CONTROLLER_MIGRATION_GUIDE.md

🔧 Controller Migration Guide - Use getAutoModels(req)

Problem

All controllers must use connection-scoped models (forMaster/forTenant) instead of direct imports.

Solution Pattern

BEFORE (❌ WRONG)

// productController.js
const Product = require("../models/productModels");

exports.createProduct = async (req, res) => {
  const product = await Product.create(req.body); // ❌ Uses WRONG connection
  res.json(product);
};

AFTER (✅ CORRECT)

// productController.js
const { getAutoModels } = require("../utils/SaaS/autoModelInitializer");

exports.createProduct = async (req, res) => {
  const { Product } = getAutoModels(req); // ✅ Auto-detects correct connection
  const product = await Product.create(req.body);
  res.json(product);
};

---

Migration Steps

Step 1: Add Import

// Add at top of controller
const { getAutoModels } = require("../utils/SaaS/autoModelInitializer");

Step 2: Remove Old Model Imports

// ❌ REMOVE these:
const Product = require("../models/productModels");
const Category = require("../models/categoryModels");
const Brand = require("../models/brandModels");
// etc.

Step 3: Replace in Each Function

// ❌ OLD:
exports.getAllProducts = async (req, res) => {
  const products = await Product.find();
};

// ✅ NEW:
exports.getAllProducts = async (req, res) => {
  const { Product } = getAutoModels(req);
  const products = await Product.find();
};

Step 4: For Multiple Models

// ✅ Can destructure multiple models
exports.createProduct = async (req, res) => {
  const { Product, Category, Brand } = getAutoModels(req);
  
  const category = await Category.findById(req.body.categoryId);
  const brand = await Brand.findById(req.body.brandId);
  
  const product = await Product.create({
    name: req.body.name,
    category: req.body.categoryId,
    brand: req.body.brandId,
  });
};

---

Controllers to Update (Priority Order)

🔴 CRITICAL (Most Used)

1. productController.js - Product CRUD
2. categoryController.js - Category CRUD
3. purchaseController.js - Purchase CRUD
4. salesController.js - Sales CRUD
5. CustomerInvoiceController.js - Invoice CRUD

🟡 HIGH (Frequently Used)

6. supplierModel.js - Supplier CRUD
7. customerController.js - Customer CRUD (already working?)
8. brandController.js - Brand CRUD
9. posSaleController.js - POS Sales

🟢 MEDIUM (Regularly Used)

10. warehouseControllers.js
11. stockController.js
12. invoiceSettingsController.js
13. creditNoteController.js
14. debitNoteController.js

---

Search & Replace Commands

Find all model imports in a file:

grep -n "const.*require.*models" productController.js

Find all Product/Category/Brand usage:

grep -n "Product\.\|Category\.\|Brand\." productController.js

---

Common CRUD Patterns

Create

const { Product, Category } = getAutoModels(req);

const product = await Product.create({
  name: req.body.name,
  category: req.body.categoryId,
  ...
});

Read (Find & FindById)

const { Product } = getAutoModels(req);

const product = await Product.findById(id);
const products = await Product.find({ status: "Active" });
const product = await Product.findOne({ name: "xyz" });

Update

const { Product } = getAutoModels(req);

const product = await Product.findByIdAndUpdate(
  id,
  { name: req.body.name },
  { new: true }
);

Delete

const { Product } = getAutoModels(req);

await Product.findByIdAndDelete(id);

Aggregation

const { Product } = getAutoModels(req);

const results = await Product.aggregate([
  { $match: { status: "Active" } },
  { $group: { _id: "$category", count: { $sum: 1 } } },
]);

---

Testing Each Controller

Test Pattern

# 1. Login as tenant user (get token)
curl -X POST http://localhost:5000/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{
    "email": "tenant@company.com",
    "password": "password"
  }'

# 2. Create with token
curl -X POST http://localhost:5000/api/products \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{
    "productName": "Test Product",
    "category": "...",
    "price": 100
  }'

# 3. Verify data  is in TENANT database only, not master

---

Error Handling

If getAutoModels(req) Fails

try {
  const { Product } = getAutoModels(req);
  // Use Product...
} catch (error) {
  console.error("Model resolution failed:", error.message);
  return res.status(500).json({
    error: "Database context not available",
    message: error.message
  });
}

---

Batch Update Script

For rapid migration, run this in each controller:

1. Add import at line 1:

   const { getAutoModels } = require("../utils/SaaS/autoModelInitializer");

2. Find each export function

3. Add this line as first line of function:

   const { Product, Category, Brand, ... } = getAutoModels(req);

4. Delete old const Product = require(...) imports

---

Verification Checklist

• getAutoModels imported in controller
• All model constants removed from top-level imports
• Each function gets models from getAutoModels(req)
• All Product/Category/Brand/.etc usage goes through Models
• No mongoose.model() direct calls
• Auth middleware provides req.db
• Test create, read, update, delete
• Verify data isolation (tenant only sees own data)

---

Example: Full Product Controller Migration

Before

const Product = require("../models/productModels");
const Category = require("../models/ categoryModels");

exports.createProduct = async (req, res) => {
  const product = await Product.create(req.body);
  res.json(product);
};

exports.getAllProducts = async (req, res) => {
  const products = await Product.find();
  res.json(products);
};

After

const { getAutoModels } = require("../utils/SaaS/autoModelInitializer");

exports.createProduct = async (req, res) => {
  const { Product, Category } = getAutoModels(req);
  const product = await Product.create(req.body);
  res.json(product);
};

exports.getAllProducts = async (req, res) => {
  const { Product } = getAutoModels(req);
  const products = await Product.find();
  res.json(products);
};

---

Migration Timeline

• Phase 1 (Immediate): Update 5 critical controllers
• Phase 2 (1-2 hours): Update 4 high-priority controllers
• Phase 3 (Next session): Update remaining controllers
• Phase 4 (Final): Test all CRUD operations across all modules

---

Support

If a controller fails after migration:

1. Check if getAutoModels returns the model
2. Verify auth middleware sets req.db
3. Ensure model has forTenant/forMaster factories
4. Check console for specific error messages