使用 Nestjs、RAG、Prisma 和 Gemini API 构建上下文感知的待办事项列表

<code class="bash">nest new todo-app
cd todo-app</code>

<code class="bash">rm src/app.controller.* src/app.service.* src/app.module.ts</code>

<code class="bash">npm install prisma @prisma/client @google/generative-ai dotenv pg</code>

<code class="bash">npx prisma init</code>

<code>DATABASE_URL="postgresql://<用户名>:<密码>@localhost:5432/<数据库名>?schema=public"
GEMINI_API_KEY="<你的Gemini API密钥>"</code>

<code class="prisma">generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["postgresqlextensions"]
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
  extensions = ["pgvector"]
}

model Task {
  id        Int      @id @default(autoincrement())
  title     String
  content   String
  embedding Unsupported("vector(1536)")
}</code>

<code class="bash">npx prisma migrate dev --name init</code>

<code class="typescript">// src/prisma/prisma.module.ts
import { Module } from '@nestjs/common';
import { PrismaService } from './prisma.service';

@Module({
  providers: [PrismaService],
  exports: [PrismaService],
})
export class PrismaModule {}

// src/prisma/prisma.service.ts
import { Injectable, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
import { PrismaClient } from '@prisma/client';

@Injectable()
export class PrismaService extends PrismaClient implements OnModuleInit, OnModuleDestroy {
  async onModuleInit() {
    await this.$connect();
  }

  async onModuleDestroy() {
    await this.$disconnect();
  }
}</code>

<code class="typescript">// src/app.module.ts
import { Module } from '@nestjs/common';
import { PrismaModule } from './prisma/prisma.module';
import { TasksModule } from './tasks/tasks.module';

@Module({
  imports: [PrismaModule, TasksModule],
})
export class AppModule {}</code>

<code class="bash">nest generate module tasks
nest generate service tasks
nest generate controller tasks</code>

<code class="typescript">// src/tasks/tasks.service.ts
import { Injectable } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { Task } from '@prisma/client';
import { GeminiService } from '../gemini/gemini.service';

@Injectable()
export class TasksService {
  constructor(private prisma: PrismaService, private geminiService: GeminiService) {}

  async createTask(title: string, content: string): Promise<Task> {
    const embedding = await this.geminiService.getEmbedding(`${title} ${content}`);
    return this.prisma.task.create({
      data: { title, content, embedding },
    });
  }

  async getTasks(): Promise<Task[]> {
    return this.prisma.task.findMany();
  }

  async findSimilarTasks(embedding: number[], limit = 5): Promise<any[]> {
    const embeddingStr = `[${embedding.join(',')}]`;
    return this.prisma.$queryRaw`
      SELECT *, embedding <-> ${embeddingStr}::vector AS distance
      FROM "Task"
      ORDER BY distance
      LIMIT ${limit};
    `;
  }
}</code>

<code class="typescript">// src/tasks/tasks.controller.ts
import { Controller, Post, Get, Body } from '@nestjs/common';
import { TasksService } from './tasks.service';

@Controller('tasks')
export class TasksController {
  constructor(private tasksService: TasksService) {}

  @Post()
  async createTask(@Body('title') title: string, @Body('content') content: string) {
    return this.tasksService.createTask(title, content);
  }

  @Get()
  async getTasks() {
    return this.tasksService.getTasks();
  }
}</code>

<code class="typescript">// src/gemini/gemini.service.ts
import { Injectable } from '@nestjs/common';
import { GenerativeLanguageServiceClient } from '@google/generative-ai';

@Injectable()
export class GeminiService {
  private client: GenerativeLanguageServiceClient;

  constructor() {
    this.client = new GenerativeLanguageServiceClient({
      apiKey: process.env.GEMINI_API_KEY,
    });
  }

  async getEmbedding(text: string): Promise<number[]> {
    const result = await this.client.embedText({
      model: 'models/text-embedding-001',
      content: text,
    });
    return result.embedding;
  }
}</code>