mongo C++ 驱动程序中的空 BSON_ARRAY()
Empty BSON_ARRAY() in mongo C++ driver
以下适用于 mongo C++ BSON() 和 BSON_ARRAY() 宏:
BSONObj cr4 = BSON("providingApplication" << "http://cpr2.com" <<
"entities" << BSON_ARRAY(
BSON("id" << "E1" << "type" << "T")
) <<
"attrs" << BSON_ARRAY(
BSON("name" << "A5" << "type" << "T" << "isDomain" << "false")
)
);
但是,如果我尝试对 attrs
字段使用空的 BSON 数组
BSONObj cr4 = BSON("providingApplication" << "http://cpr2.com" <<
"entities" << BSON_ARRAY(
BSON("id" << "E1" << "type" << "T")
) <<
"attrs" << BSON_ARRAY()
);
它不起作用(甚至无法编译)。
关于如何在 mongo c++ 驱动程序中使用 BSON 宏生成空数组的提示,请问?
看来BSONArray()
解决了问题:
BSONObj cr4 = BSON("providingApplication" << "http://cpr2.com" <<
"entities" << BSON_ARRAY(
BSON("id" << "E1" << "type" << "T")
) <<
"attrs" << BSONArray()
);
感谢 Öö Tiib 的提示!
以下适用于 mongo C++ BSON() 和 BSON_ARRAY() 宏:
BSONObj cr4 = BSON("providingApplication" << "http://cpr2.com" <<
"entities" << BSON_ARRAY(
BSON("id" << "E1" << "type" << "T")
) <<
"attrs" << BSON_ARRAY(
BSON("name" << "A5" << "type" << "T" << "isDomain" << "false")
)
);
但是,如果我尝试对 attrs
字段使用空的 BSON 数组
BSONObj cr4 = BSON("providingApplication" << "http://cpr2.com" <<
"entities" << BSON_ARRAY(
BSON("id" << "E1" << "type" << "T")
) <<
"attrs" << BSON_ARRAY()
);
它不起作用(甚至无法编译)。
关于如何在 mongo c++ 驱动程序中使用 BSON 宏生成空数组的提示,请问?
看来BSONArray()
解决了问题:
BSONObj cr4 = BSON("providingApplication" << "http://cpr2.com" <<
"entities" << BSON_ARRAY(
BSON("id" << "E1" << "type" << "T")
) <<
"attrs" << BSONArray()
);
感谢 Öö Tiib 的提示!