fix(idempotency): serialize Pydantic models with mode='json' for UUID/date support

[abhu85]

Issue number: closes #8065

Summary

Changes

The _prepare_data() function in aws_lambda_powertools/utilities/idempotency/base.py was calling model_dump() without specifying mode="json", which defaults to mode="python". This caused Pydantic models containing UUIDs, dates, or datetimes to fail with "Object of type UUID is not JSON serializable" error when used with @idempotent_function.

Fix: Changed data.model_dump() to data.model_dump(mode="json") to ensure proper JSON serialization of UUID, date, and datetime fields.

User experience

Before:

from uuid import UUID
from pydantic import BaseModel

class PaymentInput(BaseModel):
    payment_id: UUID
    customer_id: str

@idempotent_function(data_keyword_argument="payment", persistence_store=persistence_layer)
def process_payment(payment: PaymentInput):
    return {"status": "processed"}

# Raises: Object of type UUID is not JSON serializable

After:

# Same code now works correctly - UUID is serialized as string for idempotency key generation
process_payment(payment=PaymentInput(payment_id=uuid4(), customer_id="123"))
# Returns: {"status": "processed"}

---

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[leandrodamascena]

Hey @abhu85, great fix!
At glance I thought it could be a breaking change, but after inspecting the code I saw that Pydantic models with complex types (UUID, date, datetime, Decimal, Path) would already crash during JSON hashing before this fix. For models using only primitive types (str, int, float, bool), both modes produce identical output, so existing users aren't affected. Thats really nice.

I made a few changes on top of your PR:

• Renamed test file to test_idempotency_pydantic_json_serialization.py to better reflect its scope
• Removed _prepare_data unit tests - functional tests should go through @idempotent_function
• Added integration tests for date, datetime, Decimal, and PurePosixPath (original only covered UUID) - All tests follow the existing pattern in test_idempotency_with_pydantic.py

Thanks a lot, approved!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.64%. Comparing base (b716437) to head (8264fb1).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8075   +/-   ##
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  Coverage    96.64%   96.64%           
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  Files          282      282           
  Lines        13791    13791           
  Branches      1102     1102           
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  Hits         13329    13329           
  Misses         339      339           
  Partials       123      123           

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[boring-cyborg]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!