REG: read_excel with engine specified raises on non-path/non-buffer (#39586)

Author: rhshadrach

doc/source/whatsnew/v1.2.2.rst

@@ -23,6 +23,7 @@ Fixed regressions
 - Fixed regression in :meth:`~DataFrame.to_csv` opening ``codecs.StreamWriter`` in binary mode instead of in text mode and ignoring user-provided ``mode`` (:issue:`39247`)
 - Fixed regression in :meth:`DataFrame.transform` failing in case of an empty DataFrame or Series (:issue:`39636`)
 - Fixed regression in :meth:`core.window.rolling.Rolling.count` where the ``min_periods`` argument would be set to ``0`` after the operation (:issue:`39554`)
+- Fixed regression in :func:`read_excel` that incorrectly raised when the argument ``io`` was a non-path and non-buffer and the ``engine`` argument was specified (:issue:`39528`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/io/excel/_base.py

@@ -1069,26 +1069,37 @@ def __init__(
 
  xlrd_version = LooseVersion(get_version(xlrd))
 
- if xlrd_version is not None and isinstance(path_or_buffer, xlrd.Book):
- ext = "xls"
- else:
- ext = inspect_excel_format(
- content_or_path=path_or_buffer, storage_options=storage_options
- )
-
+ ext = None
  if engine is None:
+ # Only determine ext if it is needed
+ if xlrd_version is not None and isinstance(path_or_buffer, xlrd.Book):
+ ext = "xls"
+ else:
+ ext = inspect_excel_format(
+ content_or_path=path_or_buffer, storage_options=storage_options
+ )
+
  # ext will always be valid, otherwise inspect_excel_format would raise
  engine = config.get_option(f"io.excel.{ext}.reader", silent=True)
  if engine == "auto":
  engine = get_default_engine(ext, mode="reader")
 
- if engine == "xlrd" and ext != "xls" and xlrd_version is not None:
- if xlrd_version >= "2":
+ if engine == "xlrd" and xlrd_version is not None:
+ if ext is None:
+ # Need ext to determine ext in order to raise/warn
+ if isinstance(path_or_buffer, xlrd.Book):
+ ext = "xls"
+ else:
+ ext = inspect_excel_format(
+ path_or_buffer, storage_options=storage_options
+ )
+
+ if ext != "xls" and xlrd_version >= "2":
  raise ValueError(
  f"Your version of xlrd is {xlrd_version}. In xlrd >= 2.0, "
  f"only the xls format is supported. Install openpyxl instead."
  )
- else:
+ elif ext != "xls":
  caller = inspect.stack()[1]
  if (
  caller.filename.endswith(

pandas/io/excel/_openpyxl.py

@@ -533,15 +533,19 @@ def get_sheet_data(self, sheet, convert_float: bool) -> List[List[Scalar]]:
 
  version = LooseVersion(get_version(openpyxl))
 
- if version >= "3.0.0":
+ # There is no good way of determining if a sheet is read-only
+ # https://foss.heptapod.net/openpyxl/openpyxl/-/issues/1605
+ is_readonly = hasattr(sheet, "reset_dimensions")
+
+ if version >= "3.0.0" and is_readonly:
  sheet.reset_dimensions()
 
  data: List[List[Scalar]] = []
  for row_number, row in enumerate(sheet.rows):
  converted_row = [self._convert_cell(cell, convert_float) for cell in row]
  data.append(converted_row)
 
- if version >= "3.0.0" and len(data) > 0:
+ if version >= "3.0.0" and is_readonly and len(data) > 0:
  # With dimension reset, openpyxl no longer pads rows
  max_width = max(len(data_row) for data_row in data)
  if min(len(data_row) for data_row in data) < max_width:

pandas/tests/io/excel/test_openpyxl.py

@@ -122,6 +122,17 @@ def test_to_excel_with_openpyxl_engine(ext):
  styled.to_excel(filename, engine="openpyxl")
 
 
+@pytest.mark.parametrize("read_only", [True, False])
+def test_read_workbook(datapath, ext, read_only):
+ # GH 39528
+ filename = datapath("io", "data", "excel", "test1" + ext)
+ wb = openpyxl.load_workbook(filename, read_only=read_only)
+ result = pd.read_excel(wb, engine="openpyxl")
+ wb.close()
+ expected = pd.read_excel(filename)
+ tm.assert_frame_equal(result, expected)
+
+
 @pytest.mark.parametrize(
  "header, expected_data",
  [
@@ -139,13 +150,22 @@ def test_to_excel_with_openpyxl_engine(ext):
 @pytest.mark.parametrize(
  "filename", ["dimension_missing", "dimension_small", "dimension_large"]
 )
-@pytest.mark.xfail(
- LooseVersion(get_version(openpyxl)) < "3.0.0",
- reason="openpyxl read-only sheet is incorrect when dimension data is wrong",
-)
-def test_read_with_bad_dimension(datapath, ext, header, expected_data, filename):
+# When read_only is None, use read_excel instead of a workbook
+@pytest.mark.parametrize("read_only", [True, False, None])
+def test_read_with_bad_dimension(
+ datapath, ext, header, expected_data, filename, read_only, request
+):
  # GH 38956, 39001 - no/incorrect dimension information
+ version = LooseVersion(get_version(openpyxl))
+ if (read_only or read_only is None) and version < "3.0.0":
+ msg = "openpyxl read-only sheet is incorrect when dimension data is wrong"
+ request.node.add_marker(pytest.mark.xfail(reason=msg))
  path = datapath("io", "data", "excel", f"{filename}{ext}")
- result = pd.read_excel(path, header=header)
+ if read_only is None:
+ result = pd.read_excel(path, header=header)
+ else:
+ wb = openpyxl.load_workbook(path, read_only=read_only)
+ result = pd.read_excel(wb, engine="openpyxl", header=header)
+ wb.close()
  expected = DataFrame(expected_data)
  tm.assert_frame_equal(result, expected)

pandas/tests/io/excel/test_readers.py

@@ -2,6 +2,7 @@
 from functools import partial
 import os
 from urllib.error import URLError
+from zipfile import BadZipFile
 
 import numpy as np
 import pytest
@@ -685,7 +686,13 @@ def test_missing_file_raises(self, read_ext):
 
  def test_corrupt_bytes_raises(self, read_ext, engine):
  bad_stream = b"foo"
- with pytest.raises(ValueError, match="File is not a recognized excel file"):
+ if engine is None or engine == "xlrd":
+ error = ValueError
+ msg = "File is not a recognized excel file"
+ else:
+ error = BadZipFile
+ msg = "File is not a zip file"
+ with pytest.raises(error, match=msg):
  pd.read_excel(bad_stream)
 
  @tm.network