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@mcereal/nestjsdb2

IBM DB2 Module for NestJS

The @mcereal/nestjs package is a powerful and flexible TypeScript library that integrates IBM DB2 database capabilities into NestJS applications. This package provides decorators, services, and utility functions to handle common database operations, connection management, caching, error handling, and transaction management, specifically tailored for IBM DB2 environments.

This package it under active development and is not yet ready for production use. Please use with caution and report any issues or bugs you encounter.

Table of Contents

• Features
• Installation
• Getting Started
• Configuration
• Usage
  • Importing Db2Module
  • Database Operations
  • Using Db2Module
  • Query Execution
    • Basic Query Execution
    • Batch Operations
    • Transaction Management
    • ORM Support
    • Query Builder
  • Decorators
  • Error Handling
  • Health Checks
• Examples
• Security
• Contributing
• License

Features

• Easy Integration: Seamlessly integrate IBM DB2 databases into NestJS applications.
• Typed Configuration: TypeScript-based configuration options for better type safety and IDE support.
• Connection Management: Supports connection pooling, failover, and connection state monitoring.
• Query Builder: A fluent API for building SQL queries with support for subqueries, parameterized queries, and more.
• Transaction Management: Built-in support for transactions with beginTransaction, commitTransaction, and rollbackTransaction.
• Batch Operations: Execute multiple queries in a single batch operation for improved performance.
• Decorators: Custom decorators to enforce connection state checks and cache results.
• Health Checks: Support for implementing health checks using NestJS Terminus.
• ORM Support: Lightweight ORM-like interface for defining schemas and models.

Installation

npm install @mcereal/nestjsdb2 --save

Note: The @mcereal/nestjsdb2 package relies on the ibm_db package, which requires Rosetta 2 to run on Apple Silicon Macs. Please ensure Rosetta 2 is installed on your system. You can install Rosetta 2 by running:

softwareupdate --install-rosetta --agree-to-license

Getting Started

To get started, import the Db2Module into your NestJS application and configure it using the provided options.

import { Module } from '@nestjs/common';
import { Db2Module } from '@mcereal/nestjsdb2';

@Module({
  imports: [
    Db2Module.forRoot({
      auth: {
        authType: 'password',
        username: 'db2user',
        password: 'password',
      },
      host: 'localhost',
      port: 50000,
      database: 'sampledb',
      useTls: false,
      retry: {
        maxReconnectAttempts: 5,
        reconnectInterval: 3000,
      },
      queryTimeout: 10000, // in milliseconds
    }),
  ],
})
export class AppModule {}

Configuration

The Db2Module can be configured either synchronously or asynchronously:

Synchronous Configuration

import { Module } from '@nestjs/common';
import { Db2Module } from '@mcereal/nestjsdb2';

@Module({
  imports: [
    Db2Module.forRoot({
      auth: {
        authType: 'password',
        username: 'db2user',
        password: 'password',
      },
      host: 'localhost',
      port: 50000,
      database: 'sampledb',
      useTls: false,
      cacheEnabled: true,
      retry: {
        maxReconnectAttempts: 5,
        reconnectInterval: 3000,
      },
      queryTimeout: 10000,
    }),
  ],
})
export class AppModule {}

Asynchronous Configuration

import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { Db2Module } from '@mcereal/nestjsdb2';

@Module({
  imports: [
    ConfigModule.forRoot({
      isGlobal: true,
    }),
    Db2Module.forRootAsync({
      imports: [ConfigModule],
      useFactory: async (configService: ConfigService) => ({
        auth: {
          authType: 'password',
          username: configService.get<string>('DB_USER'),
          password: configService.get<string>('DB_PASS'),
        },
        host: configService.get<string>('DB_HOST'),
        port: configService.get<number>('DB_PORT'),
        useTls: configService.get<boolean>('DB2_SSL_CONNECTION'),
        database: configService.get<string>('DB_NAME'),
        sslCertificatePath: configService.get<string>('DB_SSL_CERT_PATH'),
        retry: {
          maxReconnectAttempts: configService.get<number>('DB_RETRY_MAX') || 5,
          reconnectInterval:
            configService.get<number>('DB_RETRY_INTERVAL') || 3000,
        },
        queryTimeout: configService.get<number>('DB_QUERY_TIMEOUT') || 10000,
      }),
      inject: [ConfigService],
    }),
  ],
})
export class AppModule {}

Usage

Importing Db2Module

Ensure that the Db2Module is imported and configured in your root module (AppModule).

import { Module } from '@nestjs/common';
import { Db2Module } from '@mcereal/nestjsdb2';

@Module({
  imports: [
    Db2Module.forRoot({
      auth: {
        authType: 'password',
        username: 'db2user',
        password: 'password',
      },
      host: 'localhost',
      port: 50000,
      database: 'sampledb',
      useTls: false,
      cacheEnabled: true,
    }),
  ],
})
export class AppModule {}

Database Operations

Basic Query Execution

The query method executes a SQL query and returns the result as an array of objects:

const result = await this.db2Service.query('SELECT * FROM users');

Batch Operations

The batch method executes multiple queries in a single batch operation:

const queries = [
  { sql: 'INSERT INTO users (name) VALUES (?)', params: ['Alice
  { sql: 'INSERT INTO users (name) VALUES (?)', params: ['Bob'] },
];

const results = await this.db2Service.batch(queries);

Transaction Management

The beginTransaction, commitTransaction, and rollbackTransaction methods provide support for transactions:

await this.db2Service.beginTransaction();
await this.db2Service.query('INSERT INTO users (name) VALUES (?)', ['Alice']);
await this.db2Service.commitTransaction();

Query Builder

The QueryBuilder class provides a fluent API for building SQL queries with support for subqueries, parameterized queries, and more.

Create a new Query builder by providing the table name and an instance of th Db2Client class.

import { QueryBuilder } from '@mcereal/nestjsdb2';

const queryBuilder = new QueryBuilder('users', this.db2Service);

const result = await queryBuilder
  .select(['id', 'name'])
  .where('name', '=', 'Alice')
  .orderBy('created_at', 'DESC')
  .limit(10)
  .execute();

console.log(result);

Decorators

The @Transaction, @Connection, and `` decorators can be used to enforce connection state checks and cache results:

import { Transaction, Connection, Query, Param } from '@mcereal/nestjsdb2';

@Injectable()
export class UserService {
  @Transaction()
  async createUser(name: string) {
    await this.db2Service.query('INSERT INTO users (name) VALUES (?)', [name]);
  }

  @Connection()
  async getUserData(userId: string) {
    return this.db2Service.query('SELECT * FROM users WHERE id = ?', [userId]);
  }

  @Query('SELECT * FROM users WHERE id = ?')
  async getUserData(@Param('id') userId: string) {
    return this.db2Service.query('SELECT * FROM users WHERE id = ?', [userId]);

}

ORM Support

The @mcereal/nestjsdb2 package provides a lightweight ORM-like inrerface for working with DB2. You can define schemas using the Schema class and model classes using the Model class.

1. First, define an entity class using the @Entity decorator, and define the schema using the Schema class:

import { Schema, Model } from '@mcereal/nestjsdb2';
import { Entity, Column, PrimaryKey } from '@mcereal/nestjsdb2';

@Entity({
  entityType: 'table',
  name: 'users',
})
export class User {
  @PrimaryKey()
  id!: string;

  @Column()
  name!: string;

  @Column()
  email!: string;
}

export const UserSchema = new Schema([User]);

const UserModel = new Model('users', UserSchema);

2. Register the Schema and Model classes in the module configuration as providers:

Db2Module.forRoot({
  auth: {
    authType: 'password',
    host: 'localhost',
    port: 50000,
    database: 'sampledb',
    useTls: false,
  },
  providers: [
    {
      provide: 'UserModel',
      useValue: UserModel,
    },
  ],
});

3. Use Db2Module.forFeature to register the Schema and Model classes in a feature module:

@Module({
  imports: [
    Db2Module.forFeature({
      auth: {
        authType: 'password',
        host: 'localhost',
        port: 50000,
        database: 'sampledb',
        useTls: false,
      },
      providers: [
        {
          provide: 'UserModel',
          useValue: UserModel,
        },
      ],
    }),
  ],
})

4. Use the UserModel class to perform CRUD operations on the users table:

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

@Injectable()
export class UserService {
  constructor(@Inject('UserModel') private userModel: Model<UserModel>) {}

  async createUser(name: string, email: string) {
    return this.userModel.insert({ name, email });
  }

  async getUserById(id: string) {
    return this.userModel.findOne({ id });
  }

  async updateUser(id: string, name: string, email: string) {
    return this.userModel.update({ id }, { name, email });
  }

  async deleteUser(id: string) {
    return this.userModel.delete({ id });
  }
}

Error Handling

The @mcereal/nestjsdb2 package provides detailed error messages and stack traces for common database errors. You can import multiple error types like Db2Error, Db2ConnectionError, Db2QueryError, and Db2TransactionError to handle specific error scenarios:

import {
  Db2Error,
  Db2ConnectionError,
  Db2QueryError,
  Db2TransactionError,
} from '@mcereal/nestjsdb2';

try {
  await this.db2Service.query('SELECT * FROM non_existent_table');
} catch (error) {
  if (error instanceof Db2QueryError) {
    console.error('Query error:', error.message);
  } else if (error instanceof Db2ConnectionError) {
    console.error('Connection error:', error.message);
  } else if (error instanceof Db2TransactionError) {
    console.error('Transaction error:', error.message);
  } else if (error instanceof Db2Error) {
    console.error('DB2 error:', error.message);
  } else {
    console.error('Unknown error:', error.message);
  }
}

Health Checks

You can implement health checks for your NestJS application using the TerminusModule and the Db2HealthIndicator:

import { Module } from '@nestjs/common';
import { TerminusModule } from '@nestjs/terminus';
import { Db2HealthIndicator } from '@mcereal/nestjsdb2';

@Module({
  imports: [
    TerminusModule.forRoot({
      healthChecks: {
        db2: () => Db2HealthIndicator.pingCheck('db2'),
      },
    }),
  ],
})
export class HealthModule {}

Examples

You can find examples of how to use the @mcereal/nestjsdb2 package in the examples directory. This directory contains sample applications that demonstrate various features of the package, including basic query execution, batch operations, transaction management, and ORM support. To run the examples, follow the instructions in the examples/README.md file.

Security

The @mcereal/nestjsdb2 package follows best practices for security, including:

• Secure Connections: Supports TLS encryption for secure communication with the database.
• Parameterized Queries: Encourages the use of parameterized queries to prevent SQL injection attacks.
• Error Handling: Provides detailed error messages and stack traces for common database errors.
• Health Checks: Supports implementing health checks to monitor the database connection status.

Contributing

Contributions are welcome! Please read our contributing guidelines to get started.

License

This project is licensed under the terms of the MIT License.