C++驱动库

Additional Notes¶

• The Building documentation covers compiling the entire database, but some of the notes there may be helpful for compiling client applications too.
• There is a pure C driver for MongoDB, but for true C++ apps we recommend using the C++ driver.

C++ BSON Library¶

The MongoDB C++ driver library includes a bson package that implements the BSON specification (see http://www.bsonspec.org). This library can be used standalone for object serialization and deserialization even when one is not using MongoDB at all.

Include bson/bson.h or db/jsobj.h in your application (not both). bson.h is new and may not work in some situations, was is good for light header-only usage of BSON (see the bsondemo.cpp example).

Key classes:

• mongo::BSONObj (aka bson::bo): a BSON object
• mongo::BSONElement (bson::be): a single element in a BSON object. This is a key and a value.
• mongo::BSONObjBuilder (bson::bob): used to make BSON objects
• mongo::BSONObjIterator (bson::bo::iterator): used to enumerate BSON objects

See BSON examples in the Getting Started guide

using namespace bson;

// from bsonelement.h
namespace bson {
    typedef mongo::BSONElement be;
    typedef mongo::BSONObj bo;
    typedef mongo::BSONObjBuilder bob;
}

C++ DBClientConnection¶

The C++ driver includes several classes for managing collections under the parent class DBClientInterface.

DBClientConnection is our normal connection class for a connection to a single MongoDB database server (or shard manager). Other classes exist for connecting to a replica set.

See http://api.mongodb.org/cplusplus for details on each of the above classes.

C++ getLastError¶

• string mongo::DBClientWithCommands::getLastError(); Get error result from the last operation on this connection. Empty string if no error.
• BSONObj DBClientWithCommands::getLastErrorDetailed(); Get the full last error object. See the getLastError Command page for details.

For an example, see client/simple_client_demo.cpp.

Also see getLastError Command.