PyMongo upsert throws "upsert must be an instance of bool" error

I'm running an update on my MongoDB from Python. I have this line:

self.word_counts[source].update({'date':posttime},{"$inc" : words},{'upsert':True})

But it throws this error:

raise TypeError("upsert must be an instance of bool")

But True looks like an instance of bool to me!

How should I correctly write this update?

The third argument to PyMongo's update() is upsert and must be passed a boolean, not a dictionary. Change your code to:

self.word_counts[source].update({'date':posttime}, {"$inc" : words}, True)

Or pass upsert=True as a keyword argument:

self.word_counts[source].update({'date':posttime}, {"$inc" : words}, upsert=True)

Your mistake was likely caused by reading about update() in the MongoDB docs. The JavaScript version of update takes an object as its third argument containing optional parameters like upsert and multi. But since Python allows passing keyword arguments to a function (unlike JavaScript which only has positional arguments), this is unnecessary and PyMongo takes these options as optional function parameters instead.

According to http://api.mongodb.org/python/2.3/api/pymongo/collection.html#pymongo.collection.Collection.update you should indeed pass upsert as a keyword rather than just True, that is

self.word_counts[source].update({'date':posttime},{"$inc" : words},**{'upsert':True})

Or

self.word_counts[source].update({'date':posttime},{"$inc" : words},upsert=True)

is a better approach than just passing True as if you ever wish to pass other kwargs such as safe or multi code might break if order of args is not kept.

upsert should be passed as either positional parameter, like so

self.word_counts[source].update(
    {'date':posttime},
    {"$inc" : words},
    True)

or as a keyword argument, like so

self.word_counts[source].update(
    {'date':posttime},
    {"$inc" : words},
    upsert=True)