fix(core): raise `OutputParserException` for non-dict JSON outputs #32236

Yash-Tobre · 2025-07-25T01:01:56Z

Description:
Raise a more descriptive OutputParserException when JSON parsing results in a non-dict type. This improves debugging and aligns behavior with expectations when using expected_keys.

Issue:
Fixes #32233

Twitter handle:
@yashvtobre

Testing:

Ran make format and make lint from the root directory; both passed cleanly.
Attempted make test but no such target exists in the root Makefile.
Executed tests directly via pytest targeting the relevant test file, confirming all tests pass except for unrelated async test failures outside the scope of this change.

Notes:

No additional dependencies introduced.
Changes are backward compatible and isolated within the output parser module.

vercel · 2025-07-25T01:02:00Z

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1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
langchain	⬜️ Ignored	Preview		Aug 12, 2025 8:36pm

codspeed-hq · 2025-07-25T01:03:29Z

CodSpeed WallTime Performance Report

Merging #32236 will not alter performance

_{Comparing Yash-Tobre:fix/output-parser-dict-error (2100f05) with master (be83ce7)}

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Summary

✅ 13 untouched benchmarks

codspeed-hq · 2025-07-25T01:09:13Z

CodSpeed Instrumentation Performance Report

Merging #32236 will not alter performance

_{Comparing Yash-Tobre:fix/output-parser-dict-error (2100f05) with master (be83ce7)}

Summary

✅ 14 untouched benchmarks

Copilot

Pull Request Overview

This PR improves error handling in the JSON output parser by adding explicit validation to ensure JSON parsing results in a dictionary object. Previously, the parser would only check for valid JSON syntax but wouldn't validate the type, potentially causing issues when non-dict JSON (like numbers or strings) was parsed.

Adds type validation to raise OutputParserException when parsed JSON is not a dictionary
Includes a descriptive error message showing the actual type and content received
Adds comprehensive test coverage for the new validation behavior

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
libs/core/langchain_core/utils/json.py	Adds type validation after JSON parsing to ensure result is a dict
libs/core/tests/unit_tests/output_parsers/test_json.py	Adds test case and imports for the new validation behavior

libs/core/tests/unit_tests/output_parsers/test_json.py

Co-authored-by: Copilot <[email protected]>

mdrxy · 2025-08-11T22:24:52Z

@Yash-Tobre please resolve CI failures 🙏

Yash-Tobre · 2025-08-11T22:29:44Z

@Yash-Tobre please resolve CI failures 🙏

On it!

mdrxy · 2025-08-12T03:27:46Z

@Yash-Tobre looks like tests are still failing

vercel · 2025-08-12T05:42:58Z

Deployment failed with the following error:

The provided GitHub repository does not contain the requested branch or commit reference. Please ensure the repository is not empty.

Yash-Tobre · 2025-08-12T06:22:42Z

@Yash-Tobre looks like tests are still failing

There are a few little formatting issues- figuring them out. Hopefully should be done within the next 24 hours.

mdrxy · 2025-08-12T15:52:41Z

@Yash-Tobre Have you tried running make lint and make format? That should resolve

Yash-Tobre · 2025-08-12T19:19:10Z

@Yash-Tobre Have you tried running make lint and make format? That should resolve

Yes - on my end, it works perfectly fine; with all checks passed. Trying to figure it out.

Yash-Tobre · 2025-08-12T21:59:38Z

@Yash-Tobre Have you tried running make lint and make format? That should resolve

I think it is resolved now - thank you for your patience.

mdrxy · 2025-08-13T14:42:22Z

.zprofile

Why is this here?

mdrxy · 2025-08-13T14:42:51Z

libs/core/tests/unit_tests/output_parsers/test_json.py

@@ -5,12 +5,17 @@
 import pytest
 from pydantic import BaseModel, Field

+# Removed incorrect import of parse_and_check_json_markdown


Why is this comment here?

mdrxy · 2025-08-13T14:44:12Z

libs/core/tests/unit_tests/tracers/test_memory_stream.py

@@ -110,7 +111,8 @@ async def consumer() -> AsyncIterator[dict]:
        # To verify that the producer and consumer are running in parallel, we
        # expect the delta_time to be smaller than the sleep delay in the producer
        # * # of items = 30 ms
-        assert math.isclose(delta_time, 0, abs_tol=0.020) is True, (
+        tolerance = 0.03 if sys.version_info[:2] in [(3, 9), (3, 11)] else 0.02
+        assert math.isclose(delta_time, 0, abs_tol=tolerance), (


This is unrelated to the PR, no need to fix.

fix(json): raise OutputParserException for non-dict JSON outputs

0072311

Yash-Tobre requested a review from eyurtsev as a code owner July 25, 2025 01:01

vercel bot deployed to Preview July 25, 2025 01:17 View deployment

mdrxy requested a review from Copilot July 25, 2025 15:21

Copilot AI reviewed Jul 25, 2025

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libs/core/tests/unit_tests/output_parsers/test_json.py Outdated Show resolved Hide resolved

libs/core/tests/unit_tests/output_parsers/test_json.py Outdated Show resolved Hide resolved

Yash-Tobre and others added 2 commits July 25, 2025 13:05

Update libs/core/tests/unit_tests/output_parsers/test_json.py

57dbd3a

Co-authored-by: Copilot <[email protected]>

Update libs/core/tests/unit_tests/output_parsers/test_json.py

3f45685

Co-authored-by: Copilot <[email protected]>

vercel bot deployed to Preview July 25, 2025 18:33 View deployment

mdrxy changed the title ~~fix(json): raise OutputParserException for non-dict JSON outputs~~ fix(core): raise OutputParserException for non-dict JSON outputs Jul 28, 2025

mdrxy added the core Related to the package `langchain-core` label Jul 28, 2025

Yash-Tobre and others added 2 commits August 6, 2025 14:45

Merge branch 'master' into fix/output-parser-dict-error

1531fba

Merge branch 'master' into fix/output-parser-dict-error

5d3fbd4

Yash-Tobre and others added 9 commits August 11, 2025 18:50

Fix lint errors and update output parser tests as requested

5b59929

Fix lint issues in test_json.py

a56cdf8

Fix lint issues in test_json.py

5d1cdc8

Fix lint issues in test_json.py fixing spacing issues

2d37610

Fix lint issues in test_json.py, part 3

1933de1

Merge branch 'master' into fix/output-parser-dict-error

ece236e

Fix lint issues in test_json.py, blank space error

92b6883

adding formatting changes

873b3b2

adding formatting changes, recurring blank space error ver1.4

a471947

vercel bot deployed to Preview August 12, 2025 01:58 View deployment

Merge branch 'master' into fix/output-parser-dict-error

5a51e00

mdrxy changed the title ~~fix(core): raise OutputParserException for non-dict JSON outputs~~ fix(core): raise OutputParserException for non-dict JSON outputs Aug 12, 2025

Yash-Tobre added 3 commits August 12, 2025 00:35

Added a tolerence check for different versions.

c599516

Rearranged the imports.

4031df6

reformatted the assertion statement

9ab7363

Yash-Tobre added 5 commits August 12, 2025 00:48

reformatted the memory_stream_file

f30cacf

reformatted the imports, again using ruff

ddabc32

reformatted the imports, again using ruff

8143de6

reformatted the imports, added a blank space

bb726d9

blank space modification in streamer

ea7c05f

Yash-Tobre and others added 3 commits August 12, 2025 14:27

blank space mod using ruff again!

396237c

Merge branch 'master' into fix/output-parser-dict-error

1bdbf55

Merge branch 'master' into fix/output-parser-dict-error

2100f05

mdrxy requested changes Aug 13, 2025

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mdrxy reviewed Aug 13, 2025

View reviewed changes

mdrxy requested changes Aug 13, 2025

View reviewed changes

fix(core): raise OutputParserException for non-dict JSON outputs #32236

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fix(core): raise OutputParserException for non-dict JSON outputs #32236

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Merging #32236 will not alter performance

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fix(core): raise `OutputParserException` for non-dict JSON outputs #32236

fix(core): raise `OutputParserException` for non-dict JSON outputs #32236

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