search in DataGridView

Question

Hello experts

I need to select some DataGridView rows based on the user text input, some sort of search, so:

For loop As Integer = 0 To DataGridView.Rows.Count - 1
    If DataGridView.Item(0, loop).Value.ToString.ToLowerInvariant.Contains(SearchTextBoxDropDown.Text.ToLowerInvariant) = True Then
        DataGridView.Rows.Item(loop).Selected = True
    End If
Next

Then scroll to the first selected row:

Dim FirstRow As Integer = DataGridView.SelectedRows(0).Index
For loop2 As Integer = 0 To DataGridView.SelectedRows.Count - 1
    If DataGridView.SelectedRows(loop2).Index < FirstRow Then
        FirstRow = DataGridView.SelectedRows(loop2).Index
    End If
Next
DataGridView.FirstDisplayedScrollingRowIndex = FirstRow

This combination works, but is very slow when there are a large number of rows (the second part is slower)

Is there some implemented methods that can increase the performance and speed of such operation, or if not, am I doing something inefficiently?

Thanks for advise :)

Answer 1

Hi @StewartBW ,

You can use LINQ to make the code more concise and potentially more efficient.

DataGridView.ClearSelection()

Dim searchText As String = SearchTextBoxDropDown.Text.ToLowerInvariant()
Dim matchingRows = (From row As DataGridViewRow In DataGridView.Rows
                    Where row.Cells(0).Value.ToString().ToLowerInvariant().Contains(searchText)
                    Select row.Index).ToList()

For Each rowIndex As Integer In matchingRows
    DataGridView.Rows(rowIndex).Selected = True
Next

If matchingRows.Count > 0 Then
    DataGridView.FirstDisplayedScrollingRowIndex = matchingRows(0)
End If

Best Regards.

Jiachen Li

---

If the answer is helpful, please click "Accept Answer" and upvote it.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

Using a BindingList<T> as the DataSource for element lookup is fast

Imports System.ComponentModel

Public Class Form1

    Class Item
        Implements INotifyPropertyChanged

        Private _Name As String

        Public Property Name As String
            Get
                Return _Name
            End Get
            Set(value As String)
                If (value Is Nothing) Then
                    _Name = String.Empty
                    LowerInvariant = String.Empty
                Else
                    _Name = value
                    LowerInvariant = value.ToLowerInvariant()
                End If
                OnPropertyChanged(NameOf(Name))
            End Set
        End Property

        Public LowerInvariant As String

        Protected Overridable Sub OnPropertyChanged(propertyName As String)
            RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
        End Sub

        Public Event PropertyChanged As PropertyChangedEventHandler _
                Implements INotifyPropertyChanged.PropertyChanged
    End Class

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        DataGridView1.AllowUserToAddRows = False
        Dim list As New BindingList(Of Item)()
        For i As Integer = 1 To 10000
            list.Add(New Item With {.Name = GenerateRandomString()})
        Next
        DataGridView1.DataSource = list
    End Sub

    Dim random As New Random()

    Function GenerateRandomString() As String
        Dim length As Integer = GetRandomNumber(10, 15)
        Dim chars As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
        Dim stringChars(length - 1) As Char
        For i As Integer = 0 To stringChars.Length - 1
            stringChars(i) = chars(Random.Next(chars.Length))
        Next
        Return New String(stringChars)
    End Function

    Function GetRandomNumber(min As Integer, max As Integer) As Integer
        Dim random As New Random()
        Return random.Next(min, max + 1)
    End Function

    Sub Search1()
        DataGridView1.ClearSelection()
        Dim searchText As String = SearchTextBoxDropDown.Text.ToLowerInvariant()
        Dim firstRowIndex As Integer = -1
        For i As Integer = 0 To DataGridView1.Rows.Count - 1
            If DataGridView1.Item(0, i).Value.ToString.ToLowerInvariant.Contains(searchText) = True Then
                DataGridView1.Rows.Item(i).Selected = True
                If firstRowIndex = -1 Then
                    firstRowIndex = i
                End If
            End If
        Next
        If firstRowIndex <> -1 Then
            DataGridView1.FirstDisplayedScrollingRowIndex = firstRowIndex
        End If
    End Sub

    Sub Search2()
        DataGridView1.ClearSelection()
        Dim list As BindingList(Of Item) = DirectCast(DataGridView1.DataSource, BindingList(Of Item))
        Dim searchText As String = SearchTextBoxDropDown.Text.ToLowerInvariant()
        Dim firstRowIndex As Integer = -1
        For i As Integer = 0 To list.Count - 1
            If list(i).Name.ToLowerInvariant().Contains(searchText) Then
                DataGridView1.Rows.Item(i).Selected = True
                If firstRowIndex = -1 Then
                    firstRowIndex = i
                End If
            End If
        Next
        If firstRowIndex <> -1 Then
            DataGridView1.FirstDisplayedScrollingRowIndex = firstRowIndex
        End If
    End Sub

    Sub Search3()
        DataGridView1.ClearSelection()
        Dim list As BindingList(Of Item) = DirectCast(DataGridView1.DataSource, BindingList(Of Item))
        Dim searchText As String = SearchTextBoxDropDown.Text.ToLowerInvariant()
        Dim firstRowIndex As Integer = -1
        For i As Integer = 0 To list.Count - 1
            If list(i).LowerInvariant.Contains(searchText) Then
                DataGridView1.Rows.Item(i).Selected = True
                If firstRowIndex = -1 Then
                    firstRowIndex = i
                End If
            End If
        Next
        If firstRowIndex <> -1 Then
            DataGridView1.FirstDisplayedScrollingRowIndex = firstRowIndex
        End If
    End Sub

    Shared Sub Watch(action As Action, count As Integer)
        Dim sw As New Stopwatch()
        sw.Start()
        For i As Integer = 1 To count
            action.Invoke()
        Next
        sw.Stop()
        Dim elapsed As String = sw.Elapsed.ToString()
        Debug.WriteLine(elapsed)
        MessageBox.Show(elapsed)
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Watch(AddressOf Search1, 10)
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Watch(AddressOf Search2, 10)
    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        Watch(AddressOf Search3, 10)
    End Sub

End Class