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 {