这是我编写的一个简单函数.希望对您有帮助.

this is a simple function I have written. Hope it will help you.

def onchange_return_date(self, cr, uid, ids, issuedate, returndate):
 a=datetime.strptime(issuedate,"%Y-%m-%d")
 b=datetime.strptime(returndate,"%Y-%m-%d")
 timedelta = b - a
 diff=timedelta.days
 return {'value': {'days':diff}}