（1）报错情况如下：
DoesNotExist: Publisher matching query does not exist.
（2）处理方法：
try:
p = Publisher.objects.get(name=‘Apress‘)
except Publisher.DoesNotExist:
print "Apress isn‘t in the database yet."
else:
print "Apress is in the database."
django在读取数据库时未筛选到符合条件的记录会报错
原文：http://www.cnblogs.com/stuqx/p/7383753.html
