Convert SpreadSheets to CSV files with Python and pyuno, Part 2

Using the SSConverter class that we developed last week, which used the OORunner class from the week before that, this week we'll create a Python function that allows us to use spreadsheets as if they were CSV files by converting them on the fly.

Unlike the previous two pieces of code this piece doesn't use any new features of pyuno. It's actually quite simple: the function takes the name of a file that can be either a spreadsheet file or a CSV file:

  • If the name refers to a spreadsheet file then the corresponding CSV file is checked, if it does not exist it is created. If it does exist, then it is checked to make sure that it's newer than the spreadsheet file, if not it's re-created.
  • If the name refers to a CSV file then it's again checked to make sure it's newer than the spreadsheet file and it's re-created if the spreadsheet is newer.

In either case the name of the CSV file is returned. Usage is simple:

csvfile = check_csv_file(ifile)

If run directly the test code runs which accepts any number of command line arguments. The test code calls the function on each command line argument.

When run on a spreadsheet when there is no CSV file it creates the CSV file and returns its name:

$ python check_csv_file.py jj.xls
Creating jj.csv from jj.xls
Input name jj.xls, output name jj.csv

When run on the same spreadsheet again it simply returns the CSV file name since the CSV file already exists and is newer than the spreadsheet:

$ python check_csv_file.py jj.xls
Input name jj.xls, output name jj.csv

When run on the CSV file it returns the CSV file name:

$ python check_csv_file.py jj.csv
Input name jj.csv, output name jj.csv

When run on the CSV file after the spreadsheet has been modified it re-creates the CSV file and returns its name:

$ touch jj.xls
$ python check_csv_file.py jj.csv
Recreating jj.csv from jj.xls
Input name jj.csv, output name jj.csv

The source code for the function follows:

import os
import re
import sys
import csv


def check_csv_file(csvfile):
    """
    Make sure the CSV file exists.
    If it does not exist, try to create it from an XLS or ODS file.
    The passed name can refer to an XLS file or an ODS file.
    The return value will be the name of a CSV file.
    """
    def find_csv(csvf):
        """ Check to see if the CSV file exists. """
        fname, ext = os.path.splitext(csvf)
        ext        = ext.lower()
        if   ext == '.txt':
            f = '%s.%s' % (fname, 'TXT')
            if os.path.exists(f):
                csvf = f
            else:
                csvf = '%s.%s' % (fname, 'txt')

        elif ext != '.csv':
            f = '%s.%s' % (fname, 'CSV')
            if os.path.exists(f):
                csvf = f
            else:
                csvf = '%s.%s' % (fname, 'csv')

        return csvf

    def find_sheet(ssvf):
        """ Check to see if the spread sheet file exists. """
        sheetf = None
        fname  = os.path.splitext(ssvf)[0]
        for ext in ('xls', 'XLS', 'ods', 'ODS'):
            f = '%s.%s' % (fname, ext)
            if os.path.exists(f):
                sheetf = f
                break

        return sheetf

    def convert_sheet(sheetf, csvf):
        """ Convert spreadsheet to a CSV file. """
        import ooutils
        from ssconverter import SSConverter
        try:
            converter = SSConverter()
            converter.convert(sheetf, csvf)
        except Exception, e:
            sys.stderr.write("ERROR: %s\n" % e.message)
            sys.exit(1)

    # Find the spreadsheet file that corresponds to the CSV file
    csvfile   = find_csv(csvfile)
    sheetfile = find_sheet(csvfile)

    if sheetfile:
        # If CSV does not exist try to create it.
        if not os.path.exists(csvfile):
            sys.stderr.write("Creating %s from %s\n" % (csvfile, sheetfile))
            convert_sheet(sheetfile, csvfile)
        else:
            # If spreadsheet is newer the CSV file, re-create it.
            if os.stat(csvfile).st_mtime < os.stat(sheetfile).st_mtime:
                sys.stderr.write("Recreating %s from %s\n" % (csvfile, sheetfile))
                convert_sheet(sheetfile, csvfile)


    if not os.path.exists(csvfile):
        sys.stderr.write('File not found: %s\n' % csvfile)
        sys.exit(1)

    return csvfile


if __name__ == "__main__":
    for f in sys.argv[1:]:
        f2 = check_csv_file(f)
        print "Input name %s, output name %s" % (f, f2)
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