examples

RowQuery Examples

This directory contains runnable examples demonstrating RowQuery features.

Running Examples

All examples use SQLite with in-memory or temporary databases, so no external database setup is required.

# Run an example
python examples/01_basic_query.py

Examples Overview

01_basic_query.py

Basic query execution using Engine and SQLRegistry. Shows:

• Creating a connection
• Loading SQL files
• fetch_one(), fetch_all(), fetch_scalar() methods

02_model_mapping.py

Mapping query results to Python objects. Shows:

• Dataclass mapping
• Pydantic model mapping
• Using ModelMapper

03_aggregate.py

Complex object graph reconstruction from joined queries. Shows:

• Aggregate mapping with collections
• Single-pass O(n) reconstruction
• The aggregate() DSL

04_transactions.py

Transaction management. Shows:

• Context manager usage
• Automatic rollback on error
• Manual commit/rollback

05_async.py

Async/await support. Shows:

• AsyncEngine usage
• Async query execution
• Async transactions

06_migrations.py

Database migration management. Shows:

• MigrationManager usage
• Version tracking
• Migration application

07_repository.py

Repository pattern for DDD. Shows:

• Using Repository base class
• Entity persistence
• Query encapsulation

Adapting Examples

These examples use SQLite for simplicity. To use with other databases:

# PostgreSQL
config = ConnectionConfig(
    driver="postgresql",
    host="localhost",
    port=5432,
    database="mydb",
    user="user",
    password="pass"
)

# MySQL
config = ConnectionConfig(
    driver="mysql",
    host="localhost",
    port=3306,
    database="mydb",
    user="user",
    password="pass"
)

# Oracle
config = ConnectionConfig(
    driver="oracle",
    host="localhost",
    port=1521,
    service_name="ORCLPDB1",
    user="user",
    password="pass"
)