PARAMETERS

/*
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;
}