mongoc_collection_read_command_with_opts()¶

Synopsis¶

bool
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 concern is applied from opts or else from collection. Collation is applied from opts (see example for the “distinct” command with opts). Read preferences are applied from read_prefs or else from collection. No write concern is applied.

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

Parameters¶

collection: A mongoc_collection_t.
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: Construct a mongoc_client_session_t with mongoc_client_start_session() and use mongoc_client_session_append() to add the session to opts. See the example code for mongoc_client_session_t.
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 value.

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

Errors¶

Errors are propagated via the error parameter.

Returns¶

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

Example¶

See the example code for mongoc_client_read_command_with_opts().