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AI Prompts Library

This page provides optimized prompts for common development tasks when using AI assistants with the MBC CQRS Serverless framework.

Module Generation​

Create a New CQRS Module​

Create a new CQRS module for [FEATURE_NAME] in MBC CQRS Serverless with:
- CommandModule registration with table name "[TABLE_NAME]"
- Command handlers: Create, Update, Delete (async processing)
- DataService for queries: list with pagination, getById
- Entity extending DataEntity with attributes
- DTOs for create, update, and response
- Follow existing patterns in the codebase

Create a Module with RDS Sync​

Create a CQRS module for [FEATURE_NAME] that syncs data to RDS:
- CommandModule with DataSyncHandler for RDS
- TypeORM entity for the RDS table
- Prisma schema if using Prisma
- Handle create, update, and delete sync operations
- Include error handling for sync failures

Command Operations​

Implement Async Command​

Implement an async command handler for [OPERATION] in MBC CQRS Serverless:
- Use publishAsync for immediate response
- Include input validation in DTO
- Set appropriate command source
- Handle optimistic locking with version
- Follow the existing command pattern in this codebase

Implement Sync Command​

Implement a synchronous command for [OPERATION] that waits for completion:
- Use publishSync method
- Return the fully processed result
- Include proper error handling
- Consider timeout implications

Query Operations​

List Query with Filters​

Implement a list query for [ENTITY] with:
- Pagination support (limit, cursor)
- Filter by [FIELD_NAMES]
- Sort options
- Use DataService.listItems with skExpression
- Return paginated response with items and cursor

Detail Query​

Implement a detail query to get [ENTITY] by ID:
- Use DataService.getItem
- Handle VERSION_LATEST for latest version
- Include proper error handling for not found
- Serialize response for API output

Event Handling​

Create Custom Event Handler​

Create a custom event handler for [EVENT_TYPE] in MBC CQRS Serverless:
- Extend appropriate event class (DynamoDbEvent, SqsEvent, etc.)
- Implement IEventHandler interface
- Register handler in EventHandlerModule
- Include error handling and logging
- Follow the event handling patterns in the codebase

DynamoDB Stream Handler​

Create a DynamoDB stream handler to [PURPOSE]:
- Process INSERT, MODIFY, REMOVE events
- Filter by table name if needed
- Extract old and new images
- Implement idempotent processing
- Handle errors appropriately

Data Sync​

Create Data Sync Handler​

Create a DataSyncHandler to sync [ENTITY] to [TARGET]:
- Implement IDataSyncHandler interface
- Handle up() for create/update operations
- Handle down() for delete operations
- Use transactions where appropriate
- Include error handling and rollback logic

Multi-Tenancy​

Implement Tenant-Aware Feature​

Implement [FEATURE] with multi-tenancy support:
- Extract tenantCode from invocation context
- Use tenant-prefixed partition keys
- Apply tenant isolation in queries
- Include tenant validation
- Follow existing tenant patterns in the codebase

Testing​

Unit Test for Command Handler​

Write unit tests for [COMMAND_HANDLER]:
- Mock CommandService and dependencies
- Test successful command execution
- Test validation errors
- Test version conflict handling
- Use Jest with AWS SDK mocks

Integration Test​

Write integration tests for [FEATURE]:
- Set up test DynamoDB tables
- Test full command-query flow
- Verify data sync if applicable
- Clean up test data after each test
- Use LocalStack for local testing

Debugging​

Diagnose Version Conflict​

I'm getting a "version not match" error when updating [ENTITY].
Please help me:
1. Understand why this error occurs in CQRS/Event Sourcing
2. Check if I'm using the correct version in my update
3. Suggest how to handle concurrent updates properly
4. Show me how to implement retry logic if needed

Diagnose Data Sync Issues​

Data is not syncing to RDS for [ENTITY]. Please help me:
1. Check if DataSyncHandler is properly registered
2. Verify the sync handler implementation
3. Check for errors in the sync process
4. Suggest debugging steps and logging

Diagnose Event Processing​

Events are not being processed for [EVENT_TYPE]. Please check:
1. Event handler registration in the module
2. Event class implementation
3. SQS/SNS configuration
4. Error handling and dead letter queue setup

Architecture Review​

Review Module Implementation​

Review this [MODULE_NAME] module implementation for:
- Proper CQRS pattern adherence (command/query separation)
- Event sourcing best practices
- Multi-tenancy implementation
- Error handling completeness
- Performance considerations
- Security best practices

Review for Production Readiness​

Review [FEATURE] for production readiness:
- Error handling and recovery
- Logging and monitoring
- Performance under load
- Security vulnerabilities
- Data consistency guarantees
- Rollback procedures

Migration​

Create Migration for Schema Change​

Create a migration for [SCHEMA_CHANGE]:
- TypeORM migration file
- Handle existing data transformation
- Include rollback procedure
- Test with sample data
- Document breaking changes if any

Best Practices​

When using these prompts:

  1. Be Specific: Replace placeholders with actual names and requirements
  2. Provide Context: Include relevant code snippets or file paths
  3. Reference Existing Code: Point to similar implementations in your codebase
  4. Specify Constraints: Mention any performance, security, or compatibility requirements
  5. Request Explanations: Ask AI to explain its implementation choices

See Also​