This sample introduces how to add a DataGridColumnStyle that contains combobox to a DataGrid on your .Net form. It is not just a dropdown combobox, which appears when a datagrid cell becomes the current cell. This .Net DataGrid DataGridColumnStyle combobox control has the following attractive features:

This combobox DataGridColumnStyle automatically fills the text at the cursor with the value of its dropdown values list. As characters are typed, the component finds the closest matching item from the list and automatically fills in the remaining characters. Appended characters are highlighted so that they are replaced by any further typing. For this auto-filling feature you can setup the character case sensibility.

This DataGridColumnStyle gives you ability to instantly update dropdown values with a really simple and friendly user interface. When you click the additional dropdown button of the combo a dictionary of its list values will be displayed below the combo. You can update values, and insert and delete rows in the dictionary grid.

The control gives an ability to get a nesting combo box that filters values from a related child table. In a dictionary grid, you can view and edit related data in a child table. In your database a Master table has a one-to-many relationship with a Child table; so for each row of the Master table in Dictionary grid, you or your customer can view and edit the related rows of the Child table in a dictionary grid.

You can turn off all or some of these features and use the combobox DataGridColumnStyle just as an easy dropdown DataGrid combobox.

You can set its DataSource, DisplayMember, and ValueMember to bind the combobox to a foreign table.

' Set datagrid column styles
With TableStyle.GridColumnStyles
' Set datagrid ColumnStyle for Car field
.Add(New DataGridTextBoxColumn(tblCrrncMngr.GetItemProperties.Item("Car")))
With .Item(0)
.MappingName = "Car"
.HeaderText = "Car Name"
.Width = 130
.NullText = String.Empty
.ReadOnly = True
End With

' Set datagrid ComboBox ColumnStyle for PubID field
.Add(New DataGridComboBoxColumn(ds.Tables.Item("Companies"), 1, 0))
' Datagrid ComboBox DisplayMember field has order number 1. Name of this column is "Name"
' Datagrid ComboBox ValueMember field has order number 0. Name of this column is "PubID"
With .Item(1)
.MappingName = "PubID"
.HeaderText = "Company ID"
.Width = 200
.NullText = String.Empty
End With

' Set datagrid combobox ColumnStyle for State field
.Add(New DataGridComboBoxColumn(ds.Tables.Item("States"), 0, 0, , , False))
' Datagrid ComboBox DisplayMember field has order number 0. Name of this column is "State"
' Datagrid ComboBox ValueMember field has order number 0. It is the same column like for DisplayMember
With .Item(2)
.MappingName = "State"
.HeaderText = "State"
.Width = 45
.NullText = String.Empty
End With

' Set datagrid XP Style Button ColumnStyle for City field
.Add(New DataGridXPButtonColumn())
' Also you may set datagrid Button ColumnStyle for City
' field without XP Button Style as the following:
' .Add(New DataGridButtonColumn())
With .Item(3)
.MappingName = "City"
.HeaderText = "City"
.Width = 60
.NullText = String.Empty
End With

' Set datagrid Memo ColumnStyle for Comments field
.Add(New DataGridMemoColumn("Car description"))
With .Item(4)
.MappingName = "Comments"
.HeaderText = "Comments"
.Width = 60
.NullText = String.Empty
End With
End With

How to search a list box by typing text into a combobox control? This example shows how to implement an auto-fill combo box. You often faced it on some sophisticated web pages. As characters are typed, the program finds the closest matching item from the combobox list and automatically fills in the remaining characters. A similar approach using event "Change" can be used to work with a text box and list box control.

VB .NET

VB6

Public Class Form1
Inherits System.Windows.Forms.Form

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load

' Retrieve all the Company Names in the table
Dim AppPath As String = Mid(Application.ExecutablePath, 1, Len(Application.ExecutablePath) - 14)
Dim strConn As String = "Provider=Microsoft.JET.OLEDB.4.0;Data Source = " + AppPath + "Samples.mdb"
Dim dbConn As System.Data.OleDb.OleDbConnection = _
New System.Data.OleDb.OleDbConnection(strConn)

dbConn.Open()
Dim DSet As New DataSet, SQLStr As String
Dim cmd As System.Data.OleDb.OleDbCommand
Dim dbAdaptr As System.Data.OleDb.OleDbDataAdapter = New System.Data.OleDb.OleDbDataAdapter

Dim tRow As DataRow, tTbl As DataTable
With dbAdaptr
.TableMappings.Add("Table", "Companies")
SQLStr = "Select [Company Name] from Companies"
cmd = New System.Data.OleDb.OleDbCommand(SQLStr, dbConn)
cmd.CommandType = CommandType.Text
.SelectCommand = cmd
.Fill(DSet)
.Dispose()
End With

DSet.AcceptChanges()
tTbl = DSet.Tables.Item(0)
DSet.Dispose()
dbConn.Close()

' fill out array by Company Names for cboRightCombo combobox
cboRightCombo.Text = ""
cboRightCombo.Items.Clear()
cboRightCombo.BeginUpdate()

' Load the Company Names into the ComboBox Control
For Each tRow In tTbl.Rows
cboRightCombo.Items.Add(tRow("Company Name").ToString)
Next
cboRightCombo.EndUpdate()
End Sub

' Close application
Private Sub cmdClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles cmdClose.Click
Me.Close()
End Sub

' Use event "Change" for alphabetical search an appropriate
' value in combo box list and put it into combobox Text.
Private Sub cboRightCombo_TextChanged(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles cboRightCombo.TextChanged
Dim boxIndex As Integer, lExst As Boolean
Dim box As ComboBox = sender
Dim txt As String = box.Text
Dim posCursor As Integer = box.SelectionStart
' If Cursor does not stay on the beginning of text box.
If posCursor <> 0 Then
lExst = False
' Go in cycle through the combo box list to
' find the appropriate entry in the list
For boxIndex = 0 To box.Items.Count - 1
If UCase(Mid(box.Items(boxIndex), 1, posCursor)) = UCase(Mid(txt, 1, posCursor)) Then
box.Text = box.Items(boxIndex)
box.SelectionStart = posCursor
lExst = True
Exit For
End If
Next
' We didn't find appropriate entry and return previous value to text box
If Not lExst Then
box.Text = Mid(txt, 1, posCursor - 1) + Mid(txt, posCursor + 1)
box.SelectionStart = posCursor - 1
End If
End If
End Sub

End Class

How to remove the duplicates in a string array? Here is an example of deleting double elements in an array. This example removes all the duplicate elements from the array InitialArray and create from it the new FinalArray.

Private i As Integer, InitialArray(6), FinalArray() As String

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
InitialArray(0) = "Acura"
InitialArray(1) = "BMW"
InitialArray(2) = "Acura"
InitialArray(3) = "Honda"
InitialArray(4) = "Toyota"
InitialArray(5) = "Acura"
InitialArray(6) = "BMW"

Label1.Text = ""
For i = 0 To UBound(InitialArray)
Label1.Text = Label1.Text + Trim(CStr(i)) + " = " + InitialArray(i) + vbLf
Next
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
FinalArray = DeleteDoubleElement(InitialArray)
Label2.Text = ""
For i = 0 To UBound(FinalArray)
Label2.Text = Label2.Text + Trim(CStr(i)) + " = " + FinalArray(i) + vbLf
Next
End Sub

' This function removes duplicate elements from a ReceivedArray().
' The function does not actually remove the elements. The resulting array
' will have a less than or equal number of elements than the original array.
' The final ReturnedArray() will be returned.
Private Function DeleteDoubleElement(ByRef ReceivedArray()) As String()
Dim ReturnedArray() As String
Dim col As New Scripting.Dictionary
For i = 0 To ReceivedArray.Length - 1
If Not col.Exists(CStr(ReceivedArray(i))) Then col.Add(CStr(ReceivedArray(i)), 1)
Next

ReDim ReturnedArray(col.Count - 1)
For i = 0 To col.Count - 1
ReturnedArray(i) = col.Keys(i)
Next

col = Nothing
Return ReturnedArray
End Function

DataGridXPButtonColumn allows you to provide the datagrid interface your users are requesting, while supporting the utterly powerful Microsoft .NET DataGrid control. The DataGridXPButtonColumn makes the MS .NET DataGrid control one of the most powerful controls that you ever had used. A RustemSoft DataGridXPButtonColumn column in a .net DataGrid control gives you ability to define custom functionality for items in the grid beyond the edit, delete, select, and hyperlink features of other column types. For example, you can use a DataGridXPButtonColumn to create a "Link to a website" button.
The DataGridXPButtonColumn has a pushbutton-style only. The button captions can be a text read from a database.
When you define a button column, you specify a command associated with the button. When users click the button, the button's command is passed to a container where you can handle it with your custom code.

' Set datagrid column styles
With TableStyle.GridColumnStyles
' Set datagrid ColumnStyle for Car field
.Add(New DataGridTextBoxColumn(tblCrrncMngr.GetItemProperties.Item("Car")))
With .Item(0)
.MappingName = "Car"
.HeaderText = "Car Name"
.Width = 130
.NullText = String.Empty
.ReadOnly = True
End With

' Set datagrid ComboBox ColumnStyle for PubID field
.Add(New DataGridComboBoxColumn(ds.Tables.Item("Companies"), 1, 0))
' Datagrid ComboBox DisplayMember field has order number 1. Name of this column is "Name"
' Datagrid ComboBox ValueMember field has order number 0. Name of this column is "PubID"
With .Item(1)
.MappingName = "PubID"
.HeaderText = "Company ID"
.Width = 200
.NullText = String.Empty
End With

......................

' Set datagrid XP Style Button ColumnStyle for City field
.Add(New DataGridXPButtonColumn(SystemColors.ControlText, SystemColors.Control))
' Also you may set datagrid Button ColumnStyle for City
' field without XP Button Style as the following:
' .Add(New DataGridButtonColumn())
With .Item(3)
.MappingName = "City"
.HeaderText = "City"
.Width = 60
.NullText = String.Empty
End With

End With

......................

' DataGridButtonAction function runs when the datagrid ButtonColumnStyle's
' Button control is clicked. The function receives two arguments:
' ColumnMappingName and ColumnValueAtRow of String type
Public Function DataGridButtonAction(ByVal ColumnMappingName As String, ByVal ColumnValueAtRow As String)
' You can identify datagrid column mapping name.
' It gives you ability to put several datagrid
' Button ColumnStyles on the same datagrid
If ColumnMappingName = "City" Then
Dim strValue As String
If IsDBNull(DataGrid1.Item(DataGrid1.CurrentRowIndex, 3)) Then
strValue = "Nothing :("
Else
strValue = ColumnValueAtRow + " city, " + DataGrid1.Item(DataGrid1.CurrentRowIndex, 2) + "!"
End If
MessageBox.Show("You have chosen " + strValue, "DataGrid Button is clicked!")
End If
End Function

The RustemSoft DataGridMemoColumn gives you a useful Memo Field control, which presents an edit window when user selects a cell of the DataGrid Memo Column on .NET DataGrid. This provides a pop-up memo field editor that you can call from your code at any time to let users edit the text in a memo field.
This Memo field editor provides more flexibility by updating the memo field to be used in a .NET DataGrid column.
The DataGrid Memo Column Memo field editor is useful for showing short document contents, like memos and emails.
When using the DataGrid Memo Column editor you are automatically provided with all general features, which any typical, contemporary word processor has.

' Set datagrid column styles
With TableStyle.GridColumnStyles
' Set datagrid ColumnStyle for Car field
.Add(New DataGridTextBoxColumn(tblCrrncMngr.GetItemProperties.Item("Car")))
With .Item(0)
.MappingName = "Car"
.HeaderText = "Car Name"
.Width = 130
.NullText = String.Empty
.ReadOnly = True
End With

' Set datagrid ComboBox ColumnStyle for PubID field
.Add(New DataGridComboBoxColumn(ds.Tables.Item("Companies"), 1, 0))
' Datagrid ComboBox DisplayMember field has order number 1. Name of this column is "Name"
' Datagrid ComboBox ValueMember field has order number 0. Name of this column is "PubID"
With .Item(1)
.MappingName = "PubID"
.HeaderText = "Company ID"
.Width = 200
.NullText = String.Empty
End With

.................................................

' Set datagrid Memo ColumnStyle for Comments field
.Add(New DataGridMemoColumn("Car description"))
With .Item(4)
.MappingName = "Comments"
.HeaderText = "Comments"
.Width = 60
.NullText = String.Empty
End With
End With

The DateTimePicker ColumnStyle is used to allow the user to select a date and time, and to display that date/time in your DataGrid.

' Set datagrid ComboBox ColumnStyle for PubID field
.Add(New DataGridComboBoxColumn(ds.Tables.Item("Companies"), 1, 0))
' Datagrid ComboBox DisplayMember field has order number 1. Name of this column is "Name"
' Datagrid ComboBox ValueMember field has order number 0. Name of this column is "PubID"
With .Item(1)
.MappingName = "PubID"
.HeaderText = "Company ID"
.Width = 200
.NullText = String.Empty
End With

.................................................

' Set datagrid DateTimePicker ColumnStyle for DateFirst field
.Add(New DataGridDateTimePicker())
With .Item(4)
.MappingName = "DateFirst"
.HeaderText = "Date"
.Width = 80
.NullText = String.Empty
End With
End With

You are trying to create a control in .NET, and your control has to catch the Tab key. It might be a grid, where you would expect Tab to move between cells, or it might be an editor control. Now you would like to catch Tab and some other navigation keys that do not call OnKeyDown or OnKeyUp. How to intercept Tabs properly in .NET?
You have to create a class that inherits from the System.Windows.Forms.Control and override the ProcessKeyMessage method. This method is called when a control receives a keyboard message. You suppose to trap the Tab on your Button. Just override the System.Windows.Forms.Button class and create your own MyButton class:

Public Class MyButton
Inherits System.Windows.Forms.Button
Public PreProcessKey As Integer = Nothing

Public Sub New()
MyBase.New()
End Sub

Protected Overrides Function ProcessKeyMessage(ByRef m As Message) As Boolean
PreProcessKey = m.WParam.ToInt32
End Function
End Class

In your custom code you will be able to identify which key has been pressed before your button was activated:

If MyButton.PreProcessKey = Keys.Tab Then MsgBox("Tab is pressed!")

These formatted intelligent DateTimeColumn, NumericColumn, TextFractionsColumn style controls can mask the date, time, numbers, digits, decimal as well as the text fractions. It gives you ability to manage the IP Address, SS#, Phone numbers, etc., and checks the validation, and automatically set the delimiter location.

' Set datagrid DateTime ColumnStyle for TimeFirst field
.Add(New DataGridDateTimeColumn(DateTimeTextBox.Stencils.HHMM24, Now, ":"))
With .Item(6)
.MappingName = "TimeFirst"
.HeaderText = "Time"
.Width = 40
.NullText = String.Empty
End With

' Set datagrid Numeric ColumnStyle for Price field
.Add(New RustemSoft.DataGridColumns.DataGridNumericColumn(, True, , , , , 2))
With .Item(7)
.MappingName = "Price"
.HeaderText = "Price"
.Width = 60
.NullText = String.Empty
End With

' Set datagrid TextFractions ColumnStyle for Phone field
.Add(New RustemSoft.DataGridColumns.DataGridTextFractionsColumn)
With .Item(8)
.MappingName = "Phone"
.HeaderText = "Phone"
.Width = 80
.NullText = String.Empty
End With

End With
End With
' Add TableStyle
DataGrid1.TableStyles.Add(TblStyle)

' Define NumericColumn DataGridNumericColumn object for Price field
Dim NumericColumn As DataGridNumericColumn = DataGrid1.TableStyles(0).GridColumnStyles(7)
' Specify back color for the field
NumericColumn.txtBox.box.BackColor = System.Drawing.Color.LightPink

' Identify PhoneColumn object that is the DataGridTextFractionsColumn?s ?child?
Dim PhoneColumn As DataGridTextFractionsColumn = DataGrid1.TableStyles(0).GridColumnStyles(8)
' Specify Delimiter Character for the field
PhoneColumn.txtBox.box.DelimiterChar = "-"

' Specify first fraction properties
' Alphanumeric symbols only are acceptable for the fraction
PhoneColumn.txtBox.box.FractionsCode(0, 0) = "a"
' You can insert 3 symbols only into the first fraction
PhoneColumn.txtBox.box.FractionsCode(0, 1) = 3

' Specify second fraction properties
' Numeric symbols only are acceptable for the fraction
PhoneColumn.txtBox.box.FractionsCode(1, 0) = "n"
' You can insert 3 symbols only into the second fraction
PhoneColumn.txtBox.box.FractionsCode(1, 1) = 3

' Specify third fraction properties
' Numeric symbols only are acceptable for the fraction
PhoneColumn.txtBox.box.FractionsCode(2, 0) = "n"
' You can insert 4 symbols only into the third fraction
PhoneColumn.txtBox.box.FractionsCode(2, 1) = 4

' To specify Password column only one text fraction must be defined:
'' To let accept any symbols for the fraction we need leave first array element empty:
'PhoneColumn.txtBox.box.FractionsCode(0, 0) = ""
'' You can insert 30 symbols only into the password fraction
'PhoneColumn.txtBox.box.FractionsCode(0, 1) = 30
'' Specify Password Character for the field
'PhoneColumn.txtBox.box.PasswordChar = "*"

When a beginner who has VB6 experience first time opens .NET and just going about making a form up he/she could notice there is no Line in the .NET toolbox. What happened, where did it go?
There is a difference from VB6 forms that Windows Forms .NET does not support the Line control.

The Line class is based on System.Drawing namespace that provides access to GDI+ basic graphics functionality. A Line control is a graphical control that displays a horizontal, vertical, or diagonal one-pixel-wide line that can't be changed directly. The Line control can be changed dynamically at run time.
The control class Line that is implemented in both languages (VB.Net and C#) is derived from System.Windows.Forms.Control. It overrides the OnPaint method to draw itself. The class will draw the line depending on its properties.

Line controls can be displayed on forms, in picture boxes, and in another visual controls. You can move or resize your Line object by altering its X_Left, X_Right, Y_Left, and Y_Right properties. Also you can setup its Color property.

Dim ln As New Line
ln.X_Left = 20
ln.Y_Left = 150
ln.X_Right = 100
ln.Y_Right = 10
ln.Color = Color.Blue