XLRD, check if one sheet doesn't exist else check for another

Question

Trying to read in an series of xls files. They aren't formatted in a uniform manner. Sometimes the sheets exist, sometimes they don't. Sometimes they have one name, sometimes another. It's an imperfect world.

Some code I've tried to check for the sheet name:

import xlrd

wb=xlrd.open_workbook(r'C:\sample.xls')

class Workbook_Reading:

    def __init__(self, wb):
        self.wb = wb
        self.history = None

    def purch_hist(self):
        if self.wb.sheet_loaded('Purchase History') is True:
            purchase_history = wb.sheet_by_name('Purchase History')
            self.history = purchase_history
        elif self.wb.sheet_loaded('Previous Purchases') is True:
            purchase_history = wb.sheet_by_name('Previous Purchases')
            self.history = purchase_history
        else:
            pass

I keep getting an error: xlrd.bffh.XLRDError: No Sheet Named <'Purchase History'>. I am testing this one a wb that I know specifically doesn't have the first condition (purchase history sheet), but has the other (previous purchases sheet). What did I do wrong?

Answer 1

This might help

import xlrd

class Workbook_Reading:

    def __init__(self, wb):
        self.history = None
        self.desiredSheetNames = ['Purchase History', 'Previous Purchases']
        self.availableSheetNames = []
        self.wb = xlrd.open_workbook(r'C:\\sample.xls')
        self.set_available_sheets()

    def set_available_sheets(self):
        for sheetName in self.desiredSheetNames:
            try:
                sheet = self.wb.sheet_by_name(sheetName)
                self.availableSheetNames.append(sheetName)
            except:
                pass

    def purch_hist(self):
        if 'Purchase History' in self.availableSheetNames:
            purchase_history = wb.sheet_by_name('Purchase History')
            self.history = purchase_history
        elif 'Previous Purchases') in self.availableSheetNames:
            purchase_history = wb.sheet_by_name('Previous Purchases')
            self.history = purchase_history
        else:
            pass