#!/usr/bin/env python3
"""
Diagnostic script to demonstrate the Neo4j transaction scope issue and fix
"""
import asyncio
# This script demonstrates the problem and solution without needing database access
async def demonstrate_problem():
"""Show the problematic pattern that causes transaction scope errors"""
print("=== PROBLEMATIC PATTERN ===")
print("""
# This is what was causing the error:
result = await session.execute_write(
lambda tx: tx.run(query, params)
)
# At this point, the lambda has returned and the transaction is closed
records = await result.values() # ERROR: Transaction already closed!
""")
print("\nWhy this fails:")
print("1. execute_write() runs the lambda function within a managed transaction")
print("2. When the lambda returns, the transaction is committed/closed")
print("3. Trying to access result.values() after this fails")
async def demonstrate_solution():
"""Show the correct pattern that avoids transaction scope errors"""
print("\n=== CORRECT PATTERN ===")
print("""
# Solution: Process results within the transaction scope
async def execute_query(tx):
result = await tx.run(query, params)
# Process the results INSIDE the transaction
records = await result.data() # or result.values()
# Return the processed data
if records and len(records) > 0:
return records[0].get("fieldName", default_value)
return default_value
# execute_write returns what the function returns
processed_result = await session.execute_write(execute_query)
""")
print("\nWhy this works:")
print("1. The async function processes results within the transaction")
print("2. It returns the processed data, not the result object")
print("3. execute_write() returns this processed data after closing the transaction")
async def main():
print("Neo4j Transaction Scope Diagnostic")
print("==================================\n")
await demonstrate_problem()
await demonstrate_solution()
print("\n=== FILES FIXED ===")
print("1. knowledge_graph_incarnation.py - delete_entities method")
print("2. server.py - get_guidance_hub method")
print("\nBoth now use the correct pattern to process results within transaction scope.")
if __name__ == "__main__":
asyncio.run(main())
