update_cells no longer supports non-contiguous cells (overwrites unlisted cells within the range)

This appears to be a regression in the gpsread use of the v4 API (was previously working: see #177)

Environment info

Operating System: Windows / Linux Python version: 2.7.14 gspread version: 2.1.1

Steps to reproduce

1. Make a list of cells that are non-contiguous, e.g. [<Cell R7C2 ‘2018’>, <Cell R20C2 ‘2004’>]
2. Call update_cells, passing the list
3. Cells R7C2 through R20C2 inclusive get updated, with only R7C2 and R20C2 having values, R8-R19C2 all get zeroed out.

Stack trace or other output that would be helpful

Compare update_cells implementation in /v4/models.py with models.py

>>> worksheet.range('B7:B20')
[<Cell R7C2 ''>, <Cell R8C2 ''>, <Cell R9C2 u'2013'>, <Cell R10C2 u'2013'>, <Cell R11C2 u'2015'>, <Cell R12C2 u'2015'>, <Cell R13C2 ''>, <Cell R14C2 u'2017'>, <Cell R15C2 u'2015'>, <Cell R16C2 u'2017'>, <Cell R17C2 u'2016'>, <Cell R18C2 u'2014'>, <Cell R19C2 u'2012'>, <Cell R20C2 ''>]
>>> cells = worksheet.range('B7:B20')
>>> other_cells = []
>>> other_cells.append(cells[0])
>>> other_cells.append(cells[len(cells)-1])
>>> other_cells
[<Cell R7C2 ''>, <Cell R20C2 ''>]
>>> other_cells[0].value = "test"
>>> other_cells[1].value = "testing"
>>> len(other_cells)
2
>>> worksheet.update_cells(other_cells)
{u'spreadsheetId': u'**removed**', u'updatedRange': u'Collection!B7:B20', u'updatedCells': 14, u'updatedRows': 14, u'updatedColumns': 1}
>>> worksheet.range('B7:B20')
[<Cell R7C2 u'test'>, <Cell R8C2 ''>, <Cell R9C2 ''>, <Cell R10C2 ''>, <Cell R11C2 ''>, <Cell R12C2 ''>, <Cell R13C2 ''>, <Cell R14C2 ''>, <Cell R15C2 ''>, <Cell R16C2 ''>, <Cell R17C2 ''>, <Cell R18C2 ''>, <Cell R19C2 ''>, <Cell R20C2 u'testing'>]

[burnash]

@CianH thank you for reporting the issue. It was fixed in #553 and released in version 3.0.1 on pypi. Please upgrade the library and check.

@AlexRiina thank you very much for the hint and comments. @ADraginda thank you again for the pull request with the fix.

I’m closing this issue now.

[ADraginda]

@CianH Using @AlexRiina 's suggestion, I verified that setting to None does work. I’ll be submitting a PR, but in the interim you can workaround the issue by setting the .value for every cell to None before doing your actual value setting. If you do that, then only your changes will be applies.