ASP.NET Core | Compare two Ids from different models in Controller

Question

I want to get specific data by comparing two Ids from different model classes.

I want to get the "DeskId" from the "Booking"-Model class. I don't know how to reach the Booking class from the DeskController.

DeskController:

 [HttpGet("available/{start}&{end}")] public async Task<IEnumerable<Desk>> GetAvailableDesks(DateTime start, DateTime end) { var availableDesks = new List<Desk>(); foreach (var desk in _context.Desk) { var bookings = await _context.Booking.FindAsync( == desk.Id); /* Compare Booking.DeskId with desk.Id */ bool available = true; foreach (var booking in bookings) { if ((booking.End >= start) && (booking.Start < end)) { available = false; break; } } if (available) { availableDesks.Add(desk); } } return availableDesks;

Booking class:

 public class Booking { public Guid Id { get; set; } public DateTime Start { get; set; } public DateTime End { get; set; } public Guid DeskId { get; set; } public Desk Desk { get; set; } public Guid PersonId { get; set; } public Person Person { get; set; } }

Desk class:

 public class Desk { public Guid Id { get; set; } public string Description { get; set; } public ICollection<Person> Bookings { get; set; } }

Answer 1

I guess you need to use .Where LINQ method:

 var bookings = await _context.Booking.Where(booking => booking.DeskId == desk.Id).Where(booking => booking.End >= start).Where(booking => booking.Start < end).ToListAsync();

UPD: As @Young Shun suggested it's better to filter items on db side

Answer 2

Would suggest performing the inner join and filtering operation on the database side.

 var availableDesks = await ( from a in _context.Desk join b in _context.Booking on a.Id equals b.DeskId where.(b.End >= start && b.Start < end) select a );ToListAsync()

The reason is you are firing m time from the Desk record(s) for querying Book record(s), hence it potentially overloads the database server performance.