InvalidDocument: Cannot encode object: ObjectId('51861bc79bb6550f2b98be23')

Question

I have been using mongo for a while know (with python, mongo 2.4.4 64 bit, OS X 10.8.2, pymongo 2.5.2, python 2.7.2), and I observed a strange behaviour. Sometimes it throws following exception when trying to insert a document into a collection:

Cannot encode object: ObjectId('51861bc79bb6550f2b98be23')

... "/Users/nutrina/www/env_pdf_admin_apache/lib/python2.7/site-packages/pymongo/collection.py", line 266, in save return self.insert(to_save, manipulate, safe, check_keys, **kwargs) File "/Users/nutrina/www/env_pdf_admin_apache/lib/python2.7/site-packages/pymongo/collection.py", line 357, in insert continue_on_error, self.__uuid_subtype), safe) InvalidDocument: Cannot encode object: ObjectId('51861bc79bb6550f2b98be23')

I have no idea why this is happening. Did anybody else encounter this error, or does somebody have an idea what could cause it?

Update: The object I am trying to save has following structure:

{
   'is_open': true,   // boolean
   'data': {
      'user_id': ObjectId(...), // ObjectId
      'user_type': 1,           // Integer
   }
}

The error is reported for the field *user_id*, but I am pretty sure that value is a valid ObjectId. This is the '_id' of an object (user) from another collection (users). And the save operation succeeds for the same value most of the time.

Thanks, Gerald

Is there anything else about the object you're trying to save that you could share? What type of data does it contain? — WiredPrairie
I have update the description of the problem. @lovesh: I don't think that problem is related. — nutrina
to revive an old question: what are you giving to the ObjectId constructor? Is it a string? Is there any chance it has some odd characters in it, like a trailing null char, newline, ...? — drevicko
@drevicko: it turned out that the configuration of the wsgi web app where this was implemented was the problem (I think the WSGIProcessGroup and WSGIApplicationGroup where not set right). The document I tried to save was fine. I found the information for this here: api.mongodb.org/python/current/examples/…. There was however an older version of pymongo that was running, not 2.7 which is documented at the link above. — nutrina

Xiaoji Liu Xiaoji Liu · Accepted Answer · 2016-01-04T16:31:12

Python integers are stored as arbitrary precision numbers, which is not supported by Mongodb. You need to convert them into normal int64 or string objects first.

InvalidDocument: Cannot encode object: ObjectId('51861bc79bb6550f2b98be23')

2 Answers