write_objects_to_json.cpp

/**
 *  This example shows how to work with json stored objects
 *  RCDB uses json library
 *  https://github.com/nlohmann/json
 */
#include <string>
#include <iostream>

#include "RCDB/WritingConnection.h"
#include "RCDB/StringUtils.h"
#include <tao/json.hpp>

using namespace tao;

int main(int argc, char *argv[]) {
    using namespace std;

    // Get a connection string from arguments
    if (argc != 2) {
        cout << "This example writes objects as j for a specified run" << endl;
        cout<<"rcnd --create json_cnd --type j --description \"JSON serialized values\""<<endl;
        cout << "usage: " << argv[0] << " <connection_string>" << endl;
        cout << "exmpl: " << argv[0] << " mysql://rcdb@localhost/rcdb" << endl;
        cout << "exmpl: " << argv[0] << " mysql://rcdb:password@clondb1/rcdb" << endl;
        return 1;
    }
    string connection_str(argv[1]);

    // Create DB connection
    rcdb::WritingConnection connection(connection_str);

    struct tm start_time;

    start_time.tm_year = 2016 - 1900;
    start_time.tm_mon = 1;
    start_time.tm_mday = 4;
    start_time.tm_hour = 02;
    start_time.tm_min = 30;
    start_time.tm_sec = 38;
    start_time.tm_isdst = 0;

    struct tm end_time;

    end_time.tm_year = 2016 - 1900;
    end_time.tm_mon = 1;
    end_time.tm_mday = 4;
    end_time.tm_hour = 04;
    end_time.tm_min = 25;
    end_time.tm_sec = 10;
    end_time.tm_isdst = 0;

    connection.AddRun(999);
    connection.AddRunStartTime(999, start_time);
    connection.AddRunEndTime(999, end_time);


/*
id      name           value_type      created              description
1       event_count       int     2017-03-15 14:18:55     Number of events in run
2       events_rate       float   2017-03-15 14:18:55     Daq events rate
3       temperature       int     2017-03-15 14:18:55     Temperature of the Sun
4       beam_energy       float   2017-03-15 18:57:22     Beam Energy
5       test              float   2017-03-15 18:58:00     Beam test
6       beam_current      float   2017-03-15 19:02:10     Beam current
7       torus_scale       float   2017-03-15 19:02:10     Torus scale factor
8       daq_trigger       string  2017-03-15 19:02:10     Trigger file
9       target_position   float   2017-03-15 19:02:10     Target position
10      daq_comment       string  2017-03-15 19:02:10     DAQ comment
11      run_start_time    time    2017-04-21 10:28:49     Run start time
12      run_end_time      time    2017-04-21 10:29:02     Run end time
13      is_valid_run_end  bool    2017-04-21 10:48:35     True if a run has valid run-end record. False mean...
14      status            int     2017-05-17 13:30:34     Run Status
*/

    int32_t event_count = 12345;
    float events_rate = 98765.32;
    int32_t temperature = 77;
    float beam_energy = 6.095;
    float test = 1234567890.123;
    string daq_trigger = "trigger_file_name";
    string daq_comment = "this run is junk";
    std::vector<int> c_vector{1, 2, 3, 4};




    // P A R T   1 - w r i t i n g   a r r a y

    // You can create j a way, which looks very similar to the JSON itself)
    json::value j({
            {"event_count", event_count},
            {"events_rate", events_rate},
            {"temperature", temperature},
            {"beam_energy", beam_energy},
            {"daq_trigger", daq_trigger},
            {"test",        test},
            {"list",        {json::value::array({1, 0, true})} },
            {"object",      {{"currency", "USD"}, {"value", 42.99}} },
            {"start_time",  StringUtils::GetFormattedTime(start_time)}
        });

    // copy array to json
    auto c_vector_json = json::value::array({});
    for(auto& item: c_vector) c_vector_json.emplace_back(item);

    // + operator adds one json to another
    j += {{"c_vector", c_vector_json }};


    // or act as a dictionary
    // add a number that is stored as double (note the implicit conversion of j to an object)
    j["pi"] = 3.141;

    // Pretty formatted j
    cout << tao::json::to_string(j, 4) << endl;

    // compact formatted j
    cout << tao::json::to_string(j) << endl;

    // Add condition
    connection.AddCondition(999, "json_cnd", tao::json::to_string(j));


    // P A R T   2 - r e a d i n g   a r r a y

    auto cnd = connection.GetCondition(999, "json_cnd");
    auto data = tao::json::from_string(cnd->ToString());

    // iterate underlying map<name, value>
    auto &object = data.get_object();
    //for ( auto it= object.begin(); it != object.end(); ++it) {
        //std::cout << *it <<" "<< *it << std::endl;
    //}

    // range-based for
    for (auto& element : object) {
        std::cout << element.first << " " << element.first << std::endl;
    }


    int32_t ev_cnt = object["event_count"].get_unsigned();

    // explicit data conversion
    auto trigger = data["daq_trigger"].get_string();

    cout<<"event_count= "<<ev_cnt<<"   trigger= "<<trigger<<"   start_time="<<data["start_time"]<<endl;

    return 0;
}