Losing merged cells border while editing Excel file with openpyxl

Question

I have two sheets in an Excel file and the first one is a cover sheet which I don\'t need to edit. There are a few merged cells in the cover sheet, and when I edit the file usin

Answer 1

Actual solution is to patch the libraries code by including this snippet after including the library, it fixes the problem. (Note: don't worry about missing definitions, e.g. COORD_RE, i.e. the patch is self-contained)

from itertools import product
import types
import openpyxl
from openpyxl import worksheet
from openpyxl.utils import range_boundaries


def patch_worksheet():
    """This monkeypatches Worksheet.merge_cells to remove cell deletion bug
    https://bitbucket.org/openpyxl/openpyxl/issues/365/styling-merged-cells-isnt-working
    Thank you to Sergey Pikhovkin for the fix
    """

    def merge_cells(self, range_string=None, start_row=None, start_column=None, end_row=None, end_column=None):
        """ Set merge on a cell range.  Range is a cell range (e.g. A1:E1)
        This is monkeypatched to remove cell deletion bug
        https://bitbucket.org/openpyxl/openpyxl/issues/365/styling-merged-cells-isnt-working
        """
        if not range_string and not all((start_row, start_column, end_row, end_column)):
            msg = "You have to provide a value either for 'coordinate' or for\
            'start_row', 'start_column', 'end_row' *and* 'end_column'"
            raise ValueError(msg)
        elif not range_string:
            range_string = '%s%s:%s%s' % (get_column_letter(start_column),
                                          start_row,
                                          get_column_letter(end_column),
                                          end_row)
        elif ":" not in range_string:
            if COORD_RE.match(range_string):
                return  # Single cell, do nothing
            raise ValueError("Range must be a cell range (e.g. A1:E1)")
        else:
            range_string = range_string.replace('$', '')

        if range_string not in self._merged_cells:
            self._merged_cells.append(range_string)


        # The following is removed by this monkeypatch:

        # min_col, min_row, max_col, max_row = range_boundaries(range_string)
        # rows = range(min_row, max_row+1)
        # cols = range(min_col, max_col+1)
        # cells = product(rows, cols)

        # all but the top-left cell are removed
        #for c in islice(cells, 1, None):
            #if c in self._cells:
                #del self._cells[c]

    # Apply monkey patch
    worksheet.Worksheet.merge_cells = merge_cells
patch_worksheet()

Source https://bitbucket.org/openpyxl/openpyxl/issues/365/styling-merged-cells-isnt-working