mongoc_client_command - Man Page

mongoc_cursor_t *
mongoc_client_command (mongoc_client_t *client,
                       const char *db_name,
                       mongoc_query_flags_t flags,
                       uint32_t skip,
                       uint32_t limit,
                       uint32_t batch_size,
                       const bson_t *query,
                       const bson_t *fields,
                       const mongoc_read_prefs_t *read_prefs);

This function is not considered a retryable read operation.

This function creates a cursor which will execute the command when mongoc_cursor_next() is called on it. The client's read preference, read concern, and write concern are not applied to the command, and mongoc_cursor_next() will not check the server response for a write concern error or write concern timeout.

If mongoc_cursor_next() returns false, then retrieve error details with mongoc_cursor_error() or mongoc_cursor_error_document().

• client: A mongoc_client_t.
• db_name: The name of the database to run the command on.
• flags: Unused.
• skip: Unused.
• limit: Unused.
• batch_size: Unused.
• query: A bson_t containing the command specification.
• fields: Unused.
• read_prefs: An optional mongoc_read_prefs_t. Otherwise, the command uses mode MONGOC_READ_PRIMARY.

mongoc_client_command() is deprecated.

The following example uses mongoc_client_command():

Before

const bson_t *reply;
bson_t *cmd = BCON_NEW ("find", "foo", "filter", "{", "}");
mongoc_cursor_t *cursor = mongoc_client_command (client,
                                                 "db",
                                                 MONGOC_QUERY_NONE /* unused */,
                                                 0 /* unused */,
                                                 0 /* unused */,
                                                 0 /* unused */,
                                                 cmd,
                                                 NULL /* unused */,
                                                 NULL /* read prefs */);
// Expect cursor to return exactly one document for the command reply.
EXPECT (mongoc_cursor_next (cursor, &reply));

bson_error_t error;
if (mongoc_cursor_error (cursor, &error)) {
   FAIL ("Expected no error, got: %s\n", error.message);
}

// Expect successful reply to contain "ok": 1
bson_iter_t iter;
EXPECT (bson_iter_init_find (&iter, reply, "ok") && bson_iter_as_int64 (&iter) == 1);

// Expect cursor to return no other documents.
EXPECT (!mongoc_cursor_next (cursor, &reply));
mongoc_cursor_destroy (cursor);
bson_destroy (cmd);

The above code block may be rewritten to use mongoc_client_command_simple() instead, as shown below:

After

bson_t reply;
bson_error_t error;
bson_t *cmd = BCON_NEW ("find", "foo", "filter", "{", "}");
if (!mongoc_client_command_simple (client, "db", cmd, NULL /* read prefs */, &reply, &error)) {
   FAIL ("Expected no error, got: %s\n", error.message);
}

// Expect successful reply to contain "ok": 1
bson_iter_t iter;
EXPECT (bson_iter_init_find (&iter, &reply, "ok") && bson_iter_as_int64 (&iter) == 1);

bson_destroy (&reply);
bson_destroy (cmd);

A mongoc_cursor_t.

The cursor should be freed with mongoc_cursor_destroy().

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