Improve Handling of Empty Queries

[kenara]

Summary

This PR addresses the issue of empty queries in the ZCatalog returning no results without explicit feedback. It proposes raising a ValueError when an empty query is detected, providing clear feedback to developers.

Background

In the current implementation of ZCatalog in Zope 4 and 5, an empty query returns no results without any indication to the user. This behavior can be confusing and complicates debugging.

Justification

• Improved User Experience: Providing explicit feedback helps users understand why no results are returned, reducing confusion and aiding in debugging.
• Consistency with Modern Systems: Other indexing systems like Elasticsearch and Solr handle empty queries transparently, either by returning all documents or providing clear feedback.
• Error Prevention: Encouraging explicit query parameters reduces the risk of unintentional empty queries, which can improve the reliability of applications using ZCatalog.

Changes

• Add a check in the searchResults method to raise a ValueError when an empty query is detected.
• Log a warning when an empty query is processed.
• Update documentation to reflect this new behavior, providing guidance on how to handle empty queries.

Benefits

• Improved Developer Experience: Clear feedback helps developers understand and debug their queries more effectively.
• Alignment with Modern Practices: Makes ZCatalog's behavior consistent with other widely-used indexing systems.
• Error Prevention: Reduces the risk of unintentional empty queries, improving application reliability.

Impact

• Developers: Clearer understanding of query failures, leading to faster debugging and development cycles.
• Performance: Minimal impact as the change involves simple conditional checks and logging.
• Compatibility: Maintains backward compatibility by raising errors only when queries are genuinely empty.

[d-maurer]

kenara wrote at 2024-5-25 07:39 -0700:

This PR addresses the issue of empty queries in the ZCatalog returning no results without explicit feedback. It proposes raising a ValueError when an empty query is detected, providing clear feedback to developers.

The catalog usually returns the intersection of the subquery results. As a consequence, an empty query should return all possible results (as ZCatalog did in its early days).