feat: dependent required tag

[victoraugustolls]

This pull request adds the ability to define some fields to be required only when other fields are present with the struct tag dependentRequired.

Resolves issue #296

[victoraugustolls]

@danielgtaylor do you think we should write a how-to docs for conditional-fields?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.11%. Comparing base (41e6941) to head (5b2b9c3).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #303      +/-   ##
==========================================
+ Coverage   95.08%   95.11%   +0.03%     
==========================================
  Files          19       19              
  Lines        2744     2765      +21     
==========================================
+ Hits         2609     2630      +21     
  Misses         98       98              
  Partials       37       37              

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[victoraugustolls]

@danielgtaylor While making this pull request, there was a schema.Required and schema.requiredMap, so I followed the same approach for the dependentRequired. But we could get away only with the DependentRequired if that is okay with you. I will push the changes. Let me know if you'd like me to revert them.

One thing to notice: I did not validate if the dependents fields exist, but I could add this validation and panic, as it seems there is no way to return an error. Since this would panic when creating the schema, it wouldn't impact a running app. Let me know your thoughts on this.

[danielgtaylor]

LGTM, great work! Thank you 👍

I think it would be good to panic if there is a typo or the wrong field name is provided, so I'll hold off merging unless you want to do that in another PR.

[danielgtaylor]

Oh, and one last thing, you'll want to modify https://github.com/danielgtaylor/huma/blob/main/docs/mkdocs.yml#L54-L59 so your new how-to doc shows up in the menu properly!

[victoraugustolls]

@danielgtaylor done! added the panic for non existing fields and updated the docs!