Features

Advanced Features

This chapter covers the advanced features of RhoSocial ActiveRecord that help you build robust and reliable database applications.

Overview

RhoSocial ActiveRecord provides several advanced features for handling complex database operations:

1. Transaction Management

   • ACID compliance

   • Nested transactions

   • Savepoints

   • Isolation levels

   • Transaction callbacks

2. Error Handling

   • Exception hierarchy

   • Database-specific errors

   • Recovery strategies

   • Error logging

   • Retry mechanisms

Transaction Support

Transactions ensure data consistency across multiple operations. Example use cases:

Social Media Application

# Create post with tags
with Post.transaction():
    # Create post
    post = Post(user_id=1, content="Hello world")
    post.save()
    
    # Add tags
    for tag_name in ["tech", "python", "web"]:
        tag = Tag.find_or_create(name=tag_name)
        PostTag(post_id=post.id, tag_id=tag.id).save()

E-commerce System

# Process order
with Order.transaction():
    # Create order
    order = Order(user_id=1, total=Decimal('0'))
    order.save()
    
    # Add items and update stock
    for item in cart_items:
        product = Product.find_one_or_fail(item.product_id)
        
        # Check stock
        if product.stock < item.quantity:
            raise ValueError("Insufficient stock")
        
        # Update stock
        product.stock -= item.quantity
        product.save()
        
        # Create order item
        OrderItem(
            order_id=order.id,
            product_id=product.id,
            quantity=item.quantity,
            price=product.price
        ).save()

Error Handling

RhoSocial ActiveRecord provides comprehensive error handling:

from rhosocial.activerecord.backend import (
    DatabaseError,
    ConnectionError,
    TransactionError,
    RecordNotFound,
    ValidationError
)

try:
    with Order.transaction():
        order.process()
except ConnectionError:
    # Handle connection issues
    reconnect_and_retry()
except ValidationError as e:
    # Handle validation errors
    log_validation_error(e)
except TransactionError as e:
    # Handle transaction failures
    notify_admin(e)
except DatabaseError as e:
    # Handle other database errors
    log_error(e)

In This Chapter

1. Transactions

   • Learn about transaction management

   • Understand isolation levels

   • Use nested transactions

   • Handle transaction errors

2. Error Handling

   • Understand error types

   • Implement error handling strategies

   • Use recovery mechanisms

   • Log and monitor errors

Best Practices

1. Always Use Transactions for multi-step operations

2. Implement Proper Error Handling for all database operations

3. Log Errors for monitoring and debugging

4. Plan Recovery Strategies for different error scenarios

5. Test Error Cases thoroughly

Next Steps

1. Read Transactions for detailed transaction management

2. Study Error Handling for comprehensive error handling

3. Explore Backend Documentation for backend-specific features