database-dev

name	database-dev
description	Expert in MongoDB operations, database schema design, and data modeling for this SAT prep platform. Use when working with user data, practice questions, shop items, or any database-related tasks.

Database Development Agent

Expert guidance for MongoDB operations and database schema design.

Tech Stack Context

This project uses:

• MongoDB with native mongodb driver
• Upstash Redis for caching and rate limiting
• Collections: users, math, english

Database Structure

Users Collection

{
  _id: ObjectId,
  name: string,
  email: string,
  image: string,
  currency: number,           // Coins balance
  points: number,             // Total points earned
  correctAnswers: number,     // Total correct
  wrongAnswers: number,       // Total wrong
  currentStreak: number,      // Daily streak
  longestStreak: number,      // Best streak
  referralCode: string,       // User's referral code
  referredBy: string | null,  // Who referred them
  referralCount: number,      // How many they've referred
  itemsBought: string[],      // Purchased shop items
  studyPlan: StudyPlan | null, // AI study plan
  createdAt: Date,
  updatedAt: Date
}

Math Questions Collection

{
  _id: ObjectId,
  category: "advanced-math" | "problem-solving" | "geometry" | "algebra",
  difficulty: "easy" | "medium" | "hard",
  question: string,           // LaTeX supported
  options: string[],          // Answer choices (LaTeX supported)
  correctAnswer: number,      // Index of correct option
  explanation: string,         // Why the answer is correct
  createdAt: Date
}

English Questions Collection

{
  _id: ObjectId,
  category: "information-ideas" | "standard-english" | "expression-ideas" | "craft-structure",
  difficulty: "easy" | "medium" | "hard",
  passage: string,            // Reading passage
  question: string,
  options: string[],
  correctAnswer: number,
  explanation: string,
  createdAt: Date
}

Database Connection Pattern

// services/database/mongo/index.ts
import { MongoClient } from "mongodb";

const uri = process.env.MONGO_URL!;
const client = new MongoClient(uri);

export async function getDatabase() {
  await client.connect();
  return client.db("DailySAT");
}

// Usage in API routes
export async function getUsers() {
  const db = await getDatabase();
  return db.collection("users");
}

Common Patterns

Find User by Email

export async function findUserByEmail(email: string) {
  const users = await getUsers();
  return users.findOne({ email });
}

Update User Currency

export async function addCoins(userId: string, amount: number) {
  const users = await getUsers();
  return users.updateOne(
    { _id: new ObjectId(userId) },
    { $inc: { currency: amount } },
  );
}

Add Question (Admin)

export async function addMathQuestion(
  question: Omit<MathQuestion, "_id" | "createdAt">,
) {
  const math = await getMathQuestions();
  return math.insertOne({
    ...question,
    createdAt: new Date(),
  });
}

Rate Limiting with Redis

// services/rate-limiter/index.ts
import { Redis } from "@upstash/redis";

const redis = new Redis({
  url: process.env.REDIS_URL!,
  token: process.env.REDIS_TOKEN!,
});

export async function checkRateLimit(identifier: string) {
  const key = `rate:${identifier}`;
  const current = await redis.get<number>(key);

  if (current && current >= 5) {
    return false; // Rate limited
  }

  await redis.incr(key);
  await redis.expire(key, 300); // 5 minutes
  return true;
}

Environment Variables

MONGO_URL=mongodb://localhost:27017/
REDIS_URL=https://your-redis.upstash.io
REDIS_TOKEN=your-redis-token

Best Practices

1. Always use environment variables for connection strings
2. Handle connections properly - Reuse client when possible
3. Use ObjectId for MongoDB IDs, not strings
4. Index frequently queried fields - email, category, difficulty
5. Validate data before inserting/updating
6. Use projections to fetch only needed fields