Add ActiveHash::Relation#or to support OR-like queries

[opsys-saito]

Summary

This PR adds support for ActiveHash::Relation#or, allowing OR-like queries similar to ActiveRecord:

Model.where(condition_a).or(Model.where(condition_b))

The implementation returns a new relation representing the union of both result sets, deduplicated by id.

Behavior

• Supports chaining:

  Model.where(a: 1).or(Model.where(a: 2)).where(b: 3)

• Deduplicates records based on id
• Raises an ArgumentError when combining relations from different models

Implementation Notes

Since ActiveHash operates entirely in memory, this implementation performs a union of the evaluated result sets rather than merging condition trees.

The returned value remains an ActiveHash::Relation, preserving chainability and compatibility with existing APIs.

Tests

Added specs covering:

• Union of two relations
• Deduplication behavior
• Chainability after or
• Error handling for mismatched models

[kbrock]

This looks sweet.

Could you add a or() with anoother operator, like an order?

[opsys-saito]

Thanks! That's a great point 👍

Just to clarify — would it make sense to support or for relations with additional operators like order only when those operators are identical?

In that case, we could raise an error when they differ, similar to ActiveRecord’s behavior for incompatible relations.

Happy to adjust depending on your preference!

[kbrock]

@opsys-saito sorry. I was not clear

Please just add a test with an order.

Something like?

Hoping Model.where(:id => 1).or(Model.where(:id => [2, 3])).order(:id => :desc)

Maybe using country - just throw an order in there ensure it works, and call it a day.

[opsys-saito]

@kbrock

Thanks for the clarification!

I've added a test to ensure or works correctly when combined with order. Let me know if anything else should be covered.

[kbrock]

This looks great. thanks

Just waiting for Green then I'll merge

[opsys-saito]

@kbrock
Thanks for merging this! Really looking forward to the release 🚀