bson_append_array man page
bson_append_array — bson_append_array()
bool bson_append_array (bson_t *bson, const char *key, int key_length, const bson_t *array);
bson: A bson_t.
key: An ASCII C string containing the name of the field.
key_length: The length of key in bytes, or -1 to determine the length with strlen().
array: A bson_t.
The bson_append_array() function shall append child to bson using the specified key. The type of the field will be an array, but it is the responsibility of the caller to ensure that the keys of child are properly formatted with string keys such as "0", "1", "2" and so forth.
true if the operation was applied successfully, otherwise false and bson should be discarded.
2017, MongoDB, Inc