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tessl install github:giuseppe-trisciuoglio/developer-kit --skill nestjs

github.com/giuseppe-trisciuoglio/developer-kit

Comprehensive NestJS framework guide with Drizzle ORM integration. Use when building NestJS applications, setting up APIs, implementing authentication, working with databases, or integrating Drizzle ORM. Covers controllers, providers, modules, middleware, guards, interceptors, testing, microservices, GraphQL, and database patterns.

Review Score

78%

Validation Score

14/16

Implementation Score

57%

Activation Score

100%

NestJS Framework with Drizzle ORM

When to Use

Building REST APIs or GraphQL servers with NestJS
Setting up authentication and authorization
Implementing middleware, guards, or interceptors
Working with databases (TypeORM, Drizzle ORM)
Creating microservices architecture
Writing unit and integration tests
Setting up OpenAPI/Swagger documentation

Core Architecture

Module Structure

import { Module } from '@nestjs/common';

@Module({
  imports: [/* other modules */],
  controllers: [/* controllers */],
  providers: [/* providers */],
  exports: [/* exported providers */],
})
export class FeatureModule {}

Controller Pattern

import { Controller, Get, Post, Body, Param, Query } from '@nestjs/common';

@Controller('users')
export class UsersController {
  @Get()
  findAll(@Query() query: any) {
    return 'This returns all users';
  }

  @Get(':id')
  findOne(@Param('id') id: string) {
    return `This returns user #${id}`;
  }

  @Post()
  create(@Body() createUserDto: any) {
    return 'This creates a user';
  }
}

Service with Dependency Injection

import { Injectable } from '@nestjs/common';

@Injectable()
export class UsersService {
  constructor(/* inject dependencies */) {}

  findAll() {
    return 'Users service logic';
  }
}

Database Integration with Drizzle

Setup with Drizzle ORM

Installation

# Using npm
npm install drizzle-orm pg
npm install -D drizzle-kit tsx @types/pg

# Using yarn
yarn add drizzle-orm pg
yarn add -D drizzle-kit tsx @types/pg

Configuration

// drizzle.config.ts
import 'dotenv/config';
import { defineConfig } from 'drizzle-kit';

export default defineConfig({
  out: './drizzle',
  schema: './src/db/schema.ts',
  dialect: 'postgresql',
  dbCredentials: {
    url: process.env.DATABASE_URL!,
  },
});

Database Schema

// src/db/schema.ts
import { pgTable, serial, text, timestamp } from 'drizzle-orm/pg-core';

export const users = pgTable('users', {
  id: serial('id').primaryKey(),
  name: text('name').notNull(),
  email: text('email').notNull().unique(),
  createdAt: timestamp('created_at').defaultNow(),
});

Database Service

// src/db/database.service.ts
import { Injectable } from '@nestjs/common';
import { drizzle } from 'drizzle-orm/node-postgres';
import { Pool } from 'pg';
import * as schema from './schema';

@Injectable()
export class DatabaseService {
  private db: ReturnType<typeof drizzle>;

  constructor() {
    const pool = new Pool({
      connectionString: process.env.DATABASE_URL,
    });
    this.db = drizzle(pool, { schema });
  }

  get database() {
    return this.db;
  }
}

User Repository with Drizzle

// src/users/user.repository.ts
import { Injectable } from '@nestjs/common';
import { DatabaseService } from '../db/database.service';
import { users } from '../db/schema';
import { eq } from 'drizzle-orm';

@Injectable()
export class UserRepository {
  constructor(private db: DatabaseService) {}

  async findAll() {
    return this.db.database.select().from(users);
  }

  async findOne(id: number) {
    const result = await this.db.database
      .select()
      .from(users)
      .where(eq(users.id, id))
      .limit(1);
    return result[0];
  }

  async create(data: typeof users.$inferInsert) {
    const result = await this.db.database
      .insert(users)
      .values(data)
      .returning();
    return result[0];
  }

  async update(id: number, data: Partial<typeof users.$inferInsert>) {
    const result = await this.db.database
      .update(users)
      .set(data)
      .where(eq(users.id, id))
      .returning();
    return result[0];
  }

  async remove(id: number) {
    const result = await this.db.database
      .delete(users)
      .where(eq(users.id, id))
      .returning();
    return result[0];
  }
}

Complete User Module

// src/users/users.module.ts
import { Module } from '@nestjs/common';
import { UsersController } from './users.controller';
import { UsersService } from './users.service';
import { UserRepository } from './user.repository';
import { DatabaseService } from '../db/database.service';

@Module({
  controllers: [UsersController],
  providers: [UsersService, UserRepository, DatabaseService],
  exports: [UsersService],
})
export class UsersModule {}

User Service Implementation

// src/users/users.service.ts
import { Injectable } from '@nestjs/common';
import { UserRepository } from './user.repository';
import { User } from './interfaces/user.interface';

@Injectable()
export class UsersService {
  constructor(private userRepository: UserRepository) {}

  async findAll(): Promise<User[]> {
    return this.userRepository.findAll();
  }

  async findOne(id: number): Promise<User> {
    const user = await this.userRepository.findOne(id);
    if (!user) {
      throw new Error('User not found');
    }
    return user;
  }

  async create(userData: Partial<User>): Promise<User> {
    return this.userRepository.create(userData);
  }

  async update(id: number, userData: Partial<User>): Promise<User> {
    await this.findOne(id); // Verify user exists
    return this.userRepository.update(id, userData);
  }

  async remove(id: number): Promise<User> {
    await this.findOne(id); // Verify user exists
    return this.userRepository.remove(id);
  }
}

Authentication & Authorization

JWT Authentication Guard

import { Injectable, CanActivate, ExecutionContext } from '@nestjs/common';
import { JwtService } from '@nestjs/jwt';

@Injectable()
export class JwtAuthGuard implements CanActivate {
  constructor(private jwtService: JwtService) {}

  canActivate(context: ExecutionContext) {
    const request = context.switchToHttp().getRequest();
    const token = request.headers.authorization?.split(' ')[1];

    if (!token) {
      return false;
    }

    try {
      const decoded = this.jwtService.verify(token);
      request.user = decoded;
      return true;
    } catch {
      return false;
    }
  }
}

Roles-Based Guard

import { Injectable, CanActivate, ExecutionContext } from '@nestjs/common';
import { Reflector } from '@nestjs/core';

@Injectable()
export class RolesGuard implements CanActivate {
  constructor(private reflector: Reflector) {}

  canActivate(context: ExecutionContext): boolean {
    const requiredRoles = this.reflector.get<string[]>('roles', context.getHandler());
    if (!requiredRoles) {
      return true;
    }

    const { user } = context.switchToHttp().getRequest();
    return requiredRoles.some((role) => user.roles?.includes(role));
  }
}

Validation with Pipes

Validation Pipe

import { PipeTransform, Injectable, ArgumentMetadata, BadRequestException } from '@nestjs/common';
import { validate } from 'class-validator';
import { plainToClass } from 'class-transformer';

@Injectable()
export class ValidationPipe implements PipeTransform {
  async transform(value: any, { metatype }: ArgumentMetadata) {
    if (!metatype || !this.toValidate(metatype)) {
      return value;
    }

    const object = plainToClass(metatype, value);
    const errors = await validate(object);

    if (errors.length > 0) {
      throw new BadRequestException(errors);
    }

    return value;
  }

  private toValidate(metatype: Function): boolean {
    const types: Function[] = [String, Boolean, Number, Array, Object];
    return !types.includes(metatype);
  }
}

Exception Handling

Global Exception Filter

import { ExceptionFilter, Catch, ArgumentsHost, HttpException } from '@nestjs/common';
import { Request, Response } from 'express';

@Catch(HttpException)
export class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: HttpException, host: ArgumentsHost) {
    const ctx = host.switchToHttp();
    const response = ctx.getResponse<Response>();
    const request = ctx.getRequest<Request>();
    const status = exception.getStatus();

    response.status(status).json({
      statusCode: status,
      timestamp: new Date().toISOString(),
      path: request.url,
      message: exception.message,
    });
  }
}

Testing Patterns

Unit Testing Services

import { Test, TestingModule } from '@nestjs/testing';
import { UsersService } from './users.service';
import { UserRepository } from './user.repository';

describe('UsersService', () => {
  let service: UsersService;
  let repository: jest.Mocked<UserRepository>;

  beforeEach(async () => {
    const mockRepository = {
      findAll: jest.fn(),
      findOne: jest.fn(),
      create: jest.fn(),
      update: jest.fn(),
      remove: jest.fn(),
    } as any;

    const module: TestingModule = await Test.createTestingModule({
      providers: [
        UsersService,
        {
          provide: UserRepository,
          useValue: mockRepository,
        },
      ],
    }).compile();

    service = module.get<UsersService>(UsersService);
    repository = module.get(UserRepository);
  });

  it('should return all users', async () => {
    const expectedUsers = [{ id: 1, name: 'John', email: 'john@example.com' }];
    repository.findAll.mockResolvedValue(expectedUsers);

    const result = await service.findAll();
    expect(result).toEqual(expectedUsers);
    expect(repository.findAll).toHaveBeenCalled();
  });
});

E2E Testing with Drizzle

import { Test, TestingModule } from '@nestjs/testing';
import { INestApplication } from '@nestjs/common';
import * as request from 'supertest';
import { AppModule } from './../src/app.module';
import { DatabaseService } from '../src/db/database.service';
import { drizzle } from 'drizzle-orm/node-postgres';
import { migrate } from 'drizzle-node-postgres/migrator';
import { migrate as drizzleMigrate } from 'drizzle-orm/node-postgres/migrator';

describe('UsersController (e2e)', () => {
  let app: INestApplication;
  let db: DatabaseService;

  beforeAll(async () => {
    const moduleFixture: TestingModule = await Test.createTestingModule({
      imports: [AppModule],
    }).compile();

    app = moduleFixture.createNestApplication();
    db = moduleFixture.get<DatabaseService>(DatabaseService);

    // Run migrations
    await drizzleMigrate(db.database, { migrationsFolder: './drizzle' });

    await app.init();
  });

  afterAll(async () => {
    await app.close();
  });

  beforeEach(async () => {
    // Clean database
    await db.database.delete(users).execute();
  });

  it('/users (POST)', () => {
    const createUserDto = {
      name: 'Test User',
      email: 'test@example.com',
    };

    return request(app.getHttpServer())
      .post('/users')
      .send(createUserDto)
      .expect(201)
      .expect((res) => {
        expect(res.body).toMatchObject(createUserDto);
        expect(res.body).toHaveProperty('id');
      });
  });

  it('/users (GET)', async () => {
    // First create a user
    await db.database.insert(users).values({
      name: 'Test User',
      email: 'test@example.com',
    });

    return request(app.getHttpServer())
      .get('/users')
      .expect(200)
      .expect((res) => {
        expect(Array.isArray(res.body)).toBe(true);
        expect(res.body).toHaveLength(1);
      });
  });
});

Migrations with Drizzle

Generating Migrations

npx drizzle-kit generate

Running Migrations

// src/migrations/migration.service.ts
import { Injectable } from '@nestjs/common';
import { migrate } from 'drizzle-orm/node-postgres/migrator';
import { DatabaseService } from '../db/database.service';

@Injectable()
export class MigrationService {
  constructor(private db: DatabaseService) {}

  async runMigrations() {
    try {
      await migrate(this.db.database, { migrationsFolder: './drizzle' });
      console.log('Migrations completed successfully');
    } catch (error) {
      console.error('Migration failed:', error);
      throw error;
    }
  }
}

Configuration Management

Environment Configuration

// src/config/configuration.ts
export default () => ({
  database: {
    url: process.env.DATABASE_URL,
  },
  jwt: {
    secret: process.env.JWT_SECRET || 'default-secret',
    expiresIn: process.env.JWT_EXPIRES_IN || '24h',
  },
  app: {
    port: parseInt(process.env.PORT, 10) || 3000,
  },
});

Advanced Patterns

Custom Decorators

import { createParamDecorator, ExecutionContext } from '@nestjs/common';

export const User = createParamDecorator(
  (data: string, ctx: ExecutionContext) => {
    const request = ctx.switchToHttp().getRequest();
    const user = request.user;

    return data ? user?.[data] : user;
  },
);

Interceptors for Logging

import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common';
import { Observable } from 'rxjs';
import { tap } from 'rxjs/operators';

@Injectable()
export class LoggingInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    const request = context.switchToHttp().getRequest();
    const { method, url } = request;
    const now = Date.now();

    console.log(`[${method}] ${url} - Start`);

    return next
      .handle()
      .pipe(
        tap(() => console.log(`[${method}] ${url} - End ${Date.now() - now}ms`)),
      );
  }
}

Microservices

TCP Microservice

// main.ts
import { NestFactory } from '@nestjs/core';
import { Transport, MicroserviceOptions } from '@nestjs/microservices';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.createMicroservice<MicroserviceOptions>(
    AppModule,
    {
      transport: Transport.TCP,
      options: {
        host: 'localhost',
        port: 8877,
      },
    },
  );
  await app.listen();
}
bootstrap();

GraphQL Integration

GraphQL Resolver with Drizzle

import { Resolver, Query, Mutation, Args } from '@nestjs/graphql';
import { UserRepository } from './user.repository';

@Resolver(() => User)
export class UsersResolver {
  constructor(private userRepository: UserRepository) {}

  @Query(() => [User])
  async users() {
    return this.userRepository.findAll();
  }

  @Mutation(() => User)
  async createUser(@Args('input') input: CreateUserInput) {
    return this.userRepository.create(input);
  }
}

Best Practices

Always use constructor injection - Never use property injection
Use DTOs for data transfer - Define interfaces for request/response
Implement proper error handling - Use exception filters
Validate all inputs - Use validation pipes
Keep modules focused - Single responsibility principle
Use environment variables - Never hardcode credentials
Write comprehensive tests - Unit and integration tests
Use transactions for complex operations - Maintain data consistency
Implement proper logging - Use interceptors for cross-cutting concerns
Use type safety - Leverage TypeScript features

Common Patterns with Drizzle

Transactions

async transferFunds(fromId: number, toId: number, amount: number) {
  return this.db.database.transaction(async (tx) => {
    // Debit from account
    await tx
      .update(accounts)
      .set({ balance: sql`${accounts.balance} - ${amount}` })
      .where(eq(accounts.id, fromId));

    // Credit to account
    await tx
      .update(accounts)
      .set({ balance: sql`${accounts.balance} + ${amount}` })
      .where(eq(accounts.id, toId));
  });
}

Soft Deletes

export const users = pgTable('users', {
  id: serial('id').primaryKey(),
  name: text('name').notNull(),
  email: text('email').notNull().unique(),
  deletedAt: timestamp('deleted_at'),
});

async softDelete(id: number) {
  return this.db.database
    .update(users)
    .set({ deletedAt: new Date() })
    .where(eq(users.id, id));
}

Complex Queries with Relations

async getUsersWithPosts() {
  return this.db.database
    .select()
    .from(users)
    .leftJoin(posts, eq(posts.userId, users.id));
}