public static ListComparisonResult <T> CompareLists <T>(IList newList, IList existingList, List <string> propertyNames, Type returnType)
{
ListComparisonResult <T> result = new ListComparisonResult <T>();
if (existingList == null || existingList.Count == 0)
{
result.NewItems = (IList)GetListOfGivenType(newList, returnType);
}
else
{
result.NewItems = GetItemsNotPresentInSource <T>(existingList, newList, propertyNames, returnType, ref result);
}
if (newList == null || newList.Count == 0)
{
result.DeletedItems = (IList)GetListOfGivenType(existingList, returnType);
}
else
{
ListComparisonResult <T> nullObj = null;
result.DeletedItems = GetItemsNotPresentInSource <T>(newList, existingList, propertyNames, returnType, ref nullObj);
}
if (result.CommonItems.Count == 0)
{
result.CommonItems = (IList)Activator.CreateInstance(returnType);
}
return(result);
}
private static IList GetItemsNotPresentInSource <T>(IList listToCompare, IList source, List <string> propertyNames, Type returnType, ref ListComparisonResult <T> result)
{
object returnObj = Activator.CreateInstance(returnType);
object commonListObject = Activator.CreateInstance(returnType);
if (source != null)
{
PropertyInfo[] properties = typeof(T).GetProperties();
foreach (var item in source)
{
List <object> sourceProperties = new List <object>();
//add all comparison properties to a list
foreach (string propertyName in propertyNames)
{
PropertyInfo propertyInfo = properties.FirstOrDefault(x => x.Name == propertyName);
if (propertyInfo != null)
{
object sourceValue = propertyInfo.GetValue(item, null);
sourceProperties.Add(sourceValue);
}
}
if (listToCompare != null)
{
// compare with each element in the other list
if (!ContainsSameItem(sourceProperties, listToCompare, propertyNames))
{
((IList)returnObj).Add((T)item);
}
else
{
if (result != null)
{
((IList)commonListObject).Add((T)item);
}
}
}
}
}
if (result != null)
{
result.CommonItems = (IList)commonListObject;
}
return((IList)returnObj);
}