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CSVToDocument row mode fails on CR-separated CSV input

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#13,022 0 comments 0 reactions 1 assignee View on GitHub

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@julian-risch is already working on this.

Since Oct 1, 2026.

  • #13026 by @Marcuswang0824 — closed without merging

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
86/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
python
Domain
data

Research direction

Start at the CSVToDocument conversion_mode="row" entry point and inspect how its csv.DictReader receives StringIO input. Run test_csv_to_document.py, then add or update the regression coverage for LF, CRLF, and CR records, quoted multiline fields, and row metadata. Done means all 20 tests pass and CR-separated input produces the expected documents.

Written by the indexing model from the issue text.

Description

P3

Describe the bug

CSVToDocument(conversion_mode="row") raises _csv.Error for CSV input whose records are separated by carriage returns (\r). The same input with LF or CRLF separators produces the expected documents. This was found with a local reproduction on current main, not a production incident.

To reproduce

from haystack.components.converters import CSVToDocument
from haystack.dataclasses import ByteStream

source = ByteStream(data=b"text,author\rfirst,Ada\rsecond,Bob\r")
result = CSVToDocument(conversion_mode="row").run(
    sources=[source], content_column="text"
)
print([doc.content for doc in result["documents"]])

Actual behavior

_csv.Error: new-line character seen in unquoted field - do you need to open the file with newline=''?

The error occurs while reading reader.fieldnames.

Expected behavior

The result should contain ['first', 'second'], with the corresponding author metadata and row numbers 0 and 1. Quoted multiline fields should retain their original newline characters.

Root cause and proposed fix

The converter passes io.StringIO(data) to csv.DictReader. Its default newline setting does not split CR-separated records. Passing io.StringIO(data, newline="") lets the CSV reader handle the line endings without translating quoted field content, consistent with Python's CSV input guidance.

A small local patch and regression test are ready. Before the fix, the parameterized LF/CRLF/CR test gives 1 failed / 2 passed; after the fix, all 20 tests in test_csv_to_document.py pass. The test also checks quoted multiline content and row metadata.

System

  • macOS arm64, Python 3.12.14
  • Haystack 3.3.0-rc0, main at bb5b39f42edb5cd9f69e5d9025d48d389c08598f
  • Official Hatch test environment; no model, GPU, or external API required

AI assistance: Codex generated this report, the reproduction, and the proposed patch, and ran the local checks.

Dominant language
Python
Stars
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Forks
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Avg merge
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Merged PRs (30d)
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