How to add entered text to the dropdown collection in Xamarin.Forms DataForm (SfDataForm)

You can add the entered text to the DropDown editor’s collection in Xamarin.Forms SfDataForm by using a custom editor.

You can create and add the custom editor to SfDataForm by overriding the DataFormEditor class, where the CustomDropDownEditor is inherited using DataFormDropDownEditor.

Refer to the online user guide documentation for creating a new custom editor in DataForm.

You can also refer the following article.

https://www.syncfusion.com/kb/11402/how-to-add-entered-text-to-the-dropdown-collection-in-xamarin-forms-dataform-sfdataform

C#

DropDown editor modified by customizing DataFormDropDownEditor. When unfocused from dropdown entered text added to the collection.

public class CustomDropDownEditor : DataFormDropDownEditor
{
    DataFormDropDownItem dropDownItem;
    SfDataForm sfDataForm;
    public CustomDropDownEditor(SfDataForm dataForm) : base(dataForm)
    {
        this.sfDataForm = dataForm;
    }
    protected override void OnInitializeView(DataFormItem dataFormItem, SfComboBox view)
    {
        base.OnInitializeView(dataFormItem, view);
        view.IsEditableMode = true;
        view.Unfocused += View_Unfocused; 
        dropDownItem = dataFormItem as DataFormDropDownItem;
    }
    private void View_Unfocused(object sender, Xamarin.Forms.FocusEventArgs e)
    {
        var dropDown = sender as SfComboBox;
        var text = dropDown.Text;
    if (string.IsNullOrEmpty(text))
        return;
        var selectedItem = dropDown.SelectedItem;
        if (selectedItem == null || (selectedItem as Details)?.Name?.ToString() != text)
        {
            dropDownItem.ItemsSource.Add(new Details { Name = text });
            (DataForm.DataObject as Address).Country = text;
            sfDataForm.UpdateEditor("Country");
        }
    }
  protected override void OnUnWireEvents(SfComboBox view)
  {
     base.OnUnWireEvents(view);
     view.Unfocused -= View_Unfocused;
  }
}

Refer to the following code example for binding DataObject and register the editor using RegisterEditor as CustomDropDownEditor to make data form items as a custom editor in DataForm.

C#

Customized DropDown editors registered to DataForm.

public class DataFormBehavior : Behavior<ContentPage>
{
    SfDataForm dataForm;
    protected override void OnAttachedTo(ContentPage bindable)
    {
        base.OnAttachedTo(bindable);
        dataForm = bindable.FindByName<SfDataForm>("dataForm");
        dataForm.SourceProvider = new SourceProviderContactForm();
        dataForm.RegisterEditor("DropDown", new CustomDropDownEditor(dataForm));
        dataForm.RegisterEditor("Country", "DropDown");
        dataForm.AutoGeneratingDataFormItem += DataForm_AutoGeneratingDataFormItem;
    }
    private void DataForm_AutoGeneratingDataFormItem(object sender, AutoGeneratingDataFormItemEventArgs e)
    {
        if (e.DataFormItem != null)
        {
            if (e.DataFormItem.Name == "Country")
            {
                (e.DataFormItem as DataFormDropDownItem).DisplayMemberPath = "Name";
                (e.DataFormItem as DataFormDropDownItem).SelectedValuePath = "Name";
            }
        }
    }
    protected override void OnDetachingFrom(ContentPage bindable)
    {
        base.OnDetachingFrom(bindable);
        dataForm.AutoGeneratingDataFormItem -= DataForm_AutoGeneratingDataFormItem;
    }
}

Output