prisma-class-validator-generator

Prisma Class Validator Generator

🏗️ Prisma Class Validator Generator

Automatically generate TypeScript class-validator models from your Prisma schema
Create type-safe validation classes with decorators from your database models

Quick Start • Examples • Features • Contributing

💖 Support This Project

If this tool helps you build better applications, please consider supporting its development:

Your sponsorship helps maintain and improve this project. Thank you! 🙏

✨ Features

• 🏗️ Auto-generation - Automatically generates TypeScript models with class-validator decorators
• 🔧 Prisma 6 support - Full compatibility with the latest Prisma features and types
• 🎯 Type safety - Perfect TypeScript integration with proper type inference
• 📝 Smart decorators - Intelligent mapping of Prisma types to class-validator decorators
• 🔄 Incremental updates - Regenerates only when schema changes
• 🚀 Zero config - Works out of the box with sensible defaults
• 🛡️ Production ready - Battle-tested with comprehensive test coverage
• 📦 Lightweight - Minimal dependencies and fast generation

🚀 Quick Start

Installation

# npm
npm install prisma-class-validator-generator

# yarn
yarn add prisma-class-validator-generator

# pnpm
pnpm add prisma-class-validator-generator

Basic Setup

• Add the generator to your Prisma schema:

generator class_validator {
  provider = "prisma-class-validator-generator"
  output   = "./generated"  // optional, defaults to ./generated
}

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

model Post {
  id        Int      @id @default(autoincrement())
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
  title     String
  content   String?
  published Boolean  @default(false)
  viewCount Int      @default(0)
  author    User?    @relation(fields: [authorId], references: [id])
  authorId  Int?
  rating    Float
}

• Generate your models:

npx prisma generate

• Use the generated classes:

import { User } from './generated/models';
import { validate } from 'class-validator';

const user = new User();
user.id = 1;
user.email = '[e-mail]';
user.name = 'John Doe';

const errors = await validate(user);
if (errors.length > 0) {
  console.log('Validation failed:', errors);
} else {
  console.log('User is valid!');
}

🎯 Generated Output

The generator creates TypeScript classes with appropriate class-validator decorators:

User.model.ts

import { IsInt, IsDefined, IsString, IsOptional } from "class-validator";
import { Post } from "./Post.model";

export class User {
    @IsDefined()
    @IsInt()
    id!: number;

    @IsDefined()
    @IsString()
    email!: string;

    @IsOptional()
    @IsString()
    name?: string | null;

    @IsDefined()
    posts!: Post[];
}

Post.model.ts

import { IsInt, IsDefined, IsDate, IsString, IsOptional, IsBoolean, IsNumber } from "class-validator";
import { User } from "./User.model";

export class Post {
    @IsDefined()
    @IsInt()
    id!: number;

    @IsDefined()
    @IsDate()
    createdAt!: Date;

    @IsDefined()
    @IsDate()
    updatedAt!: Date;

    @IsDefined()
    @IsString()
    title!: string;

    @IsOptional()
    @IsString()
    content?: string | null;

    @IsDefined()
    @IsBoolean()
    published!: boolean;

    @IsDefined()
    @IsInt()
    viewCount!: number;

    @IsOptional()
    author?: User | null;

    @IsOptional()
    @IsInt()
    authorId?: number | null;

    @IsDefined()
    @IsNumber()
    rating!: number;
}

🔧 Configuration Options

Customize the generator behavior:

generator class_validator {
  provider               = "prisma-class-validator-generator"
  output                 = "./src/models"           // Output directory
  swagger                = "true"                   // Add Swagger decorators
  separateRelationFields = "true"                   // Split base/relation classes
}

Available Options

Option	Type	Default	Description
output	string	"./generated"	Output directory for generated models
swagger	string	"false"	Add NestJS @ApiProperty decorators for Swagger docs
separateRelationFields	string	"false"	Generate separate base and relation classes for flexible DTOs

Swagger Support (swagger = "true")

Automatically generates NestJS Swagger decorators alongside class-validator decorators:

export class User {
  @IsDefined()
  @ApiProperty({ example: 'Generated by autoincrement', type: "integer" })
  @IsInt()
  id!: number;

  @IsDefined()
  @ApiProperty({ type: "string" })
  @IsString()
  email!: string;

  @IsOptional()
  @ApiProperty({ type: "string", required: false })
  @IsString()
  name?: string | null;
}

Relation Field Splitting (separateRelationFields = "true")

Perfect for NestJS DTOs - generates separate classes for maximum flexibility:

• UserBase.model.ts - Only scalar fields with validation decorators
• UserRelations.model.ts - Only relation fields
• User.model.ts - Combined class extending UserBase

This enables powerful NestJS patterns:

// Create DTO without relations using PickType
export class CreateUserDto extends PickType(UserBase, ['email', 'name']) {}

// Update DTO with partial fields
export class UpdateUserDto extends PartialType(UserBase) {}

// Full model with relations for responses
export class UserResponseDto extends User {}

📚 Advanced Usage

Complex Schema Example

enum Role {
  USER
  ADMIN
  MODERATOR
}

model User {
  id        String   @id @default(cuid())
  email     String   @unique
  name      String?
  role      Role     @default(USER)
  profile   Profile?
  posts     Post[]
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
}

model Profile {
  id     String @id @default(cuid())
  bio    String?
  avatar Bytes?
  user   User   @relation(fields: [userId], references: [id])
  userId String @unique
}

model Post {
  id        String    @id @default(cuid())
  title     String
  content   String?
  published Boolean   @default(false)
  tags      String[]
  metadata  Json?
  author    User      @relation(fields: [authorId], references: [id])
  authorId  String
  createdAt DateTime  @default(now())
  updatedAt DateTime  @updatedAt
}

Generated Enum

export enum Role {
  USER = "USER",
  ADMIN = "ADMIN",
  MODERATOR = "MODERATOR",
}

Generated Models with Advanced Types

import { IsString, IsDefined, IsEmail, IsOptional, IsEnum, IsDate } from "class-validator";
import { Role } from "../enums";
import { Profile } from "./Profile.model";
import { Post } from "./Post.model";

export class User {
    @IsDefined()
    @IsString()
    id!: string;

    @IsDefined()
    @IsEmail()
    email!: string;

    @IsOptional()
    @IsString()
    name?: string | null;

    @IsDefined()
    @IsEnum(Role)
    role!: Role;

    @IsOptional()
    profile?: Profile | null;

    @IsDefined()
    posts!: Post[];

    @IsDefined()
    @IsDate()
    createdAt!: Date;

    @IsDefined()
    @IsDate()
    updatedAt!: Date;
}

🧪 Testing

The generator includes comprehensive tests covering:

• Basic model generation
• Complex schemas with relations
• Enum generation
• Edge cases and error handling
• TypeScript compilation

Run tests:

npm test           # Run tests in watch mode
npm run test:ci    # Run tests once with coverage
npm run test:coverage  # Generate coverage report

🔍 Type Mapping

The generator intelligently maps Prisma types to class-validator decorators:

Prisma Type	TypeScript Type	Class Validator Decorator
String	string	@IsString()
Int	number	@IsInt()
Float	number	@IsNumber()
Boolean	boolean	@IsBoolean()
DateTime	Date	@IsDate()
Bytes	Uint8Array	@IsDefined()
Json	any	@IsDefined()
String[]	string[]	@IsArray()
Enum	EnumType	@IsEnum(EnumType)
Optional fields	type | null	@IsOptional()
Required fields	type	@IsDefined()

🤝 Contributing

We welcome contributions! Please see our Contributing Guide for details.

Development Setup

git clone https://github.com/omar-dulaimi/prisma-class-validator-generator.git
cd prisma-class-validator-generator
npm install
npm run build
npm test

Common Development Commands

npm run build         # Compile TypeScript
npm run start         # Build and run Prisma generate
npm test              # Run tests in watch mode
npm run test:ci       # Run tests with coverage
npm run format        # Format code with Prettier

📖 API Reference

Generator Configuration

The generator accepts the following configuration in your schema.prisma:

generator class_validator {
  provider = "prisma-class-validator-generator"
  output   = "./generated"    // Optional: output directory
}

Generated File Structure

generated/
├── models/
│   ├── User.model.ts
│   ├── Post.model.ts
│   └── index.ts
├── enums/
│   ├── Role.ts
│   └── index.ts
└── index.ts

🐛 Troubleshooting

Common Issues

• Generator not found: Ensure you've installed the package as a dependency
• Output directory errors: Check that the parent directory exists
• Import errors: Make sure class-validator is installed in your project

Debug Mode

Enable debug logging by setting the DEBUG environment variable:

DEBUG=prisma:generator npx prisma generate

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Built for the amazing Prisma ecosystem
• Powered by class-validator for robust validation
• Uses ts-morph for TypeScript AST manipulation

Made with ❤️ by Omar Dulaimi

⭐ Star us on GitHub • 🐛 Report Issues • 💬 Discussions