In python/pymongo, creating GeoSpatial index is quite trivial:
db.collection.create_index([("loc", GEO2D)], min=-100, max=100)
After that I can insert data using "loc" field.
But in C++/mongocxx, after referring mongocxx document (http://mongodb.github.io/mongo-cxx-driver/mongocxx-v3/tutorial/) and GeoSpatial docement, I still cannot figure out how to do this.
Could anyone kindly show me how to deal with Geospatial index in C++? Thanks in advance.
You can create a GeoSpatial index with the C++ driver in a similar way to the Python driver; the main difference is that instead of passing the minimum and maximum as direct arguments to create_index, they're instead set in an options::index object which is then passed to create_index. Here's a short program that creates the index you described above using the C++ driver:
#include <bsoncxx/builder/basic/document.hpp>
#include <bsoncxx/builder/basic/kvp.hpp>
#include <mongocxx/client.hpp>
#include <mongocxx/instance.hpp>
#include <mongocxx/options/index.hpp>
#include <mongocxx/uri.hpp>
using namespace mongocxx;
using bsoncxx::builder::basic::kvp;
int main() {
instance inst{};
client conn{uri{}};
auto coll = conn["db_name"]["coll_name"];
bsoncxx::builder::basic::document index_doc;
index_doc.append(kvp("loc", "2d"));
coll.create_index(
index_doc.extract(),
options::index{}
.twod_location_min(-100).twod_location_max(100));
}
