New C++ Mongo driver: how to see type and how to get string value

问题

I've got two questions that I cannot find an answer for in the tutorial.

I get a document and then an element from the doc like this:

        bsoncxx::document::element e = doc["id"];

        if (!e || e.type() != bsoncxx::type::k_int32) return ERROR;
        int id = e.get_int32();

Is there a way to get a string value for the type, for debugging purposes? Like:

        std::cout << e.type() << std::endl;

(which doesn't work)

The second question is how to convert the utf8 type value into a std::string. This doesn't work:

        e = doc["name"];
        if (!e || e.type() != bsoncxx::type::k_utf8) return ERROR;
        string name = e.get_utf8().value;

Any tips?

回答1:

Printing Type as string (LIGNE 67)

#include <bsoncxx/types.hpp>

std::string bsoncxx::to_string(bsoncxx::type rhs);`

element to std::string

stdx::string_view view = e.get_utf8().value;
string name = view.to_string();

stdx::string_view
std::string_view

回答2:

#include <bsoncxx/types.hpp>

std::cout << bsoncxx::to_string(bsoncxx::types::b_utf8::type_id);

result: "utf8"

And these are type of bsoncxx

namespace types {
struct b_eod;
struct b_double;
struct b_utf8;
struct b_document;
struct b_array;
struct b_binary;
struct b_undefined;
struct b_oid;
struct b_bool;
struct b_date;
struct b_null;
struct b_regex;
struct b_dbpointer;
struct b_code;
struct b_symbol;
struct b_codewscope;
struct b_int32;
struct b_timestamp;
struct b_int64;
struct b_minkey;
struct b_maxkey;
class value;
}  // namespace types

来源：https://stackoverflow.com/questions/35920013/new-c-mongo-driver-how-to-see-type-and-how-to-get-string-value

标签

c++

mongodb

mongo-cxx-driver