Prisma Class Generator

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Contents · Usage · Supported options · Per-field directives · Databases · Prisma versions · Features · Comparison with similar tools · FAQ

In a hurry? dryRun defaults to true, so the first run prints the classes to your terminal instead of writing them. Set dryRun = "false" in the generator block once the preview looks right — see Supported options.

Prisma

Prisma is a database ORM library for Node.js and TypeScript.

Prisma generates each model's type definitions directly from schema.prisma, so no additional entry classes or repository layers are required.

That works well on its own, but it runs into a limitation with frameworks like NestJS: to use @nestjs/swagger, an entity has to be defined as a class, and Prisma Client's generated types aren't classes.

This tool closes that gap — it generates a TypeScript file per model based on schema.prisma. The generated classes are formatted with prettier, using the user's prettier config file if present, so defining classes by hand is no longer necessary while schema.prisma stays the single source of truth.

Prisma Client's returned objects don't include a model's relational fields. This generator can produce two separate files per model instead — one that matches Prisma Client's own interface, and one that holds only the relational fields — by setting the separateRelationFields option to true. The default value is false.

NestJS

NestJS is a framework for building efficient, scalable Node.js server-side applications.

NestJS builds on classes and decorators as its basic structure. Defining a model as a class, as below, makes it straightforward to apply Swagger, TypeGraphQL, and similar tools through decorators — and regenerating the class whenever schema.prisma changes keeps the two in sync.

export class Company {
	@ApiProperty({ type: Number }) // swagger
	@Field((type) => Int) // TypeGraphQL
	id: number

	@ApiProperty({ type: String }) // swagger
	name: string

	@ApiProperty({ type: Boolean }) // swagger
	isUse: boolean
}

With separateRelationFields set to true, the two generated classes can be composed into a class that contains only the relations you actually want. The example below uses @nestjs/swagger's composition helpers to create a class with all of Product's own properties plus just the category relation from the generated relations class.

import { IntersectionType, PickType } from '@nestjs/swagger'
import { Product } from './product'
import { ProductRelations } from './product_relations'

export class ProductDto extends IntersectionType(
	Product,
	PickType(ProductRelations, ['category'] as const),
) {}

Usage

1. Install — as a dev dependency: it runs as part of prisma generate and the classes it writes don't import it, so it never needs to ship to production.

   npm install --save-dev prisma-class-generator
   

   yarn add --dev prisma-class-generator
   

2. Define the generator in schema.prisma

   generator prismaClassGenerator {
       provider = "prisma-class-generator"
   }
   

   This generator reads the Prisma Client generator declared in the same schema to figure out where the client lives, so make sure one is present too — either the legacy provider = "prisma-client-js" or the newer provider = "prisma-client" (default since Prisma 7). Both are supported.

3. Check the generated files

   Given these models in schema.prisma — this is the exact Product/Category/Company example from prisma/postgresql.prisma, the same schema this repo's own CI golden test runs against, so it won't drift out of sync with the real generator again:

   enum ProductType {
     A
     B
     C
   }
   
   enum ProductAnotherType {
     AA
     BB
     CC
   }
   
   model Product {
     id            Int                @id
     title         String             @db.VarChar(255)
     desc          String             @default("abc") @db.VarChar(1024)
     images        Json               @db.Json
     isShown       Boolean?           @default(false)
     stock         Int?               @default(0)
     type          ProductType
     anotherType   ProductAnotherType @default(AA)
     averageRating Float?
     categoryId    Int
     companyId     Int
     category      Category           @relation(fields: [categoryId], references: [id])
     company       Company            @relation(fields: [companyId], references: [id])
     createdAt     DateTime           @default(now()) @db.Timestamp(6)
     updatedAt     DateTime           @updatedAt @db.Timestamp(6)
   }
   
   model Category {
     id       Int       @id
     products Product[]
   }
   
   model Company {
     id                      Int       @id
     name                    String
     totalIncome             BigInt    @default(100)
     lat                     Decimal
     lng                     Decimal
     by                      Bytes
     products                Product[]
     tags                    String[]
     tagsWithEmptyDefault    String[]  @default([])
     tagsWithDefault         String[]  @default(["a", "b"])
     numTags                 Int[]
     numTagsWithEmptyDefault Int[]     @default([])
     numTagsWithDefault      Int[]     @default([1, 2])
   }
   

   these classes are generated in <PROJECT_PATH>/src/_gen/prisma-class — this is the real, unedited output of running the generator against the schema above:

   ( The generating path can be customized through output option. )

   // category.ts
   import { Product, type Product as ProductAsType } from './product'
   import { ApiProperty } from '@nestjs/swagger'
   
   export class Category {
   	@ApiProperty({ type: Number })
   	id: number
   
   	@ApiProperty({ isArray: true, type: () => Product })
   	products: ProductAsType[]
   }
   

   // company.ts
   import { Product, type Product as ProductAsType } from './product'
   import { ApiProperty } from '@nestjs/swagger'
   
   export class Company {
   	@ApiProperty({ type: Number })
   	id: number
   
   	@ApiProperty({ type: String })
   	name: string
   
   	@ApiProperty({ type: BigInt })
   	totalIncome: BigInt = BigInt(100)
   
   	@ApiProperty({ type: Number })
   	lat: number
   
   	@ApiProperty({ type: Number })
   	lng: number
   
   	@ApiProperty({ type: Buffer })
   	by: Buffer
   
   	@ApiProperty({ isArray: true, type: () => Product })
   	products: ProductAsType[]
   
   	@ApiProperty({ isArray: true, type: String })
   	tags: string[]
   
   	@ApiProperty({ isArray: true, type: String })
   	tagsWithEmptyDefault: string[] = []
   
   	@ApiProperty({ isArray: true, type: String })
   	tagsWithDefault: string[] = ['a', 'b']
   
   	@ApiProperty({ isArray: true, type: Number })
   	numTags: number[]
   
   	@ApiProperty({ isArray: true, type: Number })
   	numTagsWithEmptyDefault: number[] = []
   
   	@ApiProperty({ isArray: true, type: Number })
   	numTagsWithDefault: number[] = [1, 2]
   }
   

   // product.ts
   import { Category, type Category as CategoryAsType } from './category'
   import { Company, type Company as CompanyAsType } from './company'
   import { ProductType, ProductAnotherType } from '@prisma/client'
   import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger'
   
   export class Product {
   	@ApiProperty({ type: Number })
   	id: number
   
   	@ApiProperty({ type: String })
   	title: string
   
   	@ApiProperty({ type: String, example: 'abc' })
   	desc: string = 'abc'
   
   	@ApiProperty({ type: Object })
   	images: object
   
   	@ApiPropertyOptional({ type: Boolean, example: false })
   	isShown?: boolean = false
   
   	@ApiPropertyOptional({ type: Number, example: 0 })
   	stock?: number = 0
   
   	@ApiProperty({ enum: ProductType, enumName: 'ProductType' })
   	type: ProductType
   
   	@ApiProperty({
   		enum: ProductAnotherType,
   		enumName: 'ProductAnotherType',
   		example: ProductAnotherType.AA,
   	})
   	anotherType: ProductAnotherType = ProductAnotherType.AA
   
   	@ApiPropertyOptional({ type: Number })
   	averageRating?: number
   
   	@ApiProperty({ type: Number })
   	categoryId: number
   
   	@ApiProperty({ type: Number })
   	companyId: number
   
   	@ApiProperty({ type: () => Category })
   	category: CategoryAsType
   
   	@ApiProperty({ type: () => Company })
   	company: CompanyAsType
   
   	@ApiProperty({ type: Date })
   	createdAt: Date
   
   	@ApiProperty({ type: Date })
   	updatedAt: Date
   }
   

   Note that optional fields with a schema-level default (isShown, stock, totalIncome, the tags*/numTags* arrays above) are generated with that default value already assigned, so a new Product() starts in a valid state without every caller having to set them. And notice that relation fields (category/company/products above) import both the real class and a type ... as ...AsType alias — the field's own type annotation uses the alias to avoid a circular-import crash under emitDecoratorMetadata; see this repo's CLAUDE.md if you're curious why.

   // index.ts
   import { Product as _Product } from './product'
   import { Category as _Category } from './category'
   import { Company as _Company } from './company'
   
   export namespace PrismaModel {
   	export class Product extends _Product {}
   	export class Category extends _Category {}
   	export class Company extends _Company {}
   
   	export const extraModels = [Product, Category, Company]
   }
   

   Classes are grouped into the PrismaModel namespace and re-exported through index.ts for two reasons:

   1. Generated class names can otherwise collide with the model types Prisma itself generates.
   2. When wiring up Swagger in NestJS, extraModels can point at this one array instead of listing every generated class individually in bootstrap code.

   For example:

   // main.ts in a NestJS application
   import { PrismaModel } from './_gen/prisma-class'
   
   const document = SwaggerModule.createDocument(app, options, {
   	extraModels: [...PrismaModel.extraModels],
   })
   

   You can also disable it through the makeIndexFile option.

Supported options

Every value is written as a string in schema.prisma (dryRun = "false", not dryRun = false) — that's how Prisma passes generator config through.

Details for each:

• dryRun
  • Controls whether files are written to disk or just printed to the terminal. default value is true
    • once the printed preview looks right, set this option to false to actually write the files
• output
  • sets output path. default is '../src/_gen/prisma-class'
• useSwagger
  • generates swagger decorator (@ApiProperty/@ApiPropertyOptional from @nestjs/swagger). default value is true
    • a field's /// doc comment (minus any @directive tokens) becomes the decorator's description — see Per-field directives below for the directives themselves
    • a literal @default(...) (e.g. @default("abc"), @default(1), an enum default) becomes the decorator's example. Function-based defaults (now(), autoincrement(), dbgenerated()) and BigInt/DateTime defaults are skipped — there's no single literal worth showing
    • both are derived straight from the schema, not guessed, so they're always on when useSwagger is — no separate option
• useGraphQL
  • generates TypeGraphQL decorator (@Field from @nestjs/graphql). default value is false
• useValidation
  • generates class-validator decorators (@IsInt, @IsString, @IsOptional, @IsEnum, @IsArray, ...) based on each field's Prisma type, for use with NestJS's ValidationPipe. default value is false
    • relation and composite-type fields are intentionally left without a type-specific validator: validating one means assuming a shape for the nested payload, which the schema doesn't state. Turn on validateNestedRelations if the relation field is the payload you want validated as-is
    • DateTime fields use @IsDateString() rather than @IsDate(), so it validates the raw string a JSON request body actually contains without requiring class-transformer's @Type(() => Date) to run first
    • BigInt/Bytes/Json fields get no type-specific validator — class-validator has no direct equivalent for those
    • a field's @db.* native type sharpens the validator further when it describes a real constraint, on Prisma 6+ only (Prisma 5's DMMF doesn't expose native types at all — this silently falls back to the type-based validator above, no error): @db.Uuid/ @db.UniqueIdentifier → @IsUUID(), MongoDB's @db.ObjectId → @IsMongoId(), postgresql/cockroachdb's @db.Inet → @IsIP() (all three replace the generic @IsString()), @db.VarChar(n)/@db.Char(n)/sqlserver's N-prefixed variants/ cockroachdb's @db.String(n) → @IsString() + @MaxLength(n), MySQL's unsigned integer types → @IsInt() + @Min(0)
      • deliberately not covered: MySQL's @db.UnsignedBigInt — it maps to Prisma's BigInt scalar, and class-validator's @Min()/@Max() require typeof value === 'number', which a BigInt value never satisfies (its typeof is 'bigint') — adding it would reject every value, including valid ones
• validateNestedRelations
  • requires useValidation. Adds @ValidateNested() ({ each: true } for list relations) to relation and composite-type fields, so NestJS's ValidationPipe (with transform: true) recurses into nested payloads instead of leaving them unvalidated. default value is false
  • off by default because it's an opt-in to a specific DTO shape (see the FAQ) — turn it on if your relation fields are the nested payload you want validated as-is, not a DTO with a different nested shape
  • pulls in class-transformer's @Type(() => X) alongside @ValidateNested() — see useSerialization below, which generates the same @Type() independently of validation; the two don't double up if both are on
• makeIndexFile
  • makes index file, default value is true
• separateRelationFields
  • puts relational fields into different file for each model. This way the class will match the object returned by a Prisma query, default value is false
• makeDtoFiles
  • also generates Create<Model> and Update<Model> classes for each model, default value is false
    • they're compositions, not copies: CreateUser extends OmitType(User, [...] as const) and UpdateUser extends PartialType(CreateUser), so each field's type, Swagger metadata and validators stay declared in exactly one place (NestJS's mapped types carry all three through)
    • imported from @nestjs/swagger when useSwagger is on, otherwise from @nestjs/mapped-types
    • a field is omitted from Create only when the schema itself says the client can't supply it: a function-based @default(...) (autoincrement(), uuid(), cuid(), now(), auto(), dbgenerated(...)), @updatedAt, or a relation field. A literal default like @default(0) is kept — "there's a fallback" isn't "you may not set it" — and so is a relation's foreign-key scalar (authorId), which is the value a REST client actually posts
    • an @id without a default (e.g. id String @id) is kept too: the caller has to provide it
    • composite types (MongoDB type blocks) get no DTOs — they're embedded values, not entities with their own endpoints
    • with separateRelationFields, the DTOs compose the base class (never the *Relations one)
• clientImportPath
  • set prisma client import path manually, default value is @prisma/client
    • set this explicitly when using Prisma 7's prisma-client generator, since its output is no longer @prisma/client by default
• useNonNullableAssertions
  • Adds a ! after non-optional class fields, to avoid TypeScript strict mode's "Property has no initializer and is not definitely assigned in the constructor" warning
• preserveDefaultNullable
  • Controls how nullable fields are typed. When false (default), nullable fields are typed as undefined instead of null. When true, the field keeps Prisma's own nullable type (| null) instead.
• useUndefinedDefault
  • Assigns = undefined to fields with no default value, so every class field has an explicit initializer. default value is false
• preserveDecimal
  • Generates Decimal fields as Prisma.Decimal instead of number, avoiding precision loss for values like money. default value is false
    • only changes the field's own TS type — the swagger/graphql decorator options stay Number/Float, since Decimal has no OpenAPI/GraphQL representation of its own
• useSerialization
  • generates class-transformer's @Exclude()/@Expose() for fields marked with the /// @exclude//// @expose directives (see below), for use with NestJS's ClassSerializerInterceptor. default value is false
    • the field stays on the class (unlike /// @skip) — only the serialized JSON response drops it
    • also adds @Type(() => X) to relation and composite-type fields, independently of useValidation — without it, a ClassSerializerInterceptor/plainToInstance() call leaves a nested relation as a plain object instead of an instance of the related class, so that class's own @Exclude()/@Expose() decorators never get applied to it

Per-field directives

These are set per-field with a /// doc comment directly above the field in schema.prisma — a regular // comment won't work, since Prisma's DMMF only exposes triple-slash doc comments.

• /// @skip
  • Excludes the field entirely from the generated class (and from any relation/import it would otherwise pull in). Useful for auto-populated columns like id, createdAt, updatedAt that don't belong on a create/update DTO.

    model Product {
      id Int @id @default(autoincrement())
      /// @skip
      createdAt DateTime @default(now())
      title     String
    }
    

• /// @ApiHideProperty
  • Keeps the field on the class but adds @ApiHideProperty() (from @nestjs/swagger), hiding it from the generated OpenAPI docs. Only applies when useSwagger is on. Useful for fields like passwordHash that the class still needs at the type level but shouldn't be documented.

    model User {
      id Int @id @default(autoincrement())
      /// @ApiHideProperty
      passwordHash String
    }
    

• /// @exclude
  • Keeps the field on the class but adds class-transformer's @Exclude(), so a ClassSerializerInterceptor strips it from the actual JSON response. Only applies when useSerialization is on. Unlike @ApiHideProperty (which only hides it from docs), this changes runtime behavior — the field genuinely won't be in the response body.

    model User {
      id Int @id @default(autoincrement())
      /// @exclude
      passwordHash String
    }
    

• /// @expose
  • @exclude's counterpart, for the opposite class-transformer strategy: adds @Expose() so the field survives a plainToInstance(cls, data, { excludeExtraneousValues: true }) call, where every field is hidden by default unless explicitly marked. Only applies when useSerialization is on.

    model User {
      id Int @id @default(autoincrement())
      /// @expose
      displayName String
    }
    

Supported databases

Prisma normalizes every connector's column types down to the same DMMF scalar set, so this generator works the same way regardless of database. Verified end-to-end (and covered by golden tests in this repo) against every database Prisma ORM currently supports:

• PostgreSQL
• MySQL
• MongoDB (including composite type blocks)
• SQL Server (mssql)
• SQLite
• CockroachDB

Native-type annotations (@db.VarChar, @db.Money, @db.ObjectId, ...) never change a field's own TS type — that still comes from the DMMF scalar type (String, Int, ...), not the underlying column. On Prisma 6+ they do sharpen useValidation's output for a handful of well-known types (see useValidation above) — that's the one place native types are read at all; everywhere else they're still invisible to this generator. Two connector-level limits are worth knowing, though they're Prisma restrictions rather than anything this generator controls: SQL Server and SQLite don't support Prisma's native enum, and Prisma's Unsupported("...") escape-hatch type is excluded from the DMMF entirely (so it never reaches Prisma Client either).

Supported Prisma versions

Tested against Prisma 5, 6, and 7, including both the legacy prisma-client-js generator and the prisma-client generator that became the default in Prisma 7.

How it works?

Prisma internally represents schema metadata as a DMMF (Data Model Meta Format) object.

prisma-class-generator reads that DMMF to automate class definitions. It's declared as an additional generator in schema.prisma and runs as part of the prisma generate process.

flowchart LR
    A["schema.prisma"] -->|"prisma generate"| B["Prisma CLI"]
    B -->|"DMMF (schema metadata)"| C["prisma-class-generator"]
    C -->|"one .ts per model"| D["*.ts classes<br/>(@nestjs/swagger / class-validator / TypeGraphQL)"]

Feature

• Generates classes from Prisma model definitions
• Supports basic scalar types and relations
• Optionally generates Swagger decorators
• Optionally generates TypeGraphQL decorators
• Optionally generates class-validator decorators, sharpened further by @db.* native types on Prisma 6+ (@IsUUID(), @IsMongoId(), @IsIP(), @MaxLength(), @Min(0))
• Formats generated classes with prettier, using the user's prettier config file if present
• Per-field /// @skip, /// @ApiHideProperty, /// @exclude, and /// @expose directives
• Optionally generates class-transformer decorators (@Exclude()/@Expose() from /// @exclude//// @expose, @Type() on relation/composite fields) for use with ClassSerializerInterceptor
• preserveDecimal option to keep Decimal fields precision-safe as Prisma.Decimal
• Doc comments and literal @default(...) values become Swagger description/example
• Optional Create/Update DTO classes (makeDtoFiles), generated as NestJS mapped-type compositions so field definitions are never duplicated

Future Plan

• Support custom path, case or name per each model

---

Comparison with similar tools

A few other Prisma generators solve overlapping problems. This is meant to help you pick the right one, not to talk anyone out of the alternatives — they're good tools with a different shape.

If you want a class per model that mirrors what Prisma Client actually returns — optionally with Create/Update DTOs composed from it rather than duplicated out of it — this library is a good fit. If you'd rather have a full Create/Update/Connect DTO set with each field expanded per class, prisma-generator-nestjs-dto makes more of those decisions for you.

---

FAQ

1. Is it a CRUD generator?

No — it doesn't provide functionality like nestjs generate crud. That's out of scope for this library, which focuses on defining classes and leaves how those classes get used up to the developer. It's meant as a bridge connecting a Prisma model to an entity/DTO class, not an end-to-end code generator — a narrower scope keeps it adaptable to different projects.

2. Does it only work with NestJS?

No. It pairs particularly well with NestJS because the generated classes lean on the same class-and-decorator patterns NestJS already builds on (@nestjs/swagger, @nestjs/graphql, class-validator) — but any framework built around reflect-metadata-based class decorators can use the generated classes just as directly.

3. OK, so how do I actually build Create/Update DTOs from the generated class?

Set makeDtoFiles = "true" and they're generated for you (see the option above) — as compositions of the model class, so no field is ever declared twice:

// create_user.ts
export class CreateUser extends OmitType(User, ['id', 'createdAt', 'updatedAt'] as const) {}

// update_user.ts
export class UpdateUser extends PartialType(CreateUser) {}

The omit list comes only from things the schema states outright — a function-based @default(...), @updatedAt, or a relation field — never from guessing at field names.

If your API's create payload differs from that (an admin route that does set id, a ConnectDto-style nested write, a field you want dropped for reasons the schema doesn't express), write it by hand — the generated class is decorated with @nestjs/swagger's @ApiProperty, which is exactly what PartialType/OmitType/PickType are designed to compose, so this has always worked without any generator support:

import { OmitType, PartialType } from '@nestjs/swagger'
import { User } from './_gen/prisma-class/user'

// omit auto-generated / server-controlled fields for creation
export class CreateUserDto extends OmitType(User, ['id', 'createdAt', 'updatedAt'] as const) {}

// every field optional, for a PATCH-style update
export class UpdateUserDto extends PartialType(CreateUserDto) {}

A hand-written DTO and makeDtoFiles coexist fine — the generated CreateUser/UpdateUser are ordinary classes you can ignore, extend, or OmitType further.

4. I'm getting a decorators error (e.g. Babel's Missing plugin "decorators") when I import a generated class — what's missing?

The generated classes use TypeScript's experimental (legacy) decorators, so the project consuming them needs to support that syntax:

• Compiling with tsc: set "experimentalDecorators": true in tsconfig.json — and "emitDecoratorMetadata": true too if you rely on decorator-derived type metadata (e.g. NestJS's dependency injection, or @nestjs/swagger's type inference).
• Compiling with Babel (e.g. a Next.js or Create React App-based toolchain): add @babel/plugin-proposal-decorators with the { legacy: true } option.

A NestJS project already ships with experimentalDecorators/emitDecoratorMetadata enabled by default, so this typically only comes up when the generated classes are consumed from a non-NestJS TypeScript or Babel project.