SdtListItemCollection Class

public class SdtListItemCollection : IEnumerable<SdtListItem>, 
	IEnumerable

Public Class SdtListItemCollection
	Implements IEnumerable(Of SdtListItem), IEnumerable

public ref class SdtListItemCollection : IEnumerable<SdtListItem^>, 
	IEnumerable

type SdtListItemCollection =  
    class
        interface IEnumerable<SdtListItem>
        interface IEnumerable
    end

// Create a blank document and insert a StructuredDocumentTag that will contain a drop down list
Document doc = new Document();
StructuredDocumentTag tag = new StructuredDocumentTag(doc, SdtType.DropDownList, MarkupLevel.Block);
doc.FirstSection.Body.AppendChild(tag);

// A drop down list needs elements, each of which will be a SdtListItem
SdtListItemCollection listItems = tag.ListItems;
listItems.Add(new SdtListItem("Value 1"));

// Each SdtListItem has text that will be displayed when the drop down list is opened, and also a value
// When we initialize with one string, we are providing just the value
// Accordingly, value is passed as DisplayText and will consequently be displayed on the screen
Assert.AreEqual(listItems[0].DisplayText, listItems[0].Value);

// Add 3 more SdtListItems with non-empty strings passed to DisplayText
listItems.Add(new SdtListItem("Item 2", "Value 2"));
listItems.Add(new SdtListItem("Item 3", "Value 3"));
listItems.Add(new SdtListItem("Item 4", "Value 4"));

// We can obtain a count of the SdtListItems and also set the drop down list's SelectedValue attribute to
// automatically have one of them pre-selected when we open the document in Microsoft Word
Assert.AreEqual(4, listItems.Count);
listItems.SelectedValue = listItems[3];

Assert.AreEqual("Value 4", listItems.SelectedValue.Value);

// We can enumerate over the collection and print each element
using (IEnumerator<SdtListItem> enumerator = listItems.GetEnumerator())
{
    while (enumerator.MoveNext())
    {
        if (enumerator.Current != null)
            Console.WriteLine($"List item: {enumerator.Current.DisplayText}, value: {enumerator.Current.Value}");
    }
}

// We can also remove elements one at a time
listItems.RemoveAt(3);
Assert.AreEqual(3, listItems.Count);

// Make sure to update the SelectedValue's index if it ever ends up out of bounds before saving the document
listItems.SelectedValue = listItems[1];

doc.Save(ArtifactsDir + "StructuredDocumentTag.ListItemCollection.docx");

// We can clear the whole collection at once too
listItems.Clear();
Assert.AreEqual(0, listItems.Count);