无法检查列表是否包含C＃中的选择项

Question

I am storing a list of select items in my view model. When adding the correct select items i get them from a list stored in a spreadsheet, some of which are duplicates. I want to eliminate these duplicates and have the following code to do so.

        //Fill with all the install locations
        foreach (App y in applications)
        {
            //Check if the app has a server listed
            if (y.Server != "")
            {
                SelectListItem ItemToAdd = new SelectListItem { Text = y.Server, Value = y.Server };
                //Check if the the item has already been added to the list
                if (!vm_modal.serverLocations.Contains(ItemToAdd))
                {
                    vm_modal.serverLocations.Add(ItemToAdd);
                }
            }
        }

However this is not working as it is just adding everything so there are a lot of duplicates. I don't know if contains works differently because I'm not just dealing with regular strings or something like that.

Answer 1

In this instance, as you are using the same string for Text and Value , you can iterate through your source, and add non-duplicate values to a simple List<string> before adding all of the checked values to your select list.

List<string> result = new List<string>();

foreach (App y in applications)
{
    //Check if the app has a server listed and for duplicates
    if (y.Server != "" && !result.Contains(y.Server))
    {
            result.Add(y.Server);
    }
}

result.ForEach(x => vm_modal.serverLocations.Add(
                new SelectListItem(){Text = x, Value = x}));

Answer 2

for a "one liner" of what ste-fu presented you can write

vm_modal.serverLocations
    .AddRange(applications
               .Where(app => app.Server != "")
               .Select(app => app.Server)
               .Distinct()
               .Select(server => new SelectListItem{ Text = server, Value = server }));