NDB

Question

我试图酸洗和unpickle结构化数据上酸洗GAE成像这样的ndb.PickleProperty（）属性：

month = MonthRecord.get_or_insert(month_yr_str, parent=ndb.Key('Type','Grocery'), record=pickle.dumps(defaultdict(list_list))) 
names_dict = pickle.loads(month.record) # unpickle for updating 
# ...         # some modifications on names_dict 
month.record = pickle.dumps(names_dict) # pickle 
month.put()        # commit changes 

其中该模型MonthRecord定义为：

class MonthRecord(ndb.Model): 
    record = ndb.PickleProperty() # {name: [[date&time],[expenses]]} 

和list_list为：

def list_list(): # placeholder function needed by pickle at module level 
    return [[],[]] 

第一次运行正常工作（其中插入的情况下被击中的get_or_insert，创建一个新的MonthRe绳索实体）。然而，随后的运行期间（本月内即新的费用记录）出现以下错误：

Traceback (most recent call last): 
    File "C:\GAE_Projects\qb_lite\fin.py", line 31, in update_db 
    names_dict = pickle.loads(month.record) 
    File "C:\Python27\lib\pickle.py", line 1382, in loads 
    return Unpickler(file).load() 
    File "C:\Python27\lib\pickle.py", line 858, in load 
    dispatch[key](self) 
    File "C:\Python27\lib\pickle.py", line 1133, in load_reduce 
    value = func(*args) 
TypeError: __init__() takes exactly 4 arguments (1 given) 

任何想法，错误的原因是什么？

Answer 1

你不必腌你的对象，这将由PickleProperty处理。

相反的：

month = MonthRecord.get_or_insert(
    month_yr_str, 
    parent=ndb.Key('Type','Grocery'), 
    record=pickle.dumps(defaultdict(list_list))) 

做：

month = MonthRecord.get_or_insert(
    month_yr_str, 
    parent=ndb.Key('Type','Grocery'), 
    record=defaultdict(list_list)) 

封装状态将采取的内部照顾。