fix(models): avoid AttributeError on LiteLLM_ProxyModelTable revalidation

[wuying8]

TLDR

Problem this solves:

• POST /model/block and POST /model/unblock fail with HTTP 500 AttributeError during Pydantic response validation

How it solves it:

• Return non-dict inputs unchanged in LiteLLM_ProxyModelTable.check_potential_json_str before accessing dict keys

Relevant issues

Linear ticket

Pre-Submission checklist

• I have added meaningful tests
• My PR passes all CI/CD checks
• My PR's scope is as isolated as possible

Proof of Fix

Before fix:
POST /model/block -> HTTP 500 (AttributeError: 'LiteLLM_ProxyModelTable' object has no attribute 'get')

After fix:
POST /model/block -> HTTP 200 OK with model details payload

Type

🐛 Bug Fix

Changes

• litellm/models/model.py: Type-guard values in check_potential_json_str validator to handle LiteLLM_ProxyModelTable instances during response revalidation.
• tests/test_litellm/models/test_models.py: Add regression test for model_validate on an existing LiteLLM_ProxyModelTable instance.

Final Attestation

• The tests check the right things, including the edge cases, and regressions in the respective real-world customer use-cases are not possible after this PR

[CLAassistant]

All committers have signed the CLA.

[greptile-apps]

Greptile Summary

The PR prevents LiteLLM_ProxyModelTable revalidation from treating an existing model instance as a dictionary.

• Adds a type guard before dictionary-specific JSON-field normalization.
• Adds a regression test covering model_validate with an existing model instance.

Confidence Score: 5/5

The PR appears safe to merge, with no actionable regressions identified.

The validator now safely preserves non-dictionary inputs while retaining the existing parsing behavior for dictionary construction paths, and the regression test covers the reported model-instance revalidation case.

Important Files Changed

Filename	Overview
litellm/models/model.py	Adds a narrow input-shape guard while preserving JSON-string normalization for dictionary inputs.
tests/test_litellm/models/test_models.py	Adds focused regression coverage confirming that an existing proxy model instance can be revalidated without losing field values.

_{Reviews (1): Last reviewed commit: "fix(models): avoid AttributeError on Lit..." | Re-trigger Greptile}

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
litellm/models/model.py	50.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[codspeed-hq]

Merging this PR will not alter performance

✅ 31 untouched benchmarks

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_{Comparing wuying8:litellm_fix_model_block_response_serialization (f343c3f) with litellm_internal_staging (ff02d5c)}