Append an item into an array inside a struct - solidity

Question

Working on solidity 8.12, I have two structs, namely singer and event, two arrays one for singers and another for events. I want to write down a function that creates an event, specifying the singer id, and automatically append the event id into the array of events attended by the singer:
struct Singer {
uint id;
uint[] events_ids; // THIS IS WHAT I WANT TO UPDATE WITH THE NEW EVENT ID
}
struct Event {
uint id;
uint singer_id;
}
singer[] public SingerList;
event[] public EventList;
uint public n_singers;
uint public n_events;
function CreateEvent(uint singer_id) external {
if (singer_id > n_singers) { // singer id greater than the number of current singers.
revert SingerIdError(singer_id);
}
else if (singer_id == n_singers){ // the singer does not exist yet! Create it!
n_singers ++;
--------> SingerList.push(Singer(singer_id))); // HOW TO APPEND THE EVENT ID TO THE LIST OF EVENTS IN SINGER STRUCT?
EventList.push(Event(n_events, singer_id));
}
else { // the pilot already exists
Singer storage _singer = SingerList[singer_id];
_singer.event_ids.push(n_events);
EventList.push(Event(n_events, n_events));
}
n_events ++;
}```

Answer 1

Using 'mapping' instead of array-of-struct, gives you better control over your state variables with no extra hassles to control the array indexes. It also costs lower gas fee.
mapping(uint => uint[]) Singer;
mapping(uint => uint[]) Event;
uint public n_singers;
uint public n_events;
function CreateEvent(uint singer_id) external {
if(singer_id > n_singers) {
revert SingerIdError(singer_id);
}
else if (singer_id == n_singers) {
n_singers ++;
Singer[singer_id].push(n_events); // HOW TO APPEND THE EVENT ID TO THE LIS....
Event[n_events].push(singer_id);
} else {
Singer[singer_id].push(n_events);
}
n_events++;
}`