Filtering items in a Listview

Question

I am trying to filter items in a ListView by using a TextBox.
I've managed to make something, but it can only delete items from my listview, not bring them back. Here is a little example of my code:

private void textBox1_TextChanged(object sender, EventArgs e)
{
    string value = textBox1.Text.ToLower();
    for (int i = listView1.Items.Count - 1; -1 < i; i--)
    {
        if
        (listView1.Items[i].Text.ToLower().StartsWith(value) == false)
        {
            listView1.Items[i].Remove();
        }
    }
}  

Does anybody has an idea on how to retrieve the deleted items? I can't seem to figure it out >:...

Brucie

You can't. Items is an ordinary collection; once you remove the items, they're gone. You would have to store the removed items somewhere (perhaps in another collection) if you wanted to restore them later. – Inconformity

How you bind the ListView? can you update the code related to data binding? – Pectize

Answer 1

check below sample app

using System;
using System.Windows.Forms;
using System.Collections.Generic;
using System.Linq;
public partial class Form1 : Form
{
    // keep list of listview items 
    List<Data> Items = new List<Data>();

    public Form1()
    {
        InitializeComponent();
        // get initial data
        Items = new List<Data>(){
            new Data(){ Id =1, Name ="A"},
            new Data(){ Id =2, Name ="B"},
            new Data(){ Id =3, Name ="C"}
        };

        // adding initial data
        listView1.Items.AddRange(Items.Select(c => new ListViewItem(c.Name)).ToArray());
    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {
        listView1.Items.Clear(); // clear list items before adding 
        // filter the items match with search key and add result to list view 
        listView1.Items.AddRange(Items.Where(i=>string.IsNullOrEmpty(textBox1.Text)||i.Name.StartsWith(textBox1.Text))
            .Select(c => new ListViewItem(c.Name)).ToArray());
    }

}

class Data
{
    public int Id { get; set; }
    public string Name { get; set; }
}

Pectize

NOTE: This does not work if you use a DataContext! ;) – Gumma

This will not work with subitems and also lose any other featrues of the listviewitems like tags etc. Instead of the class a simple List<>ListViewItem> would be a much better storage. – Valvulitis

Answer 2

You can change your logic and first search the items to delete, them delete they.

IList<Object> itemsToDelete = new List<Object>( listView1.find(delegate(string text){
     return !text.ToLower().StartsWith(value);
}));

listView1.Remove(itemsToDelete);
return itemsToDelete;

But you have to return another list. When you delete the items form the original list, you cant recovery It. You have to store it in another list.

Cristobalcristobalite

Answer 3

After trying to find a solution and giving up on searching I created this simple method and it worked for me.

    public static void FilterList(ListView list, string text)
    {
        if (text.Length > 0)
        {
            foreach (ListViewItem item in list.Items)
            {
                if (!item.ToString().ToLower().Contains(text.ToLower()))
                {
                    list.Items.Remove(item);
                }
            }
        }
        else 
        {
            UpdateList(list);
        }
    }

Ptisan

Answer 4

listBox1.Items.AddRange(listBox1.Items.Cast<String>    ().Where(X=>X.StartsWith(textBox1.Text)).ToArray());

Link

Works the same way with ListView.

Hope it helps

Tourneur

I've changed the code into: ` listView1.Items.AddRange(listView1.Items.Cast<String>().Where(X => X.StartsWith(textBox1.Text)).ToArray());` but I get an error saying: (screenshot) -> puu.sh/2TpSG.png – Brucie

ListViewItem[] list = listView1.Where(X => X.StartsWith(textBox1.Text)).ToArray(); Now clear the listview and assign the new list to the listview: listView1.Items.Clear(); listView1 = list; – Tourneur

cannot convert from 'string' to 'System.Windows.Forms.ListViewItem[]' – Namnama