openpyxl: merged_cell_ranges and merged_cells are both empty

Question

I have a newly created xlsx workbook with one sheet. A1:A2 is merged and contains the string 'test'.

Using openpyxl (2.3.0) I can access the sheet and the cell value but worksheet.merged_cell_ranges and worksheet.merged_cells are both empty:

wb = workbook.worksheets[0] # ReadOnlyWorksheet: <ReadOnlyWorksheet "Sheet1">
wb.cell(row=1, column=1) # 'test'
wb.merged_cell_ranges # list: []
wb.merged_cells # set: set([])

The documentation (http://openpyxl.readthedocs.org/en/latest/api/openpyxl.worksheet.html) and answers to other SO questions indicate that this is not the expected behaviour.

Yes, the cells are definitely merged. Am I doing something wrong?

Answer 1

The merged_cells and merged_cell_ranges properties are not populated when the workbook has been opened in read-only mode.

Prompted by Charlie Clark's comment, I opened the workbook without the read-only flag and the merged_cells and merged_cell_ranges properties were correctly populated.

Submitted bug #540.