Advanced type safety

The generated code for Prisma Client contains several helpful types and utilities that you can use to make your application more type-safe. This page describes patterns for leveraging them.

Importing generated types

You can import the Prisma namespace and use dot notation to access types and utilities. The following example shows how to import the Prisma namespace and use it to access and use the Prisma.UserSelect generated type:

import { Prisma } from '@prisma/client'

// Build 'select' object
const userEmail: Prisma.UserSelect = {
  email: true,
}

// Use select object
const createUser = await prisma.user.create({
  data: {
    email: 'bob@prisma.io',
  },
  select: userEmail,
})

See also: Using the Prisma.UserCreateInput generated type

What are generated types?

Generated types are TypeScript types that are derived from your models. You can use them to create typed objects that you pass into top-level methods like prisma.user.create(...) or prisma.user.update(...), or options such as select or include.

For example, select accepts an object of type UserSelect. Its object properties match those that are supported by select statements according to the model.

The first tab below shows the UserSelect generated type and how each property on the object has a type annotation. The second tab shows the resulting schema model.

type Prisma.UserSelect = {
    id?: boolean | undefined;
    email?: boolean | undefined;
    name?: boolean | undefined;
    posts?: boolean | Prisma.PostFindManyArgs | undefined;
    profile?: boolean | Prisma.ProfileArgs | undefined;
}

In TypeScript the concept of type annotations is when you declare a variable and add a type annotation to describe the type of the variable. See the below example.

const myAge: number = 37
const myName: string = 'Rich'

Both of these variable declarations have been given a type annotation to specify what primitive type they are, number and string respectively. Most of the time this kind of annotation is not needed as TypeScript will infer the type of the variable based on how its initialized. In the above example myAge was initialized with a number so TypeScript guesses that it should be typed as a number.

Going back to the UserSelect type, if you were to use dot notation on the created object userEmail, you would have access to all of the fields on the User model that can be interacted with using a select statement.

model User {
  id      Int      @id @default(autoincrement())
  email   String   @unique
  name    String?
  posts   Post[]
  profile Profile?
}

import { Prisma } from '@prisma/client'

const userEmail: Prisma.UserSelect = {
  email: true,
}

// properties available on the typed object
userEmail.id
userEmail.email
userEmail.name
userEmail.posts
userEmail.profile

In the same mould, you can type an object with an include generated type then your object would have access to those properties on which you can use an include statement.

import { Prisma } from '@prisma/client'

const userPosts: Prisma.UserInclude = {
  posts: true,
}

// properties available on the typed object
userPosts.posts
userPosts.profile

See the model query options reference for more information about the different types available.

model Post {
  id       Int     @id @default(autoincrement())
  title    String  @db.VarChar(255)
  content  String?
  author   User    @relation(fields: [authorId], references: [id])
  authorId Int
}

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

type PostUncheckedCreateInput = {
  id?: number
  title: string
  content?: string | null
  authorId: number
}

type PostCreateInput = {
  title: string
  content?: string | null
  author: UserCreateNestedOneWithoutPostsInput
}

type UserCreateNestedOneWithoutPostsInput = {
  create?: XOR<
    UserCreateWithoutPostsInput,
    UserUncheckedCreateWithoutPostsInput
  >
  connectOrCreate?: UserCreateOrConnectWithoutPostsInput
  connect?: UserWhereUniqueInput
}