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; }
}

As to your question, it should be something like FindAsync(x => x.DeskId == desk.Id) — Fildor
– Fildor, Commented Jul 4, 2022 at 9:59
@Fildor I already tried that but then he says "The delegate type could not be inferred.". — Joshua
– Joshua, Commented Jul 4, 2022 at 10:00
After having fixed that, does it still show the exception you mentioned above (delegate type could not ... ) — Fildor
– Fildor, Commented Jul 4, 2022 at 10:05
Yes, it still shows that. But I just use the Answer from Romada Koliada. This works fine for me. — Joshua
– Joshua, Commented Jul 4, 2022 at 10:31

Roman Koliada · Accepted Answer · 2022-07-04 10:14:26Z

2

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

edited Jul 4, 2022 at 10:14

answered Jul 4, 2022 at 9:58

Roman Koliada

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Comments

Yong Shun · Accepted Answer · 2022-07-04 10:16:06Z

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.

edited Jul 4, 2022 at 10:16

answered Jul 4, 2022 at 10:08

Yong Shun

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