fix: Advanced mode in read file component

[HimavarshaVS]

Summary by CodeRabbit

• New Features

  • Added support for S3 storage file validation alongside local storage

• Bug Fixes

  • Improved error handling and messaging during file processing failures
  • Enhanced file path tracking for accurate data provenance throughout document processing
  • Strengthened image validation with expanded exception handling for file system errors

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Walkthrough

The changes enhance error handling and metadata propagation in the Docling file processing pipeline. Improvements include conditional stderr reading on subprocess failure, per-file rollup logic for multi-file processing, storage-type-aware image validation (S3 vs local), and proper file path tracking for error cases.

Changes

Cohort / File(s)	Summary
Docling file processing and error handling src/lfx/src/lfx/components/files_and_knowledge/file.py	Enhanced subprocess error handling with conditional stderr reading; improved metadata propagation by ensuring file_path is set for all error and success cases; added storage-type-aware image validation (S3 via read_file_bytes vs. local filesystem); implemented per-file rollup logic for multi-file processing; added early error payload detection and handling; expanded exception handling for image read/validation; added placeholder Data for empty content; improved handling of advanced_data being None.
Model field access refactoring src/lfx/src/lfx/schema/data.py	Changed instance-level model_fields access to class-level access in Data.__setattr__ by replacing self.model_fields with type(self).model_fields; no external behavior change.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

• file.py: Multiple error handling branches with conditional logic for stderr, payload errors, and per-file rollups; storage-type differentiation for image validation requires careful verification
• data.py: Trivial single-line refactoring but requires context switching; verify that class-level access produces identical behavior in all scenarios

Pre-merge checks and finishing touches

Important

Pre-merge checks failed

Please resolve all errors before merging. Addressing warnings is optional.

❌ Failed checks (1 error, 1 warning)

Check name	Status	Explanation	Resolution
Test Coverage For New Implementations	❌ Error	PR introduces substantial changes to file reading component's advanced mode functionality without adding or updating any test files.	Add comprehensive test coverage in src/lfx/tests/unit/components/files_and_knowledge/ for error handling, metadata propagation, image validation, and advanced Docling handling.
Test Quality And Coverage	⚠️ Warning	Test files lack coverage for PR's main behavioral changes including per-file rollup data handling, advanced_data None handling, S3 vs local storage differentiation, and metadata propagation per-file.	Add comprehensive tests for multiple file processing, mixed success/error scenarios, advanced_data None case, S3 vs local conditional logic, and metadata propagation per-file.

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: Advanced mode in read file component' directly aligns with the primary changes, which focus on advanced mode handling in the file processing component with improved error handling, metadata propagation, and per-file output management.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Test File Naming And Structure	✅ Passed	The PR includes comprehensive test coverage that fully adheres to Langflow testing standards with properly organized test classes and descriptive test names.
Excessive Mock Usage Warning	✅ Passed	Test file demonstrates excellent design with minimal mock usage—only one mock for external Docling subprocess dependency, while remaining 25+ tests use real FileComponent objects and filesystem operations.

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[github-actions]

Frontend Unit Test Coverage Report

Coverage Summary

Lines	Statements	Branches	Functions
	16.64% (4686/28150)	9.99% (2179/21792)	10.93% (676/6181)

Unit Test Results

Tests	Skipped	Failures	Errors	Time
1829	0 💤	0 ❌	0 🔥	23.446s ⏱️

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.09%. Comparing base (b86351f) to head (03b2273).
⚠️ Report is 1 commits behind head on main.

❌ Your project status has failed because the head coverage (39.27%) is below the target coverage (60.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11041      +/-   ##
==========================================
- Coverage   33.11%   33.09%   -0.02%     
==========================================
  Files        1389     1389              
  Lines       65714    65714              
  Branches     9730     9730              
==========================================
- Hits        21760    21748      -12     
- Misses      42836    42848      +12     
  Partials     1118     1118              

Flag	Coverage Δ
backend	52.34% <ø> (-0.07%)	⬇️
frontend	15.34% <ø> (ø)
lfx	39.27% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/lfx/src/lfx/schema/data.py	66.88% <100.00%> (ø)

... and 2 files with indirect coverage changes

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[jordanrfrazier]

What does this change do?

[HimavarshaVS]

previously had this deprecation warning
/app/.venv/lib/python3.12/site-packages/lfx/schema/data.py:212: PydanticDeprecatedSince211: Accessing the 'model_fields' attribute on the instance is deprecated. Instead, you should access this attribute from the model class. Deprecated in Pydantic V2.11 to be removed in V3.0.
elif key in self.model_fields:

This is to fix that warning