fix(sdk-python): avoid empty JSON body on GET

[mahendrarathore1742]

This PR fixes an issue where the SDK would send an empty JSON body ({}) with GET requests, which violates HTTP specs and is rejected by some load balancers (e.g., Google Cloud). Now, if no additional body parameters are provided, the request body is set to None for GET requests.

Fix: Avoid sending {} as the body for GET requests.
Adds unit tests to ensure correct request body behavior.

Disclaimer: Experimental PR review

Greptile Summary

This PR fixes a bug where GET requests could send an empty JSON body ({}) that is rejected by some load balancers (e.g., Google Cloud). The fix refactors maybe_filter_request_body to return None directly when no additional_body_parameters are present, rather than returning {} and relying on a downstream json_body != {} guard in get_request_body to convert it to None.

Key changes:

• maybe_filter_request_body now short-circuits to None when request_options is None or when additional_body_parameters is absent/empty, making the intent explicit.
• The downstream != {} safety check in get_request_body (lines 204–206) is retained and still useful for the non-None data mapping path, which is unchanged.
• Three unit tests are added covering the main scenarios; a test for request_options=None would complete coverage of the new early-return path.

Confidence Score: 5/5

• Safe to merge; the fix is correct and functionally equivalent while being cleaner, with only a minor test-coverage gap.
• All remaining feedback is P2 (missing a single unit-test case for request_options=None). The core logic change is sound: maybe_filter_request_body previously returned {} for the no-body case which was already neutralised by the != {} check downstream, and the new code simply makes that None return explicit. No regressions are introduced.
• No files require special attention beyond the minor test-coverage suggestion in tests/test_http_client.py.

Important Files Changed

Filename	Overview
langfuse/api/core/http_client.py	Refactored maybe_filter_request_body to return None directly when additional_body_parameters is absent/empty, replacing the indirect {} → None conversion that relied on a downstream != {} check in get_request_body. Logic is correct and cleaner.
tests/test_http_client.py	New test file with three cases covering the fix; missing a request_options=None test for completeness, but all existing assertions are correct.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[get_request_body called] --> B{data is not None?}
    B -- Yes --> C[maybe_filter_request_body\nwith data]
    B -- No --> D[maybe_filter_request_body\nwith json]

    D --> E{request_options\nis None?}
    E -- Yes --> F[return None\nNEW short-circuit]
    E -- No --> G{additional_body_parameters\nfalsy or missing?}
    G -- Yes --> H[return None\nNEW short-circuit]
    G -- No --> I[return jsonable_encoder\nof params]

    C --> J[data_content merged dict]

    I --> K[json_body set]
    F --> K
    H --> K
    J --> L[data_body set]

    K --> M{json_body is empty dict?}
    M -- Yes --> N[return None\nsafety net]
    M -- No --> O[return json_body]
    L --> P{data_body is empty dict?}
    P -- Yes --> Q[return None\nsafety net]
    P -- No --> R[return data_body]

    style F fill:#90EE90
    style H fill:#90EE90

Loading

_{Reviews (1): Last reviewed commit: "fix(sdk-python): avoid empty JSON body o..." | Re-trigger Greptile}

_{(2/5) Greptile learns from your feedback when you react with thumbs up/down!}

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[CLAassistant]

All committers have signed the CLA.

[hassiebp]

Thanks for raising this! This should've been already fixed on main. Could you please share a small repro example for your case?

[mahendrarathore1742]

Hi @hassiebp! Here's the repro context you asked for.

This issue was also independently reported in the main langfuse repo: langfuse/langfuse#12939

Root cause (confirmed):
When request_options is passed but data is None (as is the case for all GET requests), maybe_filter_request_body returns {} instead of None. That empty dict then gets passed as the JSON body of the GET request, which violates HTTP semantics and is rejected by load balancers.

Minimal repro:

from langfuse import Langfuse

langfuse = Langfuse(
    public_key="pk-...",
    secret_key="sk-...",
    host="https://your-self-hosted-endpoint"
)

# Passing request_options to any GET endpoint triggers the bug
trace = langfuse.api.trace.get(
    trace_id, request_options={"timeout_in_seconds": 30}
)

Affected version: Python SDK 1.38.0, Langfuse 3.147.0 (self-hosted)

Observed error: Google Cloud load balancer rejects the request due to a GET request carrying a body ({}). The same issue has also been reported causing 403s from CloudFront.

Could you clarify which commit on main you believe already fixed this? The linked file at e32aeb2 still shows the original code. If it has been fixed in a more recent commit, I'm happy to close this PR — just want to confirm the fix is actually shipped.