C++ BSON 帮助函数

This is a non-exhaustive list of helper functions for use in the C++ stream syntax. An exhaustive list is here: bsonmisc.h

Typical example of stream syntax:

BSONObj p = BSON( "name" << "Joe" << "age" << 33 );

• GENOID

  The server will add an _id automatically if it is not included explicitly.

  BSONObj p = BSON( GENOID << "name" << "Joe" << "age" << 33 );
  // result is: { _id : ..., name : "Joe", age : 33 }
  

• LT, GT, LTE, GTE, NE

  less than, greater than, etc.

  BSONObj p = BSON( "age" << GT << 21 );
  // result is:  { age : { $gt : 21 } }
  

• DATENOW

  Translates to current date

  BSONObj p = BSON( "created" << DATENOW );
  // result is: { created : "2009-10-09 11:41:42" }
  

• MINKEY, MAXKEY

  BSONObj p = BSON( "a" << MINKEY);
  // result is: { "a" : { "$minKey" : 1 } }
  

  OR

  OR(BSON("x" << GT << 7), BSON("y" << LT << 6))
  // result is: {$or: [{x: {$gt: 7}}, {y: {$lt: 6}}]}
  

• BSONNULL

  Translates to null value (will appear in MongoDB 2.1)

  BSONObj p = BSON( "name" << "Methuselah" << "age" << BSONNULL );
  // result is: { name : "Methuselah", age : null }