fix csv file reader (#2248)

* fix

* fix test with inline content

* fix format

Author: dayesouza

.semversioner/next-release/patch-20260225001919068435.json

@@ -0,0 +1,4 @@
+{
+  "type": "patch",
+  "description": "fix csv reader"
+}

packages/graphrag-input/graphrag_input/csv.py

@@ -4,6 +4,7 @@
 """A module containing 'CSVFileReader' model."""
 
 import csv
+import io
 import logging
 import sys
 
@@ -39,6 +40,6 @@ async def read_file(self, path: str) -> list[TextDocument]:
         """
         file = await self._storage.get(path, encoding=self._encoding)
 
-        reader = csv.DictReader(file.splitlines())
+        reader = csv.DictReader(io.StringIO(file))
         rows = list(reader)
         return await self.process_data_columns(rows, path)

tests/unit/indexing/input/test_csv_loader.py

@@ -54,3 +54,26 @@ async def test_csv_loader_multiple_files():
     reader = create_input_reader(config, storage)
     documents = await reader.read_files()
     assert len(documents) == 4
+
+
+async def test_csv_loader_preserves_multiline_fields(tmp_path):
+    """Multiline quoted CSV fields must retain their internal newlines."""
+    csv_content = (
+        "title,text\r\n"
+        '"Post 1","Line one.\nLine two.\nLine three."\r\n'
+        '"Post 2","Single line."\r\n'
+    )
+    (tmp_path / "input.csv").write_text(csv_content, encoding="utf-8")
+    config = InputConfig(
+        type=InputType.Csv,
+        text_column="text",
+        title_column="title",
+    )
+    storage = create_storage(StorageConfig(base_dir=str(tmp_path)))
+    reader = create_input_reader(config, storage)
+    documents = await reader.read_files()
+    assert len(documents) == 2
+    assert documents[0].title == "Post 1"
+    assert documents[0].text == "Line one.\nLine two.\nLine three."
+    assert documents[1].title == "Post 2"
+    assert documents[1].text == "Single line."