`.xlsm` files are like `.xlxs` files but with macros enabled. They store
data in the same XML-based format as `.xlsx` files.
Pyexcel will try to use the xlrd package to parse `.xlsm` files. This
used to work because xlrd used to support reading `.xlsx` files. xlrd
has dropped support for `.xlsx` files in version 2 because of security
concerns. This means that when pyexcel asks xlrd to parse a `.xlsm` file
it causes an error.
This commit adds some branching to force `.xlsm` files to be opened
with pyexcel-xlsx instead, which does support `.xlsx` files.
xlrd is a library for reading data and formatting information from
Excel files in the historical .xls format.
Version 2 of xlrd no longer supports anything other than .xls files.
We were using it to also support reading .xlsm files (old Excel files
with macro support).
We could keep using the old version of this dependency, but hopefully
this niche version of an ancient file format is obscure enough that
no-one is using it, and we can drop support, keeping our dependencies
up to date.
We require users to export their spreadsheets as CSV files before
uploading them. But this seems like the sort of thing a computer should
be able to do.
So this commit adds a wrapper class which:
- takes a the uploaded file
- returns it in a normalised format, or reads it using pyexcel[1]
- gives the data back in CSV format
This allows us to accept `.csv`, `.xlsx`, `.xls` (97 and 95), `.ods`,
`.xlsm` and `.tsv` files. We can upload the resultant CSV just like
normal, and process it for errors as before.
Testing
---
To test this I’ve added a selection of common spreadsheet files as test
data. They all contain the same data, so the tests look to see that the
resultant CSV output is the same for each.
UI changes
---
This commit doesn’t change the UI, apart from to give a different error
message if a user uploads a file type that we still don’t understand.
I intend to do this as a separate pull request, in order to fulfil
https://www.pivotaltracker.com/story/show/119371637
