Question

I have the below model which represents a two level menu hierarchy and what I need to do is select one ID from the SubMenuItems sub collection then concatenate the results from its and its parent records TextToDisplay properties.

The question I have is how to return a single parent item and a single sub item then access the TextToDisplay property?

The object that I want to query is an ObserableCollection

public ObservableCollection<MenuModel> MenuItems { get; set; }

Model

public class MenuModel
{
    public int ID { get; set; }
    public string TextToDisplay { get; set; }
    public string ImageSource { get; set; }
    public ObservableCollection<MenuModel> SubMenuItems { get; set; }
}

Answer 1

Use Single() to get one item, and Any() to check if there is an element of a list which matches a query:

int theIdYouWant = 30; //for example
var parentItem = MenuItems.Single(i => i.SubMenuItems.Any(si => si.Id == theIdYouWant));
var text = parentItem.TextToDisplay + 
    parentItem.SubMenuItems.Single(i => i.Id == theIdYouWant).TextToDisplay;

Note this will throw an exception if no parent item contains a sub item with the ID of 30, or if more than one parent item is returned – so you may need to use SingleOrDefault() instead and check for null, or Where and then choose which item you want.