Summary

This PR introduces support for optional decimal rounding in theDecimalField serializer field. By adding arounding parameter, developers can now control how decimal values are quantized during serialization — such as rounding up, down, or to the nearest value.

Motivation

Controlling decimal precision is crucial in real-world APIs that handle:

• 💸 Financial calculations (e.g., prices, taxes, discounts)
• 📏 Measurement tools (e.g., distances, weights)
• 📊 Scientific data and reports

WhileDecimalField enforces digit and decimal precision, it lacked direct control over therounding mode. This enhancement improves the flexibility and precision of API responses for such use cases.

What's Changed

• 🔧 Added a newrounding parameter toDecimalField.__init__()
• 🧮 Applied rounding logic into_representation() using Python'sDecimal.quantize()
• 🔒 Added validation to ensurerounding is one of thedecimal.ROUND_* constants
• ✅ Added a dedicated unit test intests/test_fields.py to verify rounding behavior (e.g.,ROUND_HALF_UP)

Example Usage

fromdecimalimportROUND_HALF_UPprice=serializers.DecimalField(max_digits=6,decimal_places=2,rounding=ROUND_HALF_UP)---## Backward Compatibility✅Thenewparameteris**optional**  ✅If`rounding`isnotprovided,existingbehaviorisunchanged  ✅Fullybackward-compatiblewithallexistingserializers---## Testing-AllcoreDRFtestspassusing`pytest`-Customtestaddedforroundingbehaviorin`tests/test_fields.py`---## Additional Notes-ContributionalignswithDRF’sgoalofbeingaflexible,production-gradeAPItoolkit-Thisfeaturehasreal-worlddemandacrossfinance,commerce,andanalytics---Pleaseletmeknowifanychangesorenhancementsareneeded!