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Allow params in fact and event to be an array of Record<K,T>#422

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aprakhar:feat-params-be-array-of-records
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Allow params in fact and event to be an array of Record<K,T>#422
aprakhar wants to merge 1 commit intoCacheControl:masterfrom
aprakhar:feat-params-be-array-of-records

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@aprakhar
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@aprakhar aprakhar commented Aug 4, 2025

The params property in fact and event, support an array of Record<Keys, Type>.
I've updated the Typescript type of params. I've moved the type into TParams, which replaces Record<string, any>

@aprakhar aprakhar marked this pull request as ready for review August 4, 2025 06:40
@chris-pardy
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Thanks for the PR @aprakhar!

I think this change as-is would be a breaking change at the type level. Specifically, DynamicFactCallback changes its params parameter from Record<string, any> to Record<string, any> | Record<string, any>[]. That means anyone implementing a dynamic fact callback today would get a type error — their existing (params: Record<string, any>, almanac) => ... signatures would no longer satisfy the widened union without narrowing it first.

Similarly, consumers reading ConditionProperties.params from rule results who have typed their code assuming it's always a record would also break.

Widening input types (like ConditionProperties.params when constructing rules) is fine, but widening callback parameters and output types is a breaking change since it forces consumers to handle a new case.

One option would be to scope this to just the input positions (e.g. where users are defining conditions/events) while keeping the callback and result types unchanged. Alternatively this could be something we pick up in the next major version.

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