1_schemas.js

// This file contains example schemas that will be used throughout the tutorial
// Note: MongoDB is schema-less by default, but defining schemas helps in maintaining data consistency

// User Schema
const userSchema = {
    // _id will be automatically added by MongoDB
    username: String,         // Required, unique
    email: String,           // Required, unique
    age: Number,             // Optional
    created_at: Date,        // Automatically set
    address: {               // Nested document example
        street: String,
        city: String,
        country: String
    },
    interests: [String]      // Array example
};

// Product Schema (for e-commerce example)
const productSchema = {
    name: String,            // Required
    price: Number,           // Required
    description: String,
    category: String,
    in_stock: Boolean,
    tags: [String],
    specifications: Object   // Flexible object for various product specs
};

// Order Schema (showing relationships)
const orderSchema = {
    user_id: 'ObjectId',     // Reference to User collection
    products: [{            // Array of embedded documents
        product_id: 'ObjectId', // Reference to Product collection
        quantity: Number,
        price: Number
    }],
    total_amount: Number,
    status: String,         // e.g., 'pending', 'completed', 'cancelled'
    order_date: Date,
    shipping_address: Object
};

// Comments Schema (for demonstrating nested relationships and arrays)
const commentSchema = {
    user_id: 'ObjectId',
    content: String,
    post_id: 'ObjectId',
    likes: Number,
    replies: [{
        user_id: 'ObjectId',
        content: String,
        created_at: Date
    }],
    created_at: Date
};

// Export schemas for reference in other files
module.exports = {
    userSchema,
    productSchema,
    orderSchema,
    commentSchema
};

/* Schema Usage Notes:
1. These schemas are for reference only - MongoDB doesn't enforce them by default
2. For schema validation, you can use:
   - MongoDB Schema Validation
   - Mongoose (ODM for MongoDB)
   - Application-level validation

3. MongoDB data types include:
   - String
   - Number
   - Date
   - Boolean
   - ObjectId
   - Array
   - Object (for nested documents)
   - Binary Data
   - Null
   
4. Best Practices:
   - Use appropriate data types
   - Consider indexing requirements
   - Plan for data growth
   - Choose between embedding and referencing based on use case
*/