python - 为什么这个 Python 函数不返回 future ？

Question

我将 Google App Engine 与 NDB 结合使用。为了简洁起见，我删除了很多代码，但保留了基本问题。我遇到错误 'list' object has no attribute 'get_result'

def get_future(keys):
    future = ndb.get_multi_async(keys)
    important_value = ... # get important value
    return {"future" : future, "value" : important_value}

dic = get_future(keys)
future = dic['future']
# error `'list' object has no attribute 'get_result'`
items = future.get_result()

为什么我应该得到一个 future 却得到一个列表？

Answer 1

get_multi_async 实际上返回 future 对象的列表，因此您需要对这些对象调用 .get_result()。

Official definition :

ndb.get_multi_async(keys, **ctx_options)

Asynchronously fetches entities identified by the passed sequence of keys.

Arguments

keys
 -Sequence of keys

**ctx_options 
 -Context options 

Returns a list of Future objects. Each future's result is a Model instance or None if the key wasn't found.