VB.NET Listview Multiple Column Filter

Instead of only filtering one column at a time and passing the current list in to further filter the results, how about having a single function that filters based on all the specified values at once:

1. Call a single "Filter" function from the TextChanged (or Validated) event of every filter Textbox.
2. In the Filter function, start by re-copying originalListItems into lwArticles.
3. Apply filters for each Textbox that has a value in sequence. (Call SearchCurrentList for each textbox, passing in lwArticles. Each step filters down the list further from the previous, but only doing work for textboxes that have values.)

Its hard to follow what you are trying to do, but i suggest if you are dealing with 6k items in a listview and want to filter them, perhaps you should use a databound gridview instead.

Then you can perform the search on the datasource, very simply:

Public Class Form1
Private _articleList As List(Of Article)

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    'populate _itemList somehow, for example from a database. Manually here for example purposes:
    _articleList = New List(Of Article) From {
        New Article("jenny cooks fish", "cooking"),
        New Article("a better sales team", "sales")}
    DataGridView1.DataSource = _articleList
End Sub


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim filtered As List(Of Article) = _articleList.Where(Function(x) x.Title.Contains("cook") AndAlso x.Category = "cooking").ToList
    DataGridView1.DataSource = filtered

End Sub
End Class

Public Class Article
Property Title As String
Property Category As String
'etc etc

Public Sub New(ByVal title As String, ByVal category As String)
    _Title = title
    _Category = category
End Sub
End Class

I managed to get it to work. For those wondering how, it's not that elegant - but it works!

I set tags on the GUI of the four textboxes (i omitted the cost textbox after further talk with the engineers). So..

tbSearchArticleNo.Tag = 1

tbSearchDesc.Tag = 2

tbPartNum.Tag = 4

tbManufacturer.Tag = 8

This isn't elegant because you will exponentially grow as you add textboxes. (be careful) Depending on the fields entered, a total is calculated which will then be treated by my FilterOriginalList(total)

Private Sub tbSearchArticleNo_TextChanged(sender As Object, e As System.EventArgs) Handles tbSearchArticleNo.TextChanged, tbSearchDesc.TextChanged, tbPartNum.TextChanged, tbManufacturer.TextChanged
    Dim tag1 As Integer = 0
    Dim tag2 As Integer = 0
    Dim tag3 As Integer = 0
    Dim tag4 As Integer = 0

    If tbSearchArticleNo.Text <> "" Then
        tag1 = tbSearchArticleNo.Tag
    End If

    If tbSearchDesc.Text <> "" Then
        tag2 = tbSearchDesc.Tag
    End If

    If tbPartNum.Text <> "" Then
        tag3 = tbPartNum.Tag
    End If

    If tbManufacturer.Text <> "" Then
        tag4 = tbManufacturer.Tag
    End If

    FilterOriginalList(tag1 + tag2 + tag3 + tag4)
End Sub

Here is my method:

Private Sub FilterOriginalList(ByRef tagCounter As Integer)
    Dim field1 As String = tbSearchArticleNo.Text
    Dim field2 As String = tbSearchDesc.Text.ToUpper()
    Dim field4 As String = tbPartNum.Text.ToUpper()
    Dim field8 As String = tbManufacturer.Text.ToUpper()

    lwArticles.BeginUpdate()

    'Clear listview
    lwArticles.Items.Clear()

    For Each item In originalListItems
        Dim currField1 = item.SubItems.Item(0).Text
        Dim currField2 = item.SubItems.Item(1).Text.ToUpper
        Dim currField4 = item.SubItems.Item(2).Text.ToUpper
        Dim currField8 = item.SubItems.Item(3).Text.ToUpper

        Select Case (tagCounter)
            Case 0
                lwArticles.Items.Add(item)
            Case 1
                If currField1.Contains(field1) Then
                    lwArticles.Items.Add(item)
                End If
            Case 2
                If currField2.Contains(field2) Then
                    lwArticles.Items.Add(item)
                End If
            Case 3
                If currField1.Contains(field1) And currField2.Contains(field2) Then
                    lwArticles.Items.Add(item)
                End If
            Case 4
                If currField4.Contains(field4) Then
                    lwArticles.Items.Add(item)
                End If
            Case 5
                If currField1.Contains(field1) And currField4.Contains(field4) Then
                    lwArticles.Items.Add(item)
                End If
            Case 6
                If currField2.Contains(field2) And currField4.Contains(field4) Then
                    lwArticles.Items.Add(item)
                End If
            Case 7
                If currField1.Contains(field1) And currField2.Contains(field2) And currField4.Contains(field4) Then
                    lwArticles.Items.Add(item)
                End If
            Case 8
                If currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
            Case 9
                If currField1.Contains(field1) And currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
            Case 10
                If currField2.Contains(field2) And currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
            Case 11
                If currField1.Contains(field1) And currField2.Contains(field2) And currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
            Case 12
                If currField4.Contains(field4) And currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
            Case 13
                If currField1.Contains(field1) And currField4.Contains(field4) And currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
            Case 14
                If currField2.Contains(field2) And currField4.Contains(field4) And currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
            Case 15
                If currField1.Contains(field1) And currField2.Contains(field2) And currField4.Contains(field4) And currField8.Contains(field8) Then
                    lwArticles.Items.Add(item)
                End If
        End Select
    Next
    lwArticles.EndUpdate()
End Sub

Thanks for everyone who helped. Here's the solution I found - there's probably something much easier that I will be looking into in the futur!