Using Pymongo Update to perform an Insert and Update

Was working on a module that would iterate through a row list that came back from a query and attempt to insert or update the specific columns of the returned rows to a collection on Mongo. Originally I was planning to use count({"id":row[id]}) > 0 to check for the existence of the given record in Mongo, and then execute a insert of push as needed. However I stumbled the update method which is part of pymongos collection level operators that allows me to execute all three actions, check for existence, insert or push, with one call.

So my original code to insert or update was as shown below:
 #check if row exist
 if coll.count({"MemberId": row["idclient"]}) > 0:
 #Insert row into the Collection
 coll.insert(details) else:
 #update the existing row
 coll.push({"MemberId": str(row["idclient"])}, { $push: { "field1": str(row["field1"]), "field2": str(row["field2"])} })
 As observable from above the push call requires us to decompose the details dictionary object into its elements to update.
However with the push I can skip these three lines and execute the same operation with one call: coll.update(key, details, True)
 I have to set up what key to use and also have to set the upsert flag to be true, then an update() (upsert) operation is performed and any existing document with that "_id" is overwritten. Otherwise an insert() operation is performed.
 See below for the link on stack overflow that provided the motivation for this and the documentation on MongoDB.org that explain the workings of the update method.

http://stackoverflow.com/questions/2801008/mongodb-insert-if-not-exists

http://api.mongodb.org/python/current/api/pymongo/collection.html