From c9182b959b5a11cef0b42795ade1d4814011943e Mon Sep 17 00:00:00 2001
From: "Begerad, Stefan" <dialog@swingbe.de>
Date: Mon, 31 Jul 2023 19:18:39 +0200
Subject: [PATCH] feat(api-ulfius): add routes bike-ride, taxi, ticket-office,
 ticket-machine

---
 api-ulfius/src/main.c | 565 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 562 insertions(+), 3 deletions(-)

diff --git a/api-ulfius/src/main.c b/api-ulfius/src/main.c
index e33b10c..d19520a 100644
--- a/api-ulfius/src/main.c
+++ b/api-ulfius/src/main.c
@@ -23,7 +23,11 @@
 #include <pthread.h>
 
 #define ROUTE_HELLO "/hello"
+#define ROUTE_BIKE_RIDE "/bike-ride"
 #define ROUTE_BUS_STOP "/bus-stop"
+#define ROUTE_TAXI "/taxi"
+#define ROUTE_TICKET_OFFICE "/ticket-office"
+#define ROUTE_TICKET_MACHINE "/ticket-machine"
 #define ROUTE_TRAIN_STATION "/train-station"
 #define ROUTE_PARK_RIDE "/park-ride"
 
@@ -35,9 +39,24 @@ pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
 int callback_get_hello (const struct _u_request * request, struct _u_response * response, void * user_data);
 
 int callback_default (const struct _u_request * request, struct _u_response * response, void * user_data);
+
 int callback_get_bus_stop_count (const struct _u_request * request, struct _u_response * response, void * user_data);
+
+int callback_get_bike_ride_count (const struct _u_request * request, struct _u_response * response, void * user_data);
+int callback_get_bike_ride_info (const struct _u_request * request, struct _u_response * response, void * user_data);
+
+int callback_get_taxi_count (const struct _u_request * request, struct _u_response * response, void * user_data);
+int callback_get_taxi_info (const struct _u_request * request, struct _u_response * response, void * user_data);
+
+int callback_get_ticket_office_count (const struct _u_request * request, struct _u_response * response, void * user_data);
+int callback_get_ticket_office_info (const struct _u_request * request, struct _u_response * response, void * user_data);
+
+int callback_get_ticket_machine_count (const struct _u_request * request, struct _u_response * response, void * user_data);
+int callback_get_ticket_machine_info (const struct _u_request * request, struct _u_response * response, void * user_data);
+
 int callback_get_train_station_count (const struct _u_request * request, struct _u_response * response, void * user_data);
 int callback_get_train_station_info (const struct _u_request * request, struct _u_response * response, void * user_data);
+
 int callback_get_park_ride_count (const struct _u_request * request, struct _u_response * response, void * user_data);
 int callback_get_park_ride_info (const struct _u_request * request, struct _u_response * response, void * user_data);
 
@@ -176,9 +195,23 @@ int main(int argc, char *argv[]) {
   ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_HELLO, NULL, 0, &callback_get_hello, NULL);
 
   //user_data: pass pq connection information to callback
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_BIKE_RIDE, "/count", 0, &callback_get_bike_ride_count, (void *)conn);
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_BIKE_RIDE, "/info", 0, &callback_get_bike_ride_info, (void *)conn);
+
   ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_BUS_STOP, "/count", 0, &callback_get_bus_stop_count, (void *)conn);
+
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TAXI, "/count", 0, &callback_get_taxi_count, (void *)conn);
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TAXI, "/info", 0, &callback_get_taxi_info, (void *)conn);
+
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TICKET_OFFICE, "/count", 0, &callback_get_ticket_office_count, (void *)conn);
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TICKET_OFFICE, "/info", 0, &callback_get_ticket_office_info, (void *)conn);
+
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TICKET_MACHINE, "/count", 0, &callback_get_ticket_machine_count, (void *)conn);
+  ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TICKET_MACHINE, "/info", 0, &callback_get_ticket_machine_info, (void *)conn);
+
   ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TRAIN_STATION, "/count", 0, &callback_get_train_station_count, (void *)conn);
   ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_TRAIN_STATION, "/info", 0, &callback_get_train_station_info, (void *)conn);
+
   ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_PARK_RIDE, "/count", 0, &callback_get_park_ride_count, (void *)conn);
   ulfius_add_endpoint_by_val(&instance, "GET", ROUTE_PARK_RIDE, "/info", 0, &callback_get_park_ride_info, (void *)conn);
 
@@ -302,7 +335,6 @@ int callback_get_bus_stop_count (const struct _u_request * request, struct _u_re
 }
 
 /**
- * Callback function to reply number of all train stations
  */
 int callback_get_train_station_count (const struct _u_request * request, struct _u_response * response, void * user_data) {
   /*declarations*/
@@ -369,7 +401,6 @@ int callback_get_train_station_count (const struct _u_request * request, struct
 }
 
 /**
- * Callback function to reply number of all train stations
  */
 int callback_get_park_ride_count (const struct _u_request * request, struct _u_response * response, void * user_data) {
   /*declarations*/
@@ -503,7 +534,6 @@ int callback_get_train_station_info (const struct _u_request * request, struct _
 }
 
 /**
- * Callback function to reply all train stations
  */
 int callback_get_park_ride_info (const struct _u_request * request, struct _u_response * response, void * user_data) {
   /*declarations*/
@@ -568,3 +598,532 @@ int callback_get_park_ride_info (const struct _u_request * request, struct _u_re
   printf("callback_get_park_ride_info() Done.\n");
   return U_CALLBACK_CONTINUE;
 }
+
+/**
+ */
+int callback_get_bike_ride_info (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_bike_ride_info() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT osm_id AS id, bike_ride AS tag, name, st_x AS lon, st_y AS lat FROM rvb.tbl_bike_ride;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_bike_ride_info() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_bike_ride_info() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_bike_ride_info() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_bike_ride_info() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_bike_ride_info() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+
+/**
+ */
+int callback_get_bike_ride_count (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_bike_ride_count() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT count(DISTINCT osm_id) FROM rvb.tbl_bike_ride;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_bike_ride_count() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_bike_ride_count() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_bike_ride_count() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_bike_ride_count() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_bike_ride_count() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+
+/**
+ */
+int callback_get_taxi_info (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_taxi_info() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT osm_id AS id, amenity AS tag, name, st_x AS lon, st_y AS lat FROM rvb.tbl_taxi;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_taxi_info() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_taxi_info() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_taxi_info() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_taxi_info() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_taxi_info() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+
+/**
+ */
+int callback_get_ticket_office_count (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_ticket_office_count() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT count(DISTINCT osm_id) FROM rvb.tbl_shop_ticket;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_ticket_office_count() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_ticket_office_count() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_ticket_office_count() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_ticket_office_count() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_ticket_office_count() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+
+/**
+ */
+int callback_get_ticket_machine_count (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_ticket_machine_count() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT count(DISTINCT osm_id) FROM rvb.tbl_vending_machine;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_ticket_machine_count() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_ticket_machine_count() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_ticket_machine_count() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_ticket_machine_count() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_ticket_machine_count() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+
+/**
+ */
+int callback_get_ticket_office_info (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_ticket_office_info() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT osm_id AS id, shop AS tag, name, st_x AS lon, st_y AS lat FROM rvb.tbl_shop_ticket;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_ticket_office_info() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_ticket_office_info() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_ticket_office_info() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_ticket_office_info() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_ticket_office_info() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+
+/**
+ */
+int callback_get_ticket_machine_info (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_ticket_machine_info() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT osm_id AS id, amenity AS tag, name, st_x AS lon, st_y AS lat FROM rvb.tbl_vending_machine;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_ticket_machine_info() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_ticket_machine_info() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_ticket_machine_info() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_ticket_machine_info() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_ticket_machine_info() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+
+/**
+ */
+int callback_get_taxi_count (const struct _u_request * request, struct _u_response * response, void * user_data) {
+  /*declarations*/
+  PGconn *conn;
+  char *prepStatement;
+  PGresult *pqRes;
+  int nbRecords,nbFields;
+  json_t *arrayRecords, *arrayFields,  *stringField;
+
+  printf("callback_get_taxi_count() Started...\n");
+  conn = (PGconn *)user_data;
+
+  /*define prepared statement*/
+  prepStatement = "SELECT count(DISTINCT osm_id) FROM rvb.tbl_taxi;";
+
+  //lock PGconn mutex
+  pthread_mutex_lock(&mutex);
+
+  /*create prepared statement*/
+  pqRes = PQexecParams(conn, prepStatement, 0, NULL, NULL, NULL, NULL, 0);
+
+  //unlock PGconn mutex
+  pthread_mutex_unlock(&mutex);
+
+  if (PQresultStatus(pqRes) != PGRES_TUPLES_OK) {
+    printf("callback_get_taxi_count() No data retrieved\n");
+    /*clean up result*/
+    PQclear(pqRes);
+    //TODO Why this casting?
+    (void)(request);
+    (void)(user_data);
+    ulfius_set_string_body_response(response, 500, "This is the /entities route: Dba error!");
+    printf("callback_get_taxi_count() Done.\n");
+    return U_CALLBACK_CONTINUE;
+  }
+
+  /*evaluate result*/
+  nbRecords = PQntuples(pqRes);
+  //printf("callback_get_taxi_count() nbRecords: %d\n",nbRecords);
+  nbFields = PQnfields(pqRes);
+  //printf("callback_get_taxi_count() nbFields: %d\n",nbFields);
+  arrayRecords=json_array();
+  for(int i=0;i<nbRecords;i++){
+    arrayFields=json_array();
+    for(int j=0;j<nbFields;j++){
+      stringField = json_string(PQgetvalue(pqRes,i,j));
+      json_array_append(arrayFields, stringField);
+      json_decref(stringField);
+    }
+    json_array_append(arrayRecords, arrayFields);
+    json_decref(arrayFields);
+  }
+  /*clean up result*/
+  PQclear(pqRes);
+  /*set response body*/
+  ulfius_set_json_body_response(response, 200, arrayRecords);
+  /*clean up JSON*/
+  json_decref(arrayRecords);
+  //TODO Why this casting?
+  (void)(request);
+  (void)(user_data);
+  printf("callback_get_taxi_count() Done.\n");
+  return U_CALLBACK_CONTINUE;
+}
+