filename_or_var = self.args["file"]
if context["request"].GET.has_key(filename_or_var): // filename_or_var was given as url param so it was a var
filename = context["request"].GET[filename_or_var] // use url param value as the file to load
else:
filename = filename_or_var
After Change
// context["request"].GET contains a queryDict of all url parameters.
filename_raw = self.args["file"]
filename_clean = self.substitute(filename_raw,context["request"].GET.items())
project_name = context.page.comicsite.short_name
filename = path.join(settings.DROPBOX_ROOT,project_name,filename_clean)