使用Python Twistar保存/插入多个记录

Question

扩展Twistar示例代码，我试图同时写入多条记录：

from twisted.enterprise import adbapi
from twistar.registry import Registry
from twistar.dbobject import DBObject
from twisted.internet import reactor
class User(DBObject):
     pass
def done(user):
     print "A user was just created with the name %s" % user.first_name
     #The example calls reactor.stop() here
Registry.DBPOOL = adbapi.ConnectionPool('MySQLdb', user="twistar", passwd="apass", db="twistar")
# I've added this function:
def write_user(first_name)
     u = User(first_name=first_name)
     u.save().addCallback(done)
new_users = ["Alice","Bob"]
for new_user in new_users:
     #Here's where I call the function repeatedly:
     write_user(new_user)
reactor.run()

实际上，此示例打印：

A user was just created with the name Alice
A user was just created with the name Bob

但是程序永远不会退出！将reactor.stop()添加到done()函数会导致脚本在仅打印后退出

A user was just created with the name Alice

所以这显然是不对的，但无论如何，这两条记录都被添加到了数据库中。

我该怎么做？

Answer 1

首先，您需要返回u.save()的defer，如下所示：

 def write_user(first_name)
      u = User(first_name=first_name)
      return u.save()

然后，在您的循环中，当您write_user时，您需要存储那些Deferred:

 results = []
 for new_user in new_users:
     results.append(write_user(new_user))
 # Here, all deferred except the last one will call done.
 DeferredList(results[:-1]).addCallback(done)
 # Here, the last Deferred will call reactor.stop after he's done.
 results[-1].addCallback(done).addCallback(reactor.stop) 

这样，只有在保存了最后一个用户后，才能关闭反应器。