当使用多个表时，如何从XAML ListView获取ID？

Question

I am populating a ListView with SQLite data from two or more tables. When selecting from table I wish to get the ID of the selected item but lv.SelectedItem is returning a null value. No trouble with single tables.

I have searched everywhere and most people are just having problems joining the tables and haven't got as far as selecting.

Classes

public int ShoppingListID
{
    get { return listID; }
    set { listID = value;}
}
public int ShopID
{
    get { return shopID; }
    set { shopID = value; }
}

public int ShopID
{            
    get { return shopID; }
    set { shopID = value; }
}

public string ShopName
{
    get { return shopName; }
    set { shopName = value; }
}

Join code (which works perfectly)

using (SQLiteConnection conn = new SQLiteConnection(App.DatabaseLocation))
{               
    var allList = (from s in conn.Table<ShoppingLists>() join p in 
                   conn.Table<Shops>() on s.ShopID equals 
                   p.ShopID select new
                   {
                       s.ShoppingListID,
                       p.ShopName
                   }).ToList();

    lvShoppingLists.ItemsSource = allList;
}

Bound to a Grid in XAML

<ListView x:Name="lvShoppingLists"             
          ItemSelected="LvShoppingLists_ItemSelected"> 
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <Grid>
                    <Label Grid.Column="0" 
                           TextColor="Black" 
                           Text="{Binding ShoppingListID}" />
                    <Label Grid.Column="1" 
                           TextColor="Black" 
                           Text="{Binding ShopName}" />
                </Grid>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

Obtain the ID of the selected item

private void LvShoppingLists_ItemSelected(object sender,             
    SelectedItemChangedEventArgs e)
{ 
    var selectedList = lvShoppingLists.SelectedItem as ShoppingLists;
    GlobalVariables.SelectedShoppingListID = selectedList.ShoppingListID;
    Navigation.PushAsync(new ShoppingListPage());
}

Everything compiles and runs fine, but upon selecting an item from the ListView on the mainpage var selectedList returns a null . Debug shows that the information ( id and Name ) is being carried to the selected item but not being converted. The null value means that the variable is unable to be used in the query for the new page and I get a database error. I suspect that it is to do with the fact that the the class Shopping list has two int entries and the name is causing the problem.

Answer 1

Answer turns out to be:

Use a new class AllLists

 public int ShoppingListID
    {
        get { return listID; }
        set { listID = value; }
    }

    public string ShopName
    {
        get { return shopName; }
        set { shopName = value; }
    }

using (SQLiteConnection conn = new SQLiteConnection(App.DatabaseLocation))
{               
var allList = (from s in conn.Table<ShoppingLists>() join p in 
               conn.Table<Shops>() on s.ShopID equals 
               p.ShopID select new **AllLists**
               {
                   ShoppingListID = s.ShoppingListID,
                   ShopName = p.ShopName
               });

lvShoppingLists.ItemsSource = allList;
}

The selected item ID can then be 
var selectedList = lvShoppingLists.SelectedItem as AllLists;
GlobalVariables.SelectedShoppingListID = selectedList.ShoppingListID;
Navigation.PushAsync(new ShoppingListPage());