Prisma Generator NestJS DTO

Generates ConnectDTO, CreateDTO, UpdateDTO, and Entity classes from Prisma schema with smart merge capabilities to preserve custom fields and decorators.

Table of Contents

1. What is it?
2. Installation & Usage
3. Configuration
4. Annotations
5. Smart Merge System
6. Examples
7. License

What is it?

Generates ConnectDTO, CreateDTO, UpdateDTO, and Entity classes for models in your Prisma Schema. This is useful for OpenAPI in NestJS applications and GraphQL resources. NestJS Swagger requires input parameters in controllers to be described through classes because it leverages TypeScript's emitted metadata and Reflection to generate OpenAPI spec components.

These classes can also be used with NestJS ValidationPipe and Serialization.

What's New in v2.1.2?

🚀 Latest Release with Advanced Features

• Smart Merge System v2: Complete rewrite using ts-morph for more reliable AST manipulation and enhanced code preservation
• Advanced Import Management: Intelligent import deduplication and organization with conflict resolution
• Enhanced Decorator Strategy: Improved decorator configuration system with better type safety and validation
• Modular Template System: Refactored template helpers for better maintainability and customization
• Performance Optimizations: Faster generation with optimized file processing and caching
• Improved Error Handling: Better error messages and debugging capabilities
• Extended Field Classifiers: More precise field analysis and categorization
• TypeScript 5.8+ Support: Full compatibility with latest TypeScript features
• Fix generated index.ts: Index was empited every time it was rewritten

Key Features

• Smart Merge System v2: Advanced AST-based merging that preserves custom fields, decorators, and code structure
• Full Annotation Support: Use Prisma comments to control DTO generation with advanced field classification
• Flexible Configuration: Extensive customization options for naming, output structure, and behavior
• Type Safety: Full TypeScript 5.8+ support with enhanced type inference and validation
• NestJS Integration: Seamless integration with Swagger, validation, serialization, and GraphQL
• Custom Decorator System: Define and use custom decorators with intelligent import management
• Performance Optimized: Fast generation with intelligent caching and parallel processing
• Modular Architecture: Clean, maintainable codebase with extensive test coverage

Installation & Usage

npm install --save-dev @weverson_na/prisma-generator-nestjs-dto

Add the generator to your schema.prisma:

generator nestjsDto {
  provider = "prisma-generator-nestjs-dto"
  output   = "../src/generated/nestjs-dto"
}

Then run:

npx prisma generate

Configuration

All parameters are optional:

• output: (default: "../src/generated/nestjs-dto") - Output path relative to your schema.prisma file
• outputToNestJsResourceStructure: (default: "false") - Organize DTOs in NestJS CRUD generator structure
• exportRelationModifierClasses: (default: "true") - Export extra classes for relationship operations
• reExport: (default: "false") - Create index.ts files for every folder
• createDtoPrefix: (default: "Create") - Prefix for CreateDTO classes
• updateDtoPrefix: (default: "Update") - Prefix for UpdateDTO classes
• dtoSuffix: (default: "Dto") - Suffix for DTO classes
• entityPrefix: (default: "") - Prefix for Entity classes
• entitySuffix: (default: "") - Suffix for Entity classes
• fileNamingStyle: (default: "camel") - File naming style: "camel", "pascal", "kebab", or "snake"
• classValidation: (default: "false") - Add class-validator decorators
• addExposePropertyDecorator: (default: "false") - Add @Expose() decorators for serialization

Example with all options:

generator nestjsDto {
  provider                        = "prisma-generator-nestjs-dto"
  output                          = "../src/generated/nestjs-dto"
  outputToNestJsResourceStructure = "true"
  exportRelationModifierClasses   = "true"
  reExport                        = "true"
  createDtoPrefix                 = "Create"
  updateDtoPrefix                 = "Update"
  dtoSuffix                       = "Dto"
  entityPrefix                    = ""
  entitySuffix                    = "Entity"
  fileNamingStyle                 = "kebab"
  classValidation                 = "true"
  addExposePropertyDecorator      = "true"
}

Annotations

Use triple-slash comments in your Prisma schema to control DTO generation:

model Post {
  /// @IsDate()
  /// @DtoCreateOptional  
  /// @DtoUpdateHidden
  createdAt DateTime @default(now())
  
  /// @DtoReadOnly
  id String @id @default(uuid())
  
  /// @ApiProperty({ description: "Post title", minLength: 1, maxLength: 100 })
  /// @IsNotEmpty()
  /// @MaxLength(100)
  title String
}

Available Annotations

Field Visibility:

• @DtoReadOnly - Omits field from CreateDTO and UpdateDTO
• @DtoEntityHidden - Omits field from Entity
• @DtoCreateOptional - Makes field optional in CreateDTO
• @DtoUpdateOptional - Makes field optional in UpdateDTO

Relations:

• @DtoRelationRequired - Marks relation as required in Entity
• @DtoRelationCanCreateOnCreate - Allow creating related records in CreateDTO
• @DtoRelationCanConnectOnCreate - Allow connecting to existing records in CreateDTO
• @DtoRelationCanCreateOnUpdate - Allow creating related records in UpdateDTO
• @DtoRelationCanConnectOnUpdate - Allow connecting to existing records in UpdateDTO

Swagger/OpenAPI:

• @ApiProperty - Pass options directly to Swagger decorator

Validation:

• Any class-validator decorator (e.g., @IsEmail(), @MinLength(3), @IsOptional())

Smart Merge System

The Smart Merge System v2 uses advanced AST manipulation via ts-morph to preserve your custom fields and decorators when regenerating DTOs. This allows you to:

1. Add custom fields to generated DTOs that persist across regenerations
2. Add custom decorators to any field with intelligent import management
3. Modify generated properties without losing changes on subsequent generations
4. Keep custom imports with automatic deduplication and conflict resolution
5. Preserve complex TypeScript constructs like interfaces, enums, and type aliases

Technical Improvements in v2.1.0

• AST-Based Merging: Uses TypeScript compiler API for more reliable code analysis and generation
• Intelligent Import Management: Automatically handles import conflicts and deduplication
• Enhanced Field Classification: Better detection of generated vs custom fields
• Performance Optimizations: Faster processing with intelligent caching strategies
• Better Error Recovery: Improved handling of malformed code and syntax errors

How it works

Generated fields are marked with // @generated from prisma schema:

export class CreateUserDto {
  // @generated from prisma schema
  @ApiProperty()
  name: string;

  // @generated from prisma schema  
  @ApiProperty()
  @IsEmail()
  email: string;

  // Custom field - preserved during regeneration
  @ApiProperty({ description: 'Custom validation field' })
  @IsOptional()
  customField?: string;
}

Custom Decorator Configuration

Create a decorator-config.json file to define custom decorators with advanced import mapping:

[
  {
    "importPath": "@example/core",
    "names": ["Component", "Injectable", "Pipe"]
  },
  {
    "importPath": "class-validator",
    "names": ["IsUUID", "IsEnum", "ValidateNested"]
  },
  {
    "importPath": "@nestjs/swagger",
    "names": ["ApiProperty", "ApiHideProperty"]
  }
]

Then reference it in your schema:

generator nestjsDto {
  provider = "prisma-generator-nestjs-dto"
  decoratorConfigPath = "./decorator-config.json"
}

Advanced Configuration Options

generator nestjsDto {
  provider                        = "prisma-generator-nestjs-dto"
  output                          = "../src/generated/nestjs-dto"
  outputToNestJsResourceStructure = "true"
  exportRelationModifierClasses   = "true"
  reExport                        = "true"
  createDtoPrefix                 = "Create"
  updateDtoPrefix                 = "Update"
  dtoSuffix                       = "Dto"
  entityPrefix                    = ""
  entitySuffix                    = "Entity"
  fileNamingStyle                 = "kebab"
  classValidation                 = "true"
  addExposePropertyDecorator      = "true"
  decoratorConfigPath             = "./decorator-config.json"
}

Troubleshooting

Q: My custom decorators are not being imported correctly
A: Make sure you have created a decorator-config.json file and referenced it in your Prisma schema with decoratorConfigPath. The decorators must be defined in the config file to be recognized.

Q: Custom fields are not being preserved
A: Ensure your custom fields don't have the comment // @generated from prisma schema. Only fields with this marker are replaced during regeneration.

Q: Generation fails with import errors
A: Check that all custom decorators in your decorator-config.json point to valid packages. Install missing dependencies with npm install.

Q: Performance issues with large schemas
A: Enable optimization features in v2.1.0 by setting optimizeImports="true" and enableAdvancedMerging="true" in your generator configuration.

Q: TypeScript compilation errors after generation
A: Ensure you're using TypeScript 5.8+ and that all custom types are properly defined. Set preserveCustomTypes="true" to maintain custom type definitions.

Migration from v2.0.x to v2.1.0

The v2.1.0 release is backward compatible, but you can take advantage of new features:

1. Update your package: npm update @weverson_na/prisma-generator-nestjs-dto
2. Regenerate your DTOs: npx prisma generate
3. Review generated code for improved import management and performance

Examples

Basic Prisma Schema

generator nestjsDto {
  provider = "prisma-generator-nestjs-dto"
  output = "../src/generated"
}

model User {
  /// @DtoReadOnly
  id        String   @id @default(uuid())
  
  /// @ApiProperty({ description: "User's email address" })
  /// @IsEmail()
  email     String   @unique
  
  /// @ApiProperty({ minLength: 2, maxLength: 50 })
  /// @IsNotEmpty()
  name      String
  
  /// @DtoCreateOptional
  /// @DtoUpdateOptional
  createdAt DateTime @default(now())
  
  posts     Post[]
}

model Post {
  id       String @id @default(uuid())
  
  /// @ApiProperty({ minLength: 1, maxLength: 100 })
  title    String
  
  content  String
  
  /// @DtoRelationRequired
  /// @DtoRelationCanConnectOnCreate
  author   User   @relation(fields: [authorId], references: [id])
  authorId String
}

Generated Output

CreateUserDto:

import { ApiProperty } from '@nestjs/swagger';
import { IsEmail, IsNotEmpty } from 'class-validator';

export class CreateUserDto {
  // @generated from prisma schema
  @ApiProperty({ description: "User's email address" })
  @IsEmail()
  email: string;

  // @generated from prisma schema
  @ApiProperty({ minLength: 2, maxLength: 50 })
  @IsNotEmpty()
  name: string;

  // @generated from prisma schema
  createdAt?: Date;
}

CreatePostDto:

import { ApiProperty } from '@nestjs/swagger';
import { ConnectUserDto } from '../user/dto/connect-user.dto';

export class CreatePostRelationInputDto {
  connect: ConnectUserDto;
}

export class CreatePostDto {
  // @generated from prisma schema
  @ApiProperty({ minLength: 1, maxLength: 100 })
  title: string;

  // @generated from prisma schema
  content: string;

  // @generated from prisma schema
  author: CreatePostRelationInputDto;
}

Smart Merge System Example

Add custom fields that will be preserved during regeneration:

// Before regeneration
export class CreateUserDto {
  // @generated from prisma schema
  @ApiProperty()
  email: string;

  // @generated from prisma schema
  @ApiProperty()
  name: string;

  // Custom field - will be preserved
  @ApiProperty({ description: 'Terms acceptance' })
  @IsBoolean()
  acceptTerms: boolean;

  // Custom validation
  @ApiProperty({ description: 'Password confirmation' })
  @IsString()
  @MinLength(8)
  passwordConfirmation: string;
}

// After running npx prisma generate - custom fields are preserved!
export class CreateUserDto {
  // @generated from prisma schema  
  @ApiProperty()
  email: string;

  // @generated from prisma schema
  @ApiProperty()
  name: string;

  // Custom field - preserved during regeneration
  @ApiProperty({ description: 'Terms acceptance' })
  @IsBoolean() 
  acceptTerms: boolean;

  // Custom validation - preserved during regeneration
  @ApiProperty({ description: 'Password confirmation' })
  @IsString()
  @MinLength(8)
  passwordConfirmation: string;
}

License

All files are released under the Apache License 2.0.

Contributing

We welcome contributions! Please feel free to:

• Report issues
• Submit feature requests
• Contribute code improvements

Development

# Clone the repository
git clone https://github.com/WeversonNA/prisma-generator-nestjs-dto.git

# Install dependencies
npm install

# Build the project
npm run build

# Run tests with coverage
npm test

# Run tests in watch mode
npm run test:watch

# Format code
npm run format

# Lint code
npm run lint

# Clean generated files
npm run cleanup:generated

# Test with a Prisma schema
npm run generate

Architecture Overview

The project follows a modular architecture with clear separation of concerns:

• src/generators/: Core generation logic for DTOs and entities
• src/commands/: Smart merge system and content processing
• src/generators/compute-model-params/: Parameter computation for different DTO types
• src/generators/decorators/: Decorator strategy and configuration processing
• src/generators/template-helpers/: Template utilities and code generation helpers
• src/generators/helpers/: Utility functions and import management

Acknowledgments

This project builds upon the excellent foundation provided by the original @vegardit/prisma-generator-nestjs-dto project.