions, but wouldn't handle some of the advanced cases we're considering (like beforeCreate hooks)

---

Give it a 🤔 and comment!

[cball]

Another thought from a recent Echobind team discussion:

Could we use the prisma generator approach to automatically generate typesafe functions? For example, given the schema above, we would use a prisma generator to build a createUserFactory function. The user could then use it as follows:

import { createUserFactory } from 'prisma-factories'

const chance = new Chance();

const DEFAULT_ATTRIBUTES = {
  id: chance.guid(),
  slug: chance.word(),
};

export const UserFactory = createUserFactory(DEFAULT_ATTRIBUTES);

This feels like the best of both worlds and doesn't require the user to pass in the input type (since we can derive it)!

[Jolg42]

There is a list of community generators here for info
https://www.prisma.io/docs/concepts/components/prisma-schema/generators

[cball]

perfect. Thanks @Jolg42.

[Jolg42]

About generator specs, the specs repository is archived & generally outdated so I can recommend this instead https://www.notion.so/prismaio/Prisma-Generators-a2cdf262207a4e9dbcd0e362dfac8dc0

[toyamarinyon]

I created factory generator based on this idea.
https://github.com/toyamarinyon/prisma-factory-generator

I made it in two days, so it's still lacking some features and documentation, but if anyone is interested in using it, I'd be happy to get feedback!

[younes0]

Awesome.
You could also check for inspiration: https://laravel.com/docs/8.x/database-testing#defining-model-factories