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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') { = contextLanguage

return next(params)

const create = await{
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 {