Middleware sample: session data

The following example sets the language field of each Post to the context language (taken, for example, from session state):

const prisma = new PrismaClient()

const contextLanguage = 'en-us' // Session state

prisma.$use(async (params, next) => {
  if (params.model == 'Post' && params.action == 'create') {
    params.args.data.language = contextLanguage
  }

  return next(params)
})

const create = await prisma.post.create({
  data: {
    title: 'My post in English',
  },
})

The example is based on the following sample schema:

generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "mysql"
  url      = env("DATABASE_URL")
}

model Post {
  authorId  Int?
  content   String?
  id        Int     @id @default(autoincrement())
  published Boolean @default(false)
  title     String
  user      User?   @relation(fields: [authorId], references: [id])
  language  String?

  @@index([authorId], name: "authorId")
}

model User {
  email           String  @unique
  id              Int     @id @default(autoincrement())
  name            String?
  posts           Post[]
  extendedProfile Json?
  role            Role    @default(USER)
}

enum Role {
  ADMIN
  USER
  MODERATOR
}