Spinner Control in Monodroid - Get ID and Text on Selection - xamarin.android

Question

I have started exploring the Spinner control just now. I have pretty much achieved what I wanted but only the last step is missing. Here is what I have done so far.
I have a very simple class for this example:
[Serializable]
public class Merchant
{
public Int64 MerchantId { get; set; }
public String ShopName { get; set; }
public override string ToString()
{
return ShopName;
}
}
Here is the axml where I placed the Spinner:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="1280dip"
android:layout_height="800dip">
<TextView
android:text="Select a merchant:"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="#+id/lblSelect"
android:layout_marginLeft="30dip"
android:layout_marginTop="30dip"
android:textSize="42dip" />
<Spinner
android:id="#+id/spinMerchant"
android:layout_width="1000dip"
android:layout_height="wrap_content"
android:layout_below="#id/lblSelect"
android:prompt="#string/spinner_prompt"
android:layout_centerHorizontal="true"
android:minHeight="20dip" />
</RelativeLayout>
And my code is:
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
// Create your application here
this.SetContentView(Resource.Layout.MerchantSelect);
List<Merchant> lstMerchant = new List<Merchant> ();
lstMerchant.Add (new Merchant() { ShopName = "First Shop", MerchantId = 11 });
lstMerchant.Add (new Merchant() { ShopName = "Second Shop", MerchantId = 12 });
Spinner spinner = this.FindViewById<Spinner>(Resource.Id.spinMerchant);
ArrayAdapter adapter = new ArrayAdapter (this, Android.Resource.Layout.SimpleSpinnerItem, lstMerchant);
spinner.ItemSelected += new EventHandler<AdapterView.ItemSelectedEventArgs> (spinner_ItemSelected);
spinner.Adapter = adapter;
}
private void spinner_ItemSelected (object sender, AdapterView.ItemSelectedEventArgs e)
{
Spinner spinner = (Spinner)sender;
//Merchant merch = (Merchant)spinner.SelectedItem;
string toast = string.Format ("Selected text is {0}", spinner.GetItemAtPosition (e.Position));
Toast.MakeText (this, toast, ToastLength.Long).Show ();
}
I want to get the selected text as well as the ID behind it as soon as the selection is made. I get the text by spinner.GetItemAtPosition (e.Position) but I can't seem to find anything that can give me the ID. If I try to do Merchant merch = (Merchant)spinner.SelectedItem; I get an exception: Cannot convert type 'Java.Lang.Object' to 'Merchant'.
Please let me know how it can be achieved.
Thanks.

Answer 1

The spinner only knows about the text because that's what you have in your ToString() method it. The adapter that's providing the spinner data has no idea it is dealing with Merchant objects.
To get to the actual Merchant object, youll have to make your List<Merchant> lstMerchant a member of your class.
Then change your selection handler:
private void spinner_ItemSelected (object sender, AdapterView.ItemSelectedEventArgs e)
{
Spinner spinner = (Spinner)sender;
// Get the ID from your model.
Merchant merch = this.lstMerchant[e.Position];
var id = merch.MerchantId;
string toast = string.Format ("Selected text is {0}", spinner.GetItemAtPosition (e.Position));
Toast.MakeText (this, toast, ToastLength.Long).Show ();
}