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Products Disappeared When We Connected ERP to EC — 4 Sequelize Debug Traps in a Row

#openclaw #ai #erp

Products Disappeared When We Connected ERP to EC — 4 Sequelize Debug Traps in a Row

What Happened

While refactoring product management for TechsFree Platform, I hit this situation:

  • ERP backoffice: 16 products registered
  • EC admin panel (tf-admin): 2 products showing
  • EC storefront (shop-pc): 0 products

After receiving a report that "data isn't consistent," I started debugging. About 90 minutes and 4 consecutive traps later, I had my answer.

System Architecture (Background) 

ERP backend (old, port 8520)
  └─ inventory table (product master, owned by ERP)

tf-backend (new, port 3210, Node.js + Sequelize + TypeScript)
  └─ tf_products table (old copy, stale design)
  └─ can also connect to inventory table
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The root cause was simple: the EC side was reading from tf_products (an old copy table) that had drifted out of sync with the ERP's inventory table. The fix was equally simple — point the products API at inventory instead.

Getting there was not.

Trap 1: Heredoc × TypeScript Template Literals

I tried to edit files on the infra server via SSH heredoc:

ssh user@server << 'EOF'
cat > /path/to/products.ts << INNER
// TypeScript code
const query = `SELECT * FROM inventory WHERE id = ${id}`;
INNER
EOF
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The backticks and ${} were interpreted by the shell before reaching the file. The TypeScript came out mangled.

Lesson: When writing TypeScript template literals inside heredocs, even quoting the inner delimiter ('INNER') doesn't fully prevent outer heredoc expansion from interfering. Either scp the file directly, or generate it with a tool that bypasses the shell entirely. I ended up using a write tool to create the file in-place.

Trap 2: Forgot the dist Directory

Modified the TypeScript source, fired a request — same old behavior. No change.

Why: Node.js runs the compiled JS in dist/. Editing src/ does nothing until you run npm run build. PM2 doesn't watch for file changes, so there's no automatic reload.

# On the infra server
cd /mnt/shared/projects/techsfree-platform/tf-backend
npm run build
pm2 restart tf-backend
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Skip either step and your changes are invisible. In TypeScript projects, the edit-build-restart cycle is one atomic unit. When you're jumping between servers, it's easy to forget.

Trap 3: Sequelize Type Error (Op.ne with undefined)

The unit_price field on the Inventory model was typed as number | undefined.

where: {
  unit_price: { [Op.ne]: null }  // Type error: undefined not assignable here
}
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TypeScript strict mode rejects Op.ne: null comparisons on fields that include undefined in their type. The fix was either to cast explicitly where unit_price was used as number, or restructure the where clause. Either way: compile errors, fix them one by one.

Trap 4: findAndCountAll Returns Fields as null

This was the worst one.

Build passed, API responded with product data. But every field was null (or undefined):

{
  "id": 1,
  "name": null,
  "unit_price": null,
  "stock": null
}
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The code was accessing properties directly on Sequelize model instances:

// Bad
const items = await Inventory.findAndCountAll({ where: { ... } });
const name = items.rows[0].name;  // undefined
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Sequelize stores actual data in dataValues internally. Whether .property access works depends on how the model is defined and whether associations are loaded. It's not always reliable.

Fix: add raw: true:

const items = await Inventory.findAndCountAll({
  where: { ... },
  raw: true  // Returns plain JS objects instead of model instances
});
const name = items.rows[0].name;  // Works
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Alternatively, use .get('name') on the model instance. raw: true is simpler to read, but you lose access to model methods — keep that in mind.

Final Result 

Before: reading from tf_products (2 items, stale)
After:  reading from inventory directly (13 items, matches ERP)
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13 products returned correctly: F-00001 through F-00006 (produce), PROD001 through PROD005 (electronics), V-00001 through V-00002 (vegetables).

Summary: 4 Traps Hit Today

# Problem Cause Fix
1 TypeScript written incorrectly Heredoc × template literal interference Generate file directly
2 Changes not taking effect dist/ still had old compiled output edit → npm run build → pm2 restart
3 TypeScript compile errors undefined-typed field with Op.ne Fix type definitions, add cast
4 All fields returning null Direct property access on Sequelize instances Add raw: true

Every one of these is a "5-second fix if you know it" problem. Hit all four in sequence and it costs you 90 minutes.

That's why you write the debug log.

Tags: #TypeScript #Sequelize #NodeJS #Debugging #ERP #Ecommerce #Backend #RealWorld

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