Python openpyxl data_only=True returning None

Question

I have a simple excel file: A1 = 200 A2 = 300 A3 = =SUM(A1:A2)

this file works in excel and shows proper value for SUM, but while using openpyxl module for python I cannot get value in data_only=True mode

Python code from shell:

wb = openpyxl.load_workbook('writeFormula.xlsx', data_only = True)
sheet = wb.active
sheet['A3']
<Cell Sheet.A3> # python response
print(sheet['A3'].value)
None # python response

while:

wb2 = openpyxl.load_workbook('writeFormula.xlsx')
sheet2 = wb2.active
sheet2['A3'].value
'=SUM(A1:A2)'  # python response

any suggestions what am I doing worng?

Answer 1

It depends upon the provenance of the file. data_only=True depends upon the value of the formula being cached by an application like Excel. If, however, the file was created by openpyxl or a similar library, then it's probable that the formula was never evaluated and, thus, no cached value is available and openpyxl will report None as the value.