Get Clients endpoint

ClientsController.cs

// GET: api/Clients
[HttpGet("")
public IActionResult GetClients()
{
    var result = _context.Clients.Select(client => new Client()
    {
        ClientId = client.ClientId,
        FirstName = client.FirstName,
        LastName = client.LastName,
        Appointments = client.Appointments
    }).ToList();

    return Ok(result);
}