How to convert string to BSON using MongoDB C++ driver?
Use the fromjson method found here:
http://api.mongodb.org/cplusplus/1.5.4/namespacemongo.html#a4f542be0d0f9bad2d8cb32c3436026c2
BSONObj mongo::fromjson ( const string & str ) Create a BSONObj from a JSON <http://www.json.org> string.In addition to the JSON extensions extensions described here http://mongodb.onconfluence.com/display/DOCS/Mongo+Extended+JSON, this function accepts certain unquoted field names and allows single quotes to optionally be used when specifying field names and string values instead of double quotes. JSON unicode escape sequences (of the form ) are converted to utf8.
Exceptions: MsgAssertionException if parsing fails. The message included with this assertion includes a rough indication of where parsing failed.