aspnet-migration-04.cs

public class AppMigrationEngine: BaseMigrationEngine
{
    private readonly AppDbContext _db;
    
    public AppMigrationEngine(AppDbContext db)
    {
        _db = db;
    }
    
    public override async Task <IEnumerable<Version>> GetAppliedVersionsAsync()
    {
        // Important: this method is called BEFORE EF Core migrations run.
        // On a fresh database, your table won't exist yet.
        if (!await _db.Database.CanConnectAsync()) return [];
        
        try
        {
            return await _db.MigrationHistory.Select(m => m.Version).ToListAsync();
        }
        catch
        {
            return [];
        }
    }
    
    public override async Task RegisterVersionAsync(Version version)
    {
        _db.MigrationHistory.Add(new MigrationRecord
        {
            Version = version,
                AppliedAt = DateTime.UtcNow
        });
        
        await _db.SaveChangesAsync();
    }
}