Question

I’m trying to create a listbox with categories and another listbox for items in each category. I want to be able to select a category in the first listbox and then the second listbox will change to display the items for that particular category. Its very common and I’m sure you can understand what I mean here. I was looking around for it but couldn’t get any idea how to do this. I’ve created 2 listboxes for the moment and the values I want in it, thats it. any help?

Answer 1

I created a winform with two list boxes listbox1 and listbox2 and this is what my Form1.cs looks like

namespace WinFormsApp
{
    public partial class Form1 : Form
    {
        private List<Category> categories;

        public Form1()
        {
            InitializeComponent();

            categories = new List<Category>();

            var categoryOne = new Category { Name = "Category 1"} ;
            categoryOne.Items.Add( new CategoryItem { Name = "Item 1"} );

            var categoryTwo = new Category { Name = "Category 2" };
            categoryTwo.Items.Add( new CategoryItem { Name = "Item 2" } );

            categories.Add( categoryOne );
            categories.Add( categoryTwo );
        }

        private void Form1_Load(object sender, System.EventArgs e)
        {
            categoryBindingSource.DataSource = categories;
        }
    }

    public class Category
    {
        public string Name { get; set; }

        public List<CategoryItem> Items { get; private set; }

        public Category()
        {
            Items = new List<CategoryItem>();
        }
    }

    public class CategoryItem
    {
        public string Name { get; set; }
    }
}

and here is the InitializeComponent() code

            this.listBox1.DataSource = this.categoryBindingSource;
            this.listBox1.DisplayMember = "Name";
            this.listBox1.FormattingEnabled = true;
            this.listBox1.Location = new System.Drawing.Point(24, 24);
            this.listBox1.Name = "listBox1";
            this.listBox1.Size = new System.Drawing.Size(242, 238);
            this.listBox1.TabIndex = 0;
            this.listBox1.ValueMember = "Items";

            this.categoryBindingSource.DataSource = typeof(Category);

            this.listBox2.DataSource = this.itemsBindingSource;
            this.listBox2.FormattingEnabled = true;
            this.listBox2.Location = new System.Drawing.Point(286, 24);
            this.listBox2.Name = "listBox2";
            this.listBox2.Size = new System.Drawing.Size(276, 238);
            this.listBox2.TabIndex = 1;
            this.listBox2.ValueMember = "Name";

            this.itemsBindingSource.DataMember = "Items";
            this.itemsBindingSource.DataSource = this.categoryBindingSource;