python view not working after deploying django app -

i attempting deploy new app using apache , mod-wsgi. app takes date provided in post request , plots graph , table specific time range. date appears set correctly using python internal (development) web server, fails when using apache/wsgi. issue appears view;

# set initial date custom_date = [1, 1, 2015]  def getcustomdata(request):     global custom_date     form = dateform()      if request.method == 'post':         custom_date[0] = (str(request.post['custom_date_day']))         custom_date[1] = (str(request.post['custom_date_month']))         custom_date[2] = (str(request.post['custom_date_year']))         date_reformat = datetime.datetime.strptime(str(custom_date[0]+' '+custom_date[1]+' '+custom_date[2]), '%d %m %y')         chart_date = date_reformat.strftime('%-d %b %y')         return render(request, 'custom_results.html', {'cdate': chart_date})      else:         date_reformat = datetime.datetime.strptime(str(custom_date[0]+' '+custom_date[1]+' '+custom_date[2]), '%d %m %y')         chart_date = date_reformat.strftime('%-d %b %y')         return render(request, 'custom_results.html', {'cdate': chart_date}) 

when using apache, initial post request works fine, when attempting navigate page 2 of table, "typeerror: cannot concatenate 'str' , 'int' objects" line following "else" statement. assuming way global data variable gets updated between apache , development server different?

you must never use mutable global variables store data this. variable same users, means 1 user able change display format subsequent users. data should stored in session.

however, cause of problem simpler; default data composed of integers, stored data strings. should use string interpolation rather concatenating, here should store single string anyway.

also note last 3 lines of if block same else block; can simplify view considerably.

def getcustomdata(request):     if request.method == 'post':         request.session['custom_date'] = ' '.join(             request.post['custom_date_day'],             request.post['custom_date_month'],             request.post['custom_date_year']         )     custom_date = request.session.setdefault('custom_date', '1 1 2015')     date_reformat = datetime.datetime.strptime(custom_date, '%d %m %y')     chart_date = date_reformat.strftime('%-d %b %y')     return render(request, 'custom_results.html', {'cdate': chart_date})