bool
mongoc_client_read_command_with_opts (mongoc_client_t *client,


                                      const char *db_name,


                                      const bson_t *command,


                                      const mongoc_read_prefs_t *read_prefs,


                                      const bson_t *opts,


                                      bson_t *reply,


                                      bson_error_t *error);

/*
Demonstrates how to prepare options for mongoc_client_read_command_with_opts and
mongoc_client_write_command_with_opts. First it calls "cloneCollectionAsCapped"
command with "writeConcern" option, then "distinct" command with "collation" and
"readConcern" options,
Start a MongoDB 3.4 replica set with --enableMajorityReadConcern and insert two
documents:
$ mongo
MongoDB Enterprise replset:PRIMARY> db.my_collection.insert({x: 1, y: "One"})
WriteResult({ "nInserted" : 1 })
MongoDB Enterprise replset:PRIMARY> db.my_collection.insert({x: 2, y: "Two"})
WriteResult({ "nInserted" : 1 })
Build and run the example:
gcc example-command-with-opts.c -o example-command-with-opts $(pkg-config
--cflags --libs libmongoc-1.0)
./example-command-with-opts [CONNECTION_STRING]
cloneCollectionAsCapped: { "ok" : 1 }
distinct: { "values" : [ 1, 2 ], "ok" : 1 }
*/
#include <mongoc/mongoc.h>
#include <stdio.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{


   mongoc_client_t *client;


   const char *uri_string = "mongodb://127.0.0.1/?appname=client-example";


   mongoc_uri_t *uri;


   bson_t *cmd;


   bson_t *opts;


   mongoc_write_concern_t *write_concern;


   mongoc_read_prefs_t *read_prefs;


   mongoc_read_concern_t *read_concern;


   bson_t reply;


   bson_error_t error;


   char *json;


   mongoc_init();


   if (argc > 1) {


      uri_string = argv[1];


   }


   uri = mongoc_uri_new_with_error(uri_string, &error);


   if (!uri) {


      fprintf(stderr,


              "failed to parse URI: %s\n"


              "error message:       %s\n",


              uri_string,


              error.message);


      return EXIT_FAILURE;


   }


   client = mongoc_client_new_from_uri(uri);


   if (!client) {


      return EXIT_FAILURE;


   }


   mongoc_client_set_error_api(client, 2);


   cmd = BCON_NEW("cloneCollectionAsCapped",


                  BCON_UTF8("my_collection"),


                  "toCollection",


                  BCON_UTF8("my_capped_collection"),


                  "size",


                  BCON_INT64(1024 * 1024));


   /* include write concern "majority" in command options */


   write_concern = mongoc_write_concern_new();


   mongoc_write_concern_set_wmajority(write_concern, 10000 /* wtimeoutMS */);


   opts = bson_new();


   mongoc_write_concern_append(write_concern, opts);


   if (mongoc_client_write_command_with_opts(client, "test", cmd, opts, &reply, &error)) {


      json = bson_as_canonical_extended_json(&reply, NULL);


      printf("cloneCollectionAsCapped: %s\n", json);


      bson_free(json);


   } else {


      fprintf(stderr, "cloneCollectionAsCapped: %s\n", error.message);


   }


   bson_free(cmd);


   bson_free(opts);


   /* distinct values of "x" in "my_collection" where "y" sorts after "one" */


   cmd = BCON_NEW("distinct",


                  BCON_UTF8("my_collection"),


                  "key",


                  BCON_UTF8("x"),


                  "query",


                  "{",


                  "y",


                  "{",


                  "$gt",


                  BCON_UTF8("one"),


                  "}",


                  "}");


   read_prefs = mongoc_read_prefs_new(MONGOC_READ_SECONDARY);


   /* "One" normally sorts before "one"; make "One" sort after "one" */


   opts = BCON_NEW("collation", "{", "locale", BCON_UTF8("en_US"), "caseFirst", BCON_UTF8("lower"), "}");


   /* add a read concern to "opts" */


   read_concern = mongoc_read_concern_new();


   mongoc_read_concern_set_level(read_concern, MONGOC_READ_CONCERN_LEVEL_MAJORITY);


   mongoc_read_concern_append(read_concern, opts);


   if (mongoc_client_read_command_with_opts(client, "test", cmd, read_prefs, opts, &reply, &error)) {


      json = bson_as_canonical_extended_json(&reply, NULL);


      printf("distinct: %s\n", json);


      bson_free(json);


   } else {


      fprintf(stderr, "distinct: %s\n", error.message);


   }


   bson_destroy(cmd);


   bson_destroy(opts);


   bson_destroy(&reply);


   mongoc_read_prefs_destroy(read_prefs);


   mongoc_read_concern_destroy(read_concern);


   mongoc_write_concern_destroy(write_concern);


   mongoc_uri_destroy(uri);


   mongoc_client_destroy(client);


   mongoc_cleanup();


   return EXIT_SUCCESS;
}