Repository: gabime/spdlog
File: include/spdlog/sinks/mongo_sink.h (C/C++)

Code before:
#include <bsoncxx/view_or_value.hpp>

#include <mongocxx/client.hpp>
#include <mongocxx/exception/logic_error.hpp>
#include <mongocxx/instance.hpp>
#include <mongocxx/uri.hpp>

namespace spdlog {
namespace sinks {
template<typename Mutex>
class mongo_sink : public base_sink<Mutex>
{
public:
    mongo_sink(const std::string &db_name, const std::string &collection_name, const std::string &uri = "mongodb://localhost:27017")
        : mongo_sink(std::make_shared<mongocxx::instance>(), db_name, collection_name, uri) {}

    mongo_sink(const std::shared_ptr<mongocxx::instance> &instance, const std::string &db_name, const std::string &collection_name, const std::string &uri = "mongodb://localhost:27017")
        : instance_(instance)
        , db_name_(db_name)
        , coll_name_(collection_name)
    {
        try
        {
            client_ = spdlog::details::make_unique<mongocxx::client>(mongocxx::uri{uri});
        }
        catch (const std::exception&)
        {
            throw spdlog_ex("Error opening database");
        }
    }

    ~mongo_sink()
    {
        flush_();
    }

protected:
    void sink_it_(const details::log_msg &msg) override
    {
        using bsoncxx::builder::stream::document;
        using bsoncxx::builder::stream::finalize;

        if (client_ != nullptr)
        {
            auto doc = document{} << "timestamp" << bsoncxx::types::b_date(msg.time)
                                  << "level" << level::to_string_view(msg.level).data() << "level_num" << msg.level
                                  << "message" << std::string(msg.payload.begin(), msg.payload.end()) << "logger_name"
                                  << std::string(msg.logger_name.begin(), msg.logger_name.end()) << "thread_id"
                                  << static_cast<int>(msg.thread_id) << finalize;
            client_->database(db_name_).collection(coll_name_).insert_one(doc.view());
        }

Review comment (refactor):
How about adding a catch clause to catch the [mongo exception](http://mongocxx.org/api/current/classmongocxx_1_1operation__exception.html) to extract its what() string and add to the spdlog_ex message as well ?  

Code after:
#include <bsoncxx/view_or_value.hpp>

#include <mongocxx/client.hpp>
#include <mongocxx/instance.hpp>
#include <mongocxx/uri.hpp>

namespace spdlog {
namespace sinks {
template<typename Mutex>
class mongo_sink : public base_sink<Mutex>
{
public:
    mongo_sink(const std::string &db_name, const std::string &collection_name, const std::string &uri = "mongodb://localhost:27017")
    try : mongo_sink(std::make_shared<mongocxx::instance>(), db_name, collection_name, uri)
    {}
    catch (const std::exception &e)
    {
        throw_spdlog_ex(fmt_lib::format("Error opening database: {}", e.what()));
    }

    mongo_sink(std::shared_ptr<mongocxx::instance> instance, const std::string &db_name, const std::string &collection_name,
        const std::string &uri = "mongodb://localhost:27017")
        : instance_(std::move(instance))
        , db_name_(db_name)
        , coll_name_(collection_name)
    {
        try
        {
            client_ = spdlog::details::make_unique<mongocxx::client>(mongocxx::uri{uri});
        }
        catch (const std::exception &e)
        {
            throw_spdlog_ex(fmt_lib::format("Error opening database: {}", e.what()));
        }
    }

    ~mongo_sink()
    {
        flush_();
    }

protected:
    void sink_it_(const details::log_msg &msg) override
    {
        using bsoncxx::builder::stream::document;
        using bsoncxx::builder::stream::finalize;

        if (client_ != nullptr)
        {
            auto doc = document{} << "timestamp" << bsoncxx::types::b_date(msg.time) << "level" << level::to_string_view(msg.level).data()
                                  << "level_num" << msg.level << "message" << std::string(msg.payload.begin(), msg.payload.end())