feat(receipts): implement PO-optional GRN creation with migration scripts

- Make po_id nullable in scm_grn table to allow GRN creation without Purchase Orders
- Make po_item_id nullable in scm_grn_item table for flexible item linking
- Make batch_no nullable in scm_grn_item table to support optional batch tracking
- Update ReceiptsService to generate temporary UUID for po_item_id when not provided
- Add Python migration script with asyncpg for database schema updates
- Add SQL migration script for direct database execution
- Enable warehouse receipt workflows independent of PO requirements

app/purchases/receipts/services/service.py

@@ -116,7 +116,7 @@ class ReceiptsService:
             grn_item = ScmGrnItem(
                 grn_item_id=grn_item_id,
                 grn_id=grn.grn_id,
-                po_item_id=item_data.po_item_id,  # Can be None now
+                po_item_id=item_data.po_item_id or uuid4(),  # Temporary: use dummy UUID if None
                 catalogue_id=item_data.catalogue_id,
                 sku=item_data.sku,
                 recv_qty=item_data.recv_qty,

migration_make_po_optional.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""
+Migration script to make PO optional in GRN tables.
+This allows creating GRNs without requiring a Purchase Order.
+"""
+
+import asyncio
+import asyncpg
+import os
+from dotenv import load_dotenv
+
+# Load environment variables
+load_dotenv()
+
+async def run_migration():
+    """Run the database migration to make PO fields optional"""
+    
+    # Database connection parameters
+    db_config = {
+        'host': os.getenv('POSTGRES_HOST', 'ep-sweet-surf-a1qeduoy.ap-southeast-1.aws.neon.tech'),
+        'port': int(os.getenv('POSTGRES_PORT', 5432)),
+        'database': os.getenv('POSTGRES_DB', 'cuatrolabs'),
+        'user': os.getenv('POSTGRES_USER', 'trans_owner'),
+        'password': os.getenv('POSTGRES_PASSWORD'),
+        'ssl': 'require'
+    }
+    
+    print("🔄 Starting migration: Make PO optional in GRN tables")
+    print(f"📡 Connecting to: {db_config['host']}:{db_config['port']}/{db_config['database']}")
+    
+    try:
+        # Connect to database
+        conn = await asyncpg.connect(**db_config)
+        print("✅ Connected to database")
+        
+        # Start transaction
+        async with conn.transaction():
+            print("\n📝 Executing migration steps...")
+            
+            # Step 1: Make po_id nullable in scm_grn table
+            print("1️⃣ Making po_id nullable in scm_grn table...")
+            await conn.execute("""
+                ALTER TABLE scm_grn 
+                ALTER COLUMN po_id DROP NOT NULL;
+            """)
+            print("   ✅ scm_grn.po_id is now nullable")
+            
+            # Step 2: Make po_item_id nullable in scm_grn_item table
+            print("2️⃣ Making po_item_id nullable in scm_grn_item table...")
+            await conn.execute("""
+                ALTER TABLE scm_grn_item 
+                ALTER COLUMN po_item_id DROP NOT NULL;
+            """)
+            print("   ✅ scm_grn_item.po_item_id is now nullable")
+            
+            # Step 3: Make batch_no nullable in scm_grn_item table (if not already)
+            print("3️⃣ Making batch_no nullable in scm_grn_item table...")
+            await conn.execute("""
+                ALTER TABLE scm_grn_item 
+                ALTER COLUMN batch_no DROP NOT NULL;
+            """)
+            print("   ✅ scm_grn_item.batch_no is now nullable")
+            
+            print("\n🎉 Migration completed successfully!")
+            print("📋 Summary of changes:")
+            print("   • scm_grn.po_id: NOT NULL → NULL")
+            print("   • scm_grn_item.po_item_id: NOT NULL → NULL") 
+            print("   • scm_grn_item.batch_no: NOT NULL → NULL")
+            print("\n💡 GRNs can now be created without Purchase Orders!")
+        
+        await conn.close()
+        print("🔌 Database connection closed")
+        
+    except Exception as e:
+        print(f"❌ Migration failed: {str(e)}")
+        raise
+
+if __name__ == "__main__":
+    asyncio.run(run_migration())

migration_make_po_optional.sql

@@ -0,0 +1,25 @@
+-- Migration: Make PO optional in GRN tables
+-- This allows creating GRNs without requiring a Purchase Order
+
+-- Step 1: Make po_id nullable in scm_grn table
+ALTER TABLE scm_grn 
+ALTER COLUMN po_id DROP NOT NULL;
+
+-- Step 2: Make po_item_id nullable in scm_grn_item table  
+ALTER TABLE scm_grn_item 
+ALTER COLUMN po_item_id DROP NOT NULL;
+
+-- Step 3: Make batch_no nullable in scm_grn_item table
+ALTER TABLE scm_grn_item 
+ALTER COLUMN batch_no DROP NOT NULL;
+
+-- Verify the changes
+SELECT 
+    table_name,
+    column_name,
+    is_nullable,
+    data_type
+FROM information_schema.columns 
+WHERE table_name IN ('scm_grn', 'scm_grn_item') 
+  AND column_name IN ('po_id', 'po_item_id', 'batch_no')
+ORDER BY table_name, column_name;