Populate Spinner with Data from Firebase Database Table Xamarin

Question

I want to populate a spinner with a list of strings from a table in my firebase database.

I want the spinner to contain the items category name , so Test, Nature etc.

My xaml looks like this:

<Spinner
    android:spinnerMode="dialog"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:id="@+id/spinnerCategory"
    android:layout_margin="7dp" />

From here I am not sure as to how to populate the spinner with data.

Answer 1

I want to populate a spinner with a list of strings from a table in my firebase database.

First, please make sure, you have retrieved the data correctly:

protected override void OnCreate(Bundle savedInstanceState)
{
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.Database);

        ...
        spinnerCategory = FindViewById<Spinner>(Resource.Id.spinnerCategory);

        FirebaseApp.InitializeApp(this);

        reference = FirebaseDatabase.Instance.Reference;
        database = FirebaseDatabase.Instance;
        if (reference != null)
        {
            //add value event listener to categories of your database.
            reference.Child("categories").AddValueEventListener(this);
        }
}

public void OnDataChange(DataSnapshot snapshot)
{
        List<string> categories=RetrieveCategories(snapshot);
        UpdateSpinner(categories);
}

private List<string> RetrieveCategories(DataSnapshot snapshot)
{
    List<string> categories = new List<string>();
    var children=snapshot.Children.ToEnumerable<DataSnapshot>();
    HashMap map;
    foreach (var s in children)
    {
        map = (HashMap)s.Value;
        if (map.ContainsKey("categoryName"))
        {
            categories.Add(map.Get("categoryName").ToString());
        }
    }

    return categories;
}

Notes: I upload data using HashMap, so when retrieving data, I also convert it back to hashmap.

Then create your UpdateSpinner method to fill the SPinner:

private void UpdateSpinner(List<string> categories)
{
    ArrayAdapter<string> adapter = new ArrayAdapter<string>(this, Resource.Layout.spinner_item_view, Resource.Id.text_item, categories);
    spinnerCategory.Adapter = adapter;
}

And the Spinner will be filled correctly: