fix(recharts): support function vars for axis tick formatters

[harsh21234i]

Summary

• Allow Reflex function vars as Recharts axis tick formatters.
• Reject dynamic string vars with guidance to use FunctionStringVar.
• Add regression tests and a changelog entry.

Testing

• Recharts cartesian unit tests: 18 passed.
• scripts/make_pyi.py --check passed.
• Ruff focused checks and git diff --check passed.

Fixes #7257

[cubic-dev-ai]

All reported issues were addressed across 4 files

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<sub>Reply with feedback, questions, or to request a fix.

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[greptile-apps]

Confidence Score: 5/5

[Medium risk] Adds function variable support to chart axis tick formatters.

The PR appears safe to merge; the previously reported regression-test mismatch is fixed and no new issue was identified.

Summary

This PR allows Recharts axis tick formatters to accept Reflex function vars while rejecting dynamic string vars with guidance. It also adds regression tests and a changelog fragment.

_{Reviews (7) · Last reviewed commit: "update test assertion for new exception ..."}

[codspeed]

Merging this PR will not alter performance

✅ 147 untouched benchmarks
⏩ 17 skipped benchmarks¹

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_{Comparing harsh21234i:fix/7257-recharts-function-tick-formatter (38cff9c) with main (7b90fd3)}

Footnotes

1. 17 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[masenf]

Thanks for the fix

[cubic-dev-ai]

All reported issues were addressed across 2 files (changes from recent commits).

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

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[FarhanAliRaza]

Please remove this branch. It rejects a plain rx.Var with type Any, and that input works on main.

XAxis.create(tick_formatter=rx.Var("((v) => v)")) renders tickFormatter:((v) => v) on main. On this branch it raises TypeError: tick_formatter must be a FunctionVar. A user can use rx.Var("myFormatter") to point at a JS function from custom code, so this breaks working apps. Please also add a test for this case.

[masenf]

idk about this suggestion. a Var could be anything, we don't want to take anything for this prop. The point of strong type hinting is that it makes it harder to represent a bad state. So while a subset of plain Var might work, there's a lot of Var objects that won't work and will give weird frontend errors as runtime.

I think it makes sense to enforce that this field is a plain literal string, or explicitly a FunctionVar

[FarhanAliRaza]

Please remove the FunctionVar branch and the callable branch. The framework already does both of these checks.

• The FunctionVar branch puts back the value that is already in props. The new annotation accepts FunctionVar, so super().create() lets it through.
• super().create() already raises TypeError for a Python lambda on main.

With only the str-Var check kept, FunctionStringVar, .partial(), ArgsFunctionOperation, a literal string and an Any Var all render correctly. A State str var is still rejected. _TICK_FORMATTER_CALLABLE_ERROR and _TICK_FORMATTER_TYPE_ERROR are then unused and can go too.

[FarhanAliRaza]

create() now raises TypeError here. Please add a Raises: section to the Axis.create docstring. The summary line talks only about string formatters, so please update it to describe function vars too.

[FarhanAliRaza]

Please move these tests into tests/units/components/recharts/test_cartesian.py. That file already has the tick_formatter tests, including the tests that reject non-callables and Python callables.

[FarhanAliRaza]

I tested this branch in a small Reflex app with four line charts. Each chart uses a different tick_formatter: a literal string, a FunctionStringVar, a FunctionStringVar.partial(State.suffix), and an ArgsFunctionOperation.

All four charts render the formatted ticks. A click that changes State.suffix updates the partial formatter's ticks. The browser console shows no errors.

I also called XAxis.create() with the same inputs on main and on this branch. On main, a FunctionStringVar raises the TypeError from #7257, and this branch fixes that. A State str var is now rejected, as the issue asks. A plain rx.Var with type Any works on main but raises on this branch.

The requested changes are in the inline comments.