Posted on Dec 9, 2021

Use factory to simplify prisma seed.

Prisma provides the ability to seed data. Once configured, it is convenient to create a seed with the script npx prisma db seed.
However, when you register data with the seed script, you need to enter all the parameters, which is a tedious aspect of preparation.

Let's consider the following table as an example

model User { id Int @id @default(autoincrement()) email String @unique userName String @unique lastName String firstName String school String @@map(name: "users") }

In this case, the seed script looks like this

// create bob const bob = await prisma.user.create({ create: { email: "bob@prisma.io", username: "bob", lastName: "curry", firstName: "bob", school: "demo", }, }); // create Chance const chance = await prisma.user.create({ create: { email: "chance@prisma.io", username: "chance", lastName: "weber", firstName: "chance", school: "demo", }, }); : : :

It may be enough, but it seemed a bit redundant to me. It is tedious to enter the parameters every time.

As a solution, I implemented the factory function using a library such as faker.js, but it's hard to maintain the factory function every time the number of tables or items increases.

So I thought that one of the ideal development flows would be to have a factory function created using npx prisma migrate dev or npx prisma generate, which is executed when a table is added or an item is added in Prisma.

Prisma has a good mechanism called generator, so I used it to create a generator called prisma-factory-generator that creates a factory from Prisma's Scheme.

https://github.com/toyamarinyon/prisma-factory-generator

Using this, we can rewrite the previous seed script to look like this.

// For the sake of clarity, I have omitted imports // and grammatical descriptions. const bob = await createUser({ userName: 'bob' }) const chance = await createUser({ userName: 'chance' })

I think Prisma-factory-generator is useful not only for seeding but also for test code, so please try it if you like.
If you have a case where it doesn't work, please send an issue to

https://github.com/toyamarinyon/prisma-factory-generator/issues