How to find which of the items are modified in a list when we work on client side and send it to server side in Asp.net MVC - asp.net-mvc

Question

I am working on SOA based project and i got got a situation where I am sending the whole array of object to server and then I have to see which of the objects are new and which one I have to update, hence I am looking for some generic function which can get me the list with update , delete or insert attribute

Answer 1

I was facing the same problem where I was sending entity with multiple children entities. The challenge was to figure out what child entity has been updated, added or deleted. Here what I did.
Implemented IObjectWithState with ChildEntity. (Inspired from one of pluralsight entityframework video)
Pull the server side version of entity.
Invoked FindDifference to get the difference of Child entities on client and server
IList<ClassTicket> clientSideTickets = /// What received from client
IList<ClassTicket> serverSideTickets = /// What received from database
var diffTickets = FindDifference(clientSideTickets ,serverSideTickets ,
(ticket1, ticket2) => ticket1.Id == ticket2.Id,(ticket1, ticket2) => ticket1.Name == ticket2.Name && ticket1.NoOfTicketsAvailable == ticket2.NoOfTicketsAvailable && ticket1.Price == ticket2.Price);
public interface IObjectWithState
{
State State { get; set; }
}
// My Child Entity
public class ClassTicket: IObjectWithState
{
public int Id { get; set; }
public string Name { get; set; }
public decimal Price { get; set; }
public short NoOfTicketsAvailable { get; set; }
public State State { get; set; }
}
public static IEnumerable<T> FindDifference<T>(IEnumerable<T> clientList, IEnumerable<T> serverList, Func<T, T, bool> identityDetector, Func<T, T, bool> changeDetector) where T : IObjectWithState
{
var finalList = new List<T>();
var clientItems = clientList as T[] ?? clientList.ToArray();
var serverItems = serverList as T[] ?? serverList.ToArray();
foreach (var clientItem in clientItems)
{
bool foundInServerList = false;
foreach (var serverItem in serverItems)
{
if(identityDetector(clientItem, serverItem))
{
foundInServerList = true;
clientItem.State = !changeDetector(clientItem, serverItem) ? State.Modified : State.Unchanged;
finalList.Add(clientItem);
break;
}
}
if(!foundInServerList)
{
clientItem.State = State.Added;
finalList.Add(clientItem);
}
}
foreach (var serverItem in serverItems)
{
var foundInClientList = clientItems.Any(clientItem => identityDetector(serverItem, clientItem));
if (!foundInClientList)
{
serverItem.State = State.Deleted;
finalList.Add(serverItem);
}
}
return finalList;
}