Provided by: libmongoc-doc_1.15.0-1_all bug


       mongoc_client_read_command_with_opts - mongoc_client_read_command_with_opts()


          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);

       Execute  a  command  on the server, applying logic that is specific to commands that read,
       and taking the MongoDB server version into account. To send a raw command  to  the  server
       without any of this logic, use mongoc_client_command_simple.

       Use this function for commands that read such as "count" or "distinct".

       Read  preferences,  read concern, and collation can be overridden by various sources. In a
       transaction, read concern and write concern are prohibited in opts and the read preference
       must  be  primary or NULL. The highest-priority sources for these options are listed first
       in the following table. No write concern is applied.

                             │Read Preferences │ Read Concern │ Collation │
                             │read_prefsoptsopts      │
                             │Transaction      │ Transaction  │           │
                             │client           │              │           │

       See the example for transactions and for the "distinct" command with opts.

       reply is always initialized, and must be freed with bson_destroy().


       · client: A mongoc_client_t.

       · db_name: The name of the database to run the command on.

       · command: A bson_t containing the command specification.

       · read_prefs: An optional mongoc_read_prefs_t.

       · opts: A bson_t containing additional options.

       · reply: A location for the resulting document.

       · error: An optional location for a bson_error_t or NULL.

       opts may be NULL or a BSON document with additional command options:

       · readConcern: Construct a mongoc_read_concern_t and use mongoc_read_concern_append to add
         the read concern to opts. See the example code for mongoc_client_read_command_with_opts.
         Read concern requires MongoDB 3.2 or later, otherwise an error is returned.

       · sessionId: First, construct a mongoc_client_session_t with  mongoc_client_start_session.
         You  can  begin  a  transaction with mongoc_client_session_start_transaction, optionally
         with a mongoc_transaction_opt_t that overrides the options inherited  from  client,  and
         use  mongoc_client_session_append  to  add the session to opts. See the example code for

       · collation: Configure textual comparisons. See Setting Collation Order, and  the  MongoDB
         Manual  entry  on Collation. Collation requires MongoDB 3.2 or later, otherwise an error
         is returned.

       · serverId: To target a specific server, include an int32 "serverId" field. Obtain the  id
         by  calling mongoc_client_select_server, then mongoc_server_description_id on its return

       Consult the MongoDB Manual entry on Database Commands for each command's arguments.


       Errors are propagated via the error parameter.


       Returns true if successful. Returns false and sets error if there are invalid arguments or
       a server or network 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

          $ 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>

          main (int argc, char *argv[])
             mongoc_client_t *client;
             const char *uri_string = "mongodb://";
             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",
                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"),
                             BCON_UTF8 ("my_capped_collection"),
                             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"),
                             BCON_UTF8 ("x"),
                             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",
                              BCON_UTF8 ("en_US"),
                              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_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;


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