Integrating OpenAI with NestJS — Step by Step

Integrating OpenAI's powerful APIs with NestJS can supercharge your applications with AI capabilities. This guide will walk you through the complete integration process.

Setting Up the Project

First, let's create a new NestJS project and install the necessary dependencies:

npm install @nestjs/common @nestjs/core @nestjs/platform-express
npm install openai
npm install @nestjs/config

Environment Configuration

Create a .env file with your OpenAI API key:

OPENAI_API_KEY=your_api_key_here
OPENAI_ORGANIZATION=your_org_id_here

Creating the OpenAI Service

Create a dedicated service for OpenAI integration:

import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import OpenAI from 'openai';

@Injectable()
export class OpenAIService {
  private openai: OpenAI;

  constructor(private configService: ConfigService) {
    this.openai = new OpenAI({
      apiKey: this.configService.get('OPENAI_API_KEY'),
      organization: this.configService.get('OPENAI_ORGANIZATION'),
    });
  }

  async generateText(prompt: string): Promise {
    try {
      const completion = await this.openai.chat.completions.create({
        model: 'gpt-3.5-turbo',
        messages: [{ role: 'user', content: prompt }],
        max_tokens: 1000,
        temperature: 0.7,
      });

      return completion.choices[0]?.message?.content || '';
    } catch (error) {
      throw new Error(`OpenAI API error: ${error.message}`);
    }
  }
}

Rate Limiting and Error Handling

Implement proper rate limiting and error handling:

• Use Redis for rate limiting
• Implement exponential backoff for retries
• Add comprehensive error logging
• Set up monitoring and alerts

Best Practices

• Always validate input before sending to OpenAI
• Implement caching for frequently requested content
• Use streaming for long responses
• Monitor API usage and costs

Conclusion

With proper setup and error handling, OpenAI integration can add powerful AI capabilities to your NestJS applications. Remember to monitor usage and implement appropriate safeguards.