python - 在 mongodb 中存储对象值

Question

我在 python 中获取了一些对象值，我想将其存储在 mongodb 中供以后使用，但没有成功

def callPylink(self):
    from pylinkgrammar.linkgrammar import Parser
    import sys
    p = Parser()
    linkage = p.parse_sent("When was Gandhi born")
    try:
        print "Linkage 0 ", linkage[0]
    except:
        print "error"
    self.collection.insert(linkage[0].__dict__)

在插入行:

Linkage 0 <pylinkgrammar.linkgrammar.Linkage object at 0x92db84c>

Traceback (most recent call last):
  File "objmongo.py", line 28, in <module>
    data = obj.callPylink()
  File "objmongo.py", line 23, in callPylink
    self.collection.insert(linkage[0].__dict__)
  File "/usr/local/lib/python2.7/dist-packages/pymongo/collection.py", line 409, in insert
    gen(), check_keys, self.uuid_subtype, client)
bson.errors.InvalidDocument: Cannot encode object: <S: When, was>

在 mongo 中存储 python 对象的其他方法是什么。

更新

    pickled = pickle.dumps(linkage[0])
    self.collection.insert(pickled)

给出错误:

  File "objmongo.py", line 30, in <module>
    data = obj.callPylink()
  File "objmongo.py", line 25, in callPylink
    self.collection.insert(pickled)
  File "/usr/local/lib/python2.7/dist-packages/pymongo/collection.py", line 409, in insert
    gen(), check_keys, self.uuid_subtype, client)
  File "/usr/local/lib/python2.7/dist-packages/pymongo/collection.py", line 386, in gen
    doc['_id'] = ObjectId()
TypeError: 'str' object does not support item assignment

Answer 1

要在 mongodb 中存储字典，您的字典只能包含字符串键和 mongodb 可以序列化(编码)的那些类型的值。这里不是这种情况。

您可以将复杂的对象树序列化为字节字符串，然后使用 pickle 将它们反序列化回来模块，使用pickle.dumps(obj)将对象序列化为字节串，使用pickle.loads(bytestring)反序列化对象

示例:给定以下类和实例

>>> class OurClass():
...     def __init__(self, arg):
...         self.arg = arg
... 
>>> instance = OurClass(42)

我们导入 pickle 模块

>>> import pickle
>>> pickled = pickle.dumps(y)
>>> pickled
b'\x80\x03c__main__\nX\nq\x00)\x81q\x01}q\x02X\x03\x00\x00\x00argq\x03K*sb.'

pickled 是存储到数据库文档字段中的值，例如:

my_doc = { 'linkage': pickled }
self.collection.insert(my_doc)

现在您可以使用 pickle.loads 恢复原始值

>>> restored = pickle.loads(pickled)
>>> restored
<__main__.OurClass object at 0x7fc91cb35cf8>
>>> restored.arg
42