vb2008 search through listbox using textbox - vb.net

Question

hi I have a form that find, or should I say filter, the items in a listbox using a textbox. I have a textbox used for searching and a listbox populated with items from database. Now, say listbox items include apple, banana, berry, cashew, lemon, mango, peanut. If I typed 'b' on the textbox, listbox only show banana and berry..if I typed 'ba' then listbox only show banana but if I typed 'be' then it shows berry and so on. I already got this working (with the code marked as commented in the txtSearch event). My problem is that how can I bring the items in the listbox back when the user strike the backspace? Because, say I have banana and berry in the listbox now, when I erased the text that I typed in the textbox it should list back all the items again so that if I want to search another item it will be filtered again. thanks in advance.
Code Update
Public Class Glossary
Private Sub Glossary_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Call List()
Refreshlist()
End Sub
Private Sub List()
Dim myCmd As New MySqlCommand
Dim myReader As MySqlDataReader
Dim myAdptr As New MySqlDataAdapter
Dim myDataTable As New DataTable
Call Connect()
With Me
STRSQL = "Select word from glossary"
Try
myCmd.Connection = myConn
myCmd.CommandText = STRSQL
myReader = myCmd.ExecuteReader
If (myReader.Read()) Then
myReader.Close()
myAdptr.SelectCommand = myCmd
myAdptr.Fill(myDataTable)
lstword.DisplayMember = "word"
lstword.ValueMember = "word"
If myDataTable.Rows.Count > 0 Then
For i As Integer = 0 To myDataTable.Rows.Count - 1
lstword.Items.Add(myDataTable.Rows(i)("word"))
Next
End If
End If
'lstword.Items.Clear()
'lstword.Items.AddRange(word.Where(Function(word) word.ToString().Contains(txtSearch.Text)).ToArray())
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
myReader = Nothing
myCmd = Nothing
myConn.Close()
Call Disconnect()
End With
End Sub
Dim word As List(Of Object)
Private Sub Refreshlist()
lstword.Items.Clear()
lstword.Items.AddRange(word.Where(Function(word) word.ToString().Contains(txtSearch.Text)).ToArray())
End Sub
Private Sub txtSearch_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSearch.TextChanged
lstword.Items.Clear()
lstword.Items.AddRange(word.Where(Function(word) word.ToString().Contains(txtSearch.Text)).ToArray())
Refreshlist()
'Call List()
'lstword.BeginUpdate()
'Try
' ' keep track of the "non-searched items" '
' Dim word As New List(Of Object)
' lstword.SelectedIndices.Clear()
' If txtSearch.Text.Length > 0 Then
' For index As Integer = 0 To lstword.Items.Count - 1
' Dim item As String = lstword.Items(index).ToString()
' If item.IndexOf(txtSearch.Text, StringComparison.CurrentCultureIgnoreCase) >= 0 Then
' lstword.SelectedIndices.Add(index)
' Else
' ' this item was not searched for; we will remove it '
' word.Add(index)
' End If
' Next
' ' go backwards to avoid problems with indices being shifted '
' For i As Integer = word.Count - 1 To 0 Step -1
' Dim indexToRemove As Integer = word(i)
' lstword.Items.RemoveAt(indexToRemove)
' Next
' End If
'Finally
' lstword.EndUpdate()
'End Try
End Sub
End Class

Answer 1

The first step is to store the items in off-screen memory. For instance:
Dim words As List(Of Object)
Then when you refresh the list box, only populate it with the items from that in-memory list which match the current criteria:
lstword.Items.Clear()
lstword.Items.AddRange(
words.FindAll(
Function(word) Return word.ToString().Contains(txtSearch.Text)
).ToArray()
)
Or, using LINQ:
lstword.Items.Clear()
lstword.Items.AddRange(
words.Where(
Function(word) word.ToString().Contains(txtSearch.Text)
).ToArray()
)
UPDATE
Since you seem to be having trouble getting it working, and it's hard to say what's wrong with your code without actually seeing it, here's a complete working example:
Public Class Form1
Dim words As New List(Of Object)(New String() {"apple", "banana", "berry", "cashew", "lemon", "mango", "peanut"})
Private Sub RefreshList()
lstword.Items.Clear()
lstword.Items.AddRange(
words.Where(
Function(word) word.ToString().Contains(txtSearch.Text)
).ToArray()
)
End Sub
Private Sub txtSearch_TextChanged(sender As Object, e As EventArgs) Handles txtSearch.TextChanged
RefreshList()
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
RefreshList()
End Sub
End Class
UPDATE 2
I tried using your code with my recommended suggestions and it worked fine. Here's the code that worked for me. Try it and let me know if it doesn't work for you:
Public Class Glossary
Private Sub Glossary_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
List()
Refreshlist()
End Sub
Private Sub List()
word.AddRange(New String() {"apple", "banana", "berry", "cashew", "lemon", "mango", "peanut"})
End Sub
Private word As New List(Of Object)()
Private Sub Refreshlist()
lstword.Items.Clear()
lstword.Items.AddRange(word.Where(Function(word) word.ToString().Contains(txtSearch.Text)).ToArray())
End Sub
Private Sub txtSearch_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtSearch.TextChanged
Refreshlist()
End Sub
End Class
If that works, then all you need to do is change the List method to load from the database instead of being a hard-coded list.

Answer 2

Get your initial list off the database, pop it in a List class e.g List.
The use your search text to select all the matching items and put them in the list box. Blank search text you just put all of them in.
You might want to have a look at Foreach and List.FindAll as well.