Event Schema Version Migration Tool

WHAT IT DOES

The Event Schema Version Migration Tool is a developer tool that analyzes and documents changes in event schemas between contract versions. It compares event definitions from old and new contract versions, detecting modifications in event signatures, parameter lists, and parameter types. The tool generates a comprehensive migration report that identifies unchanged events, modified events (with before/after parameter comparisons), removed events, and added events. This helps developers understand the impact of event schema changes and plan data migration strategies.

HOW TO USE

Enter your old event definitions in the first text area (one per line, format: Name(type1,type2,...)) and your new event definitions in the second text area. Click "generate migration report" to compare the definitions. The tool displays a detailed report showing unchanged events, modified events with parameter differences, removed events, and added events. The report includes a summary of the changes and recommendations for migrating event listeners and indexers. The tool is designed for manual review and documentation purposes.

TECHNICAL MECHANISM

The tool parses event definitions from user input using regex to extract event names and parameter types. Each definition is validated against the format "Name(type1,type2,...)" with support for empty parameter lists. The comparison engine builds maps of events by name for both old and new versions. It then iterates through all events, categorizing them into four groups: unchanged (same name and parameter signature), modified (same name but different parameter list), removed (present only in old), and added (present only in new). For modified events, the tool records both the old and new parameter lists for side-by-side comparison. The report is presented with color-coded sections and a summary assessment, including recommendations for handling each type of change.

WHAT IT CANNOT SEE

The tool cannot automatically transform or migrate existing event data. It cannot detect semantic changes in event meaning without additional context. The tool cannot determine if new event fields can be derived from old data. It cannot handle events that are renamed or removed entirely. The tool cannot account for events that are emitted conditionally based on runtime state. It cannot validate that the migration will work for all historical events without full data analysis. The tool cannot generate code for transforming event data without manual specification.

PLEASE NOTE

This tool is designed for Ethereum Virtual Machine (EVM) compatible chains but works with any event definition format. The tool performs static comparison of event signatures and does not analyze the actual data structures beyond parameter types. The generated report provides a starting point for migration planning but does not replace manual review of event data. For events with changed parameters, users must determine how to map old data to the new schema. The tool is intended for development and documentation purposes, not for automated data migration.