Tracking lists

public record Album(int Id, string Title);

List<Album> existingAlbums = cnn.Query<List<Album>>("SELECT AlbumId AS Id, Title FROM albums ORDER BY AlbumId");
static readonly QueryCommand DeleteAlbum = new("DELETE FROM albums WHERE AlbumId = @Id");

Structural tracking with a concrete type

TrackingList<Album> albums = new(existingAlbums);

albums.Add(new Album(0, "New album"));
albums.RemoveAt(0);

Console.WriteLine(albums.AddedCount);
Console.WriteLine(albums.RemovedCount);

TrackingList<T> tracks active membership and structural changes without requiring editable items.

Structural and member tracking together

TrackingList<IRuntimeTrackingItem<Album>> albums = existingAlbums.ToTrackingList();

albums[0].Set(nameof(Album.Title), "Kind of Blue");

Member changes belong to the items. Structural changes belong to the list.

bool structural = albums.HasChanges;
bool memberEdit = albums[0].HasChanges();

AddNew

IRuntimeTrackingItem<Album> item = albums.AddNew();
item.Set(nameof(Album.Title), "New album");

Console.WriteLine(albums.IsAddedAt(albums.Count - 1));

if (albums.CanAddNew)
    albums.AddNew();

An already created item can also be inserted.

albums.Add(edit);
albums.Insert(0, edit);

Remove

IRuntimeTrackingItem<Album> removed = albums[0];
albums.RemoveAt(0);

Console.WriteLine(albums.RemovedCount);

An accepted removed item remains in Removed until deletion is confirmed. Removing an item that is still a new addition cancels that addition instead.

Restore

IRuntimeTrackingItem<Album> removed = albums.Removed[0];
albums.Restore(removed);

albums.RestoreAt(0, 2);

Move

albums.Move(0, 3);

Moving changes active order without creating an addition or removal.

Replace

albums[2] = replacement;

The configured comparer determines whether the replacement represents the same item.

TrackingList<AlbumRow> rows = new(existingRows, comparer: EqualityComparer<AlbumRow>.Default);

Enumerate structural changes

foreach (IRuntimeTrackingItem<Album> item in albums.Added)
    Console.WriteLine(item.Get<string>(nameof(Album.Title)));

foreach (IRuntimeTrackingItem<Album> item in albums.Removed)
    Console.WriteLine(item.Get<int>(nameof(Album.Id)));

Confirm one active operation

bool confirmed = albums.ConfirmAt(0);

The specific operations are also exposed.

albums.ConfirmAddedAt(0);
albums.ConfirmEditAt(1);

Confirm a deletion

IRuntimeTrackingItem<Album> removed = albums.Removed[0];

DeleteAlbum.Execute(cnn, removed);
albums.ConfirmDelete(removed);

Confirm current operations

bool allConfirmed = albums.ConfirmChanges();

Persistence

Concrete item type

IEnumerable<AlbumRow> rows = existingRows;
TrackingList<AlbumRow> tracked = new(rows);

Application-defined list behavior can be supplied through ITrackingListContext<T>.