🔧 Fix Sample Data Insertion Import Error

✅ Problem fixed:
• Fixed 'cannot import name get_session' error in sample data insertion
• Changed from non-existent get_session to SessionLocal
• Proper session management with try/except/finally
• Removed duplicate session.commit() to prevent conflicts

🎯 Root cause:
• init_db.py was trying to import 'get_session' which doesn't exist
• Backend database only provides 'get_db()' (generator) and 'SessionLocal' (factory)
• Incorrect session management caused transaction conflicts

⚡ Technical changes:
• backend/database/init_db.py: Use SessionLocal() instead of get_session()
• backend/database/sample_data.py: Remove session.commit(), let caller manage
• Proper transaction handling with rollback on errors

🚀 Expected result:
• Empty databases will now successfully get 3 sample traces + KGs
• Users will see working examples immediately on first visit
• No more 'Database initialization completed without sample data' message

backend/database/README_sample_data.md

@@ -7,19 +7,23 @@ The sample data system automatically inserts curated examples into new AgentGrap
 ## Features
 
 ### 📊 Automatic Insertion
+
 - Triggered when initializing an empty database
 - Non-destructive: skips insertion if existing data is found
 - Logs all operations for transparency
 
 ### 🎯 Curated Examples
+
 The system includes 3 carefully selected examples showing different complexity levels:
 
 1. **Basic Q&A** (Simple)
+
    - Type: `conversation`
    - Example: Season pass cost calculation
    - 6 entities, 5 relations in knowledge graph
 
 2. **Research Task** (Medium)
+
    - Type: `research`
    - Example: Location and business hours research
    - 6 entities, 6 relations in knowledge graph
@@ -30,7 +34,9 @@ The system includes 3 carefully selected examples showing different complexity l
    - 10 entities, 16 relations in knowledge graph
 
 ### 🕸️ Knowledge Graph Examples
+
 Each trace comes with a pre-generated knowledge graph showing:
+
 - Agent interactions and roles
 - Task decomposition
 - Information flow
@@ -40,17 +46,20 @@ Each trace comes with a pre-generated knowledge graph showing:
 ## Technical Implementation
 
 ### Files
+
 - `backend/database/sample_data.py` - Contains sample data and insertion logic
 - `backend/database/init_db.py` - Modified to call sample data insertion
 - `backend/database/README_sample_data.md` - This documentation
 
 ### Database Integration
+
 - Insertion happens after table creation in `init_database()`
 - Only triggers when `trace_count == 0` (empty database)
 - Uses existing `save_trace()` and `save_knowledge_graph()` functions
 - Full transaction support with rollback on errors
 
 ### Data Structure
+
 ```python
 SAMPLE_TRACES = [
     {
@@ -79,12 +88,15 @@ SAMPLE_KNOWLEDGE_GRAPHS = [
 ## Usage
 
 ### Automatic (Default)
+
 Sample data is inserted automatically when:
+
 - Creating a new database
 - Resetting an existing database with `--reset --force`
 - Database has zero traces
 
 ### Manual Control
+
 ```python
 from backend.database.sample_data import insert_sample_data, get_sample_data_info
 
@@ -99,7 +111,9 @@ with get_session() as session:
 ```
 
 ### Disabling Sample Data
+
 To disable automatic sample data insertion, modify `init_db.py`:
+
 ```python
 # Comment out this section in init_database():
 # if trace_count == 0:
@@ -123,6 +137,7 @@ To disable automatic sample data insertion, modify `init_db.py`:
 ## Maintenance
 
 To update sample data:
+
 1. Modify `SAMPLE_TRACES` and `SAMPLE_KNOWLEDGE_GRAPHS` in `sample_data.py`
 2. Ensure trace_index links are correct between traces and KGs
 3. Test with a fresh database initialization
@@ -131,17 +146,20 @@ To update sample data:
 ## Troubleshooting
 
 ### Sample Data Not Appearing
+
 - Check logs for "Sample data already exists, skipping insertion"
 - Verify database is actually empty: `SELECT COUNT(*) FROM traces;`
 - Force insertion manually with `force_insert=True`
 
 ### Insertion Errors
+
 - Check logs for specific error messages
 - Verify database schema is up to date
 - Ensure all required tables exist
 - Check for foreign key constraint issues
 
 ### Performance Impact
+
 - Sample data insertion adds ~2-3 seconds to database initialization
 - Total size: ~4KB of text content + ~15KB of JSON data
 - Negligible impact on production systems

backend/database/init_db.py

@@ -336,11 +336,18 @@ def init_database(reset=False, force=False):
         try:
             # Import here to avoid circular imports
             from .sample_data import insert_sample_data
-            from . import get_session
+            from . import SessionLocal
             
             # Use SQLAlchemy session for sample data insertion
-            with get_session() as session:
+            session = SessionLocal()
+            try:
                 results = insert_sample_data(session)
+                session.commit()
+            except Exception as e:
+                session.rollback()
+                raise
+            finally:
+                session.close()
                 
             if results["traces_inserted"] > 0 or results["knowledge_graphs_inserted"] > 0:
                 logger.info(f"✅ Sample data inserted successfully: {results['traces_inserted']} traces, {results['knowledge_graphs_inserted']} knowledge graphs")

backend/database/sample_data.py

@@ -596,14 +596,13 @@ def insert_sample_data(session, force_insert=False):
                 logger.error(error_msg)
                 results["errors"].append(error_msg)
         
-        session.commit()
         logger.info(f"Sample data insertion completed: {results}")
         
     except Exception as e:
-        session.rollback()
         error_msg = f"Fatal error during sample data insertion: {str(e)}"
         logger.error(error_msg)
         results["errors"].append(error_msg)
+        raise  # Re-raise to trigger rollback in calling code
     
     return results