Get distinct list values
.net, asp.net, asp.net-mvc, c#
Solution
You need to define "identical" here. I'm guessing you mean "have the same contents", but that is not the default definition for classes: the default definition is "are the same instance".
If you want "identical" to mean "have the same contents", you have two options:
- write a custom comparer (`IEqualityComparer<Project>`) and supply that as a parameter to `Distinct`
- override `Equals` and `GetHashCode` on `Project`
There are also custom methods like `DistinctBy` that are available lots of places, which is useful if identity can be determined by a single property (`Id`, typically) - not in the BCL, though. But for example:
if (model != null) model = model.DistinctBy(x => x.Id).ToList();
With, for example:
public static IEnumerable<TItem>
DistinctBy<TItem, TValue>(this IEnumerable<TItem> items,
Func<TItem, TValue> selector)
{
var uniques = new HashSet<TValue>();
foreach(var item in items)
{
if(uniques.Add(selector(item))) yield return item;
}
}
Problem
i have a C# application in which i'd like to get from a `List` of Project objects , another List which contains distinct objects. i tried this ``` List<Project> model = notre_admin.Get_List_Project_By_Expert(u.Id_user); if (model != null) model = model.Distinct().ToList(); ``` The list model still contains 4 identical objects `Project`. What is the reason of this? How can i fix it?