Emit unformatted output when formatting fails by koxudaxi · Pull Request #2737 · koxudaxi/datamodel-code-generator

koxudaxi · 2025-12-22T14:42:18Z

Summary by CodeRabbit

Bug Fixes
- Code formatting errors are now handled gracefully; unformatted code is emitted instead of causing failures, with warnings logged.
Tests
- Added tests to verify fallback behavior when code formatting fails.

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coderabbitai · 2025-12-22T14:42:24Z

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📥 Commits

Reviewing files that changed from the base of the PR and between 475e407 and 4e49b06.

📒 Files selected for processing (1)

tests/main/test_main_general.py

Walkthrough

The changes add graceful error handling for code formatting failures. When code formatting raises an exception, a warning is logged and unformatted code is emitted instead of failing completely. This includes wrapping formatting calls in try/except blocks in the base parser and adding new tests to verify this fallback behavior.

Changes

Cohort / File(s)	Summary
Error handling in parser `src/datamodel_code_generator/parser/base.py`	Wraps `code_formatter.format_code()` calls with try/except blocks in `_generate_module_output` and `_generate_empty_init_exports` methods. When formatting fails, a UserWarning is logged and unformatted body is returned instead of propagating the exception.
Test coverage for formatting fallback `tests/main/test_main_general.py`	Updated import to include `CodeFormatter`; added `test_format_code_fallback_on_error` and `test_format_code_fallback_on_error_init_exports` test cases that mock formatter failure, verify warning emission, and assert unformatted output is produced.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Specific areas requiring attention:
- Logic of try/except blocks in _generate_module_output and _generate_empty_init_exports—verify exception types caught are appropriate and warnings convey sufficient context
- Mock setup in tests—confirm CodeFormatter.format_code mocking properly simulates real formatting failure scenarios
- Output validation in tests—ensure assertions on unformatted output (e.g., presence of "class Model", "name:", and exports indicators) align with actual generated code structure

Poem

🐰 When formatters fail and syntax breaks,
A gentle warning the rabbit makes,
Unformatted code, though rough and bare,
Helps debug the mess with loving care! ✨

Pre-merge checks and finishing touches

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	The PR implements fallback to unformatted output when formatting fails, but issue #2315 explicitly requests a --skip-formatting CLI option that allows skipping formatting entirely, not just on failure.	Implement the requested --skip-formatting CLI option and generate.skip_formatting parameter to allow intentional skipping of formatting, as described in issue #2315.
Docstring Coverage	⚠️ Warning	Docstring coverage is 71.43% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: wrapping code formatting calls with try/except to emit unformatted output when formatting fails.
Out of Scope Changes check	✅ Passed	All changes are focused on implementing graceful formatting failure handling and related tests, which are within the intended scope of addressing formatting issues.

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Actionable comments posted: 0

🧹 Nitpick comments (1)

src/datamodel_code_generator/parser/base.py (1)

2840-2847: Consider adjusting stacklevel for better warning context.

The warning uses stacklevel=1, which points to this line in base.py rather than the user's call site. Using stacklevel=2 or higher would provide users with more helpful context about where in their code the formatting failure occurred.

Additionally, this try/except pattern is duplicated at lines 2876-2883. Consider extracting a helper method like _safe_format_code(code: str, formatter: CodeFormatter) -> str to reduce duplication.

🔎 Proposed refactor to reduce duplication

+    def _safe_format_code(self, body: str, code_formatter: CodeFormatter) -> str:
+        """Apply code formatting with graceful fallback on error."""
+        try:
+            return code_formatter.format_code(body)
+        except Exception as exc:  # noqa: BLE001
+            warn(
+                f"Failed to format code: {exc!r}. Emitting unformatted output.",
+                stacklevel=3,
+            )
+            return body
+
     def _generate_module_output(...):
         ...
         body = "\n".join(result)
         if config.code_formatter:
-            try:
-                body = config.code_formatter.format_code(body)
-            except Exception as exc:  # noqa: BLE001
-                warn(
-                    f"Failed to format code: {exc!r}. Emitting unformatted output.",
-                    stacklevel=1,
-                )
+            body = self._safe_format_code(body, config.code_formatter)

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📥 Commits

Reviewing files that changed from the base of the PR and between 2b4af3e and 475e407.

📒 Files selected for processing (2)

src/datamodel_code_generator/parser/base.py
tests/main/test_main_general.py

🧰 Additional context used

🧬 Code graph analysis (2)

src/datamodel_code_generator/parser/base.py (1)

src/datamodel_code_generator/format.py (1)

format_code (272-291)

tests/main/test_main_general.py (2)

src/datamodel_code_generator/format.py (2)

CodeFormatter (162-332)

PythonVersion (56-119)

src/datamodel_code_generator/__init__.py (3)

generate (393-859)

InputFileType (195-205)

AllExportsScope (249-257)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (9)

GitHub Check: 3.11 on macOS
GitHub Check: 3.14 on macOS
GitHub Check: 3.11 on Windows
GitHub Check: 3.10 on Windows
GitHub Check: 3.12 on Windows
GitHub Check: 3.14 on Windows
GitHub Check: 3.13 on Windows
GitHub Check: benchmarks
GitHub Check: Analyze (python)

🔇 Additional comments (3)

tests/main/test_main_general.py (3)

21-21: LGTM!

Import of CodeFormatter is appropriate for mocking in the new fallback tests.

1095-1117: Comprehensive test coverage for formatting fallback.

The test appropriately mocks the formatter to raise an exception, verifies the warning is emitted, and confirms that unformatted output is produced. Good coverage of the happy path for the fallback behavior.

1119-1140: Good coverage of init.py formatting fallback.

This test effectively covers the second code path where formatting can fail (in _generate_empty_init_exports). Using OpenAPI with AllExportsScope.Children is an appropriate way to exercise this path.

codecov · 2025-12-22T14:51:03Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.36%. Comparing base (2b4af3e) to head (4e49b06).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2737   +/-   ##
=======================================
  Coverage   99.36%   99.36%           
=======================================
  Files          83       83           
  Lines       12123    12165   +42     
  Branches     1458     1459    +1     
=======================================
+ Hits        12046    12088   +42     
  Misses         45       45           
  Partials       32       32

Flag	Coverage Δ
unittests	`99.36% <100.00%> (+<0.01%)`	⬆️

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codspeed-hq · 2025-12-22T14:53:46Z

CodSpeed Performance Report

Merging #2737 will not alter performance

_{Comparing feature/emit-unformatted-output-on-formatting-failure (4e49b06) with main (2b4af3e)}

Summary

✅ 70 untouched
⏩ 10 skipped¹

10 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

Emit unformatted output when formatting fails

5d4b8a1

Merge main and resolve conflicts

475e407

coderabbitai Bot reviewed Dec 22, 2025

View reviewed changes

Add test for init exports without formatting

4e49b06

koxudaxi merged commit 522101a into main Dec 22, 2025
37 checks passed

koxudaxi deleted the feature/emit-unformatted-output-on-formatting-failure branch December 22, 2025 15:03

coderabbitai Bot mentioned this pull request Dec 24, 2025

Optimize Jinja2 environment caching and ruff batch formatting #2779

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Emit unformatted output when formatting fails#2737

Emit unformatted output when formatting fails#2737
koxudaxi merged 3 commits intomainfrom
feature/emit-unformatted-output-on-formatting-failure

koxudaxi commented Dec 22, 2025 •

edited by coderabbitai Bot

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koxudaxi commented Dec 22, 2025 •

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