mongoc_collection_read_command_with_opts (mongoc_collection_t *collection,
                                          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_collection_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_prefs opts opts
Transaction Transaction  

See the example for transactions and for the “distinct” command with opts.

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


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

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.


See the example code for mongoc_client_read_command_with_opts().