overriding DataGridTextBoxColumn implementation settings display with actual column values! (for example, sex display)

datagrid| Display

Here we talk about how to do data column content and display operation method. This approach is similar to implementation: There is data table test (ID int not NULL PRIMARY key, name varchar (), sex bit), then there is no way to use SQL statements directly, such as: Select ID, name, sex =c ASE Sex (When True Then ' man ' when false Then ' woman ' else sex end) to build to show "male", "female", and actually store true and false? Of course, if we use datagridboolcolumn, we can achieve a similar effect by setting some of its properties (Truevalue,falsevalue), but for those not bit columns? The answer is yes. We use the inheritance DataGridTextBoxColumn class, and then rewrite the Getcolumnvalueatrow method to achieve the effect. Getcolumnvalueatrow method, take the data from the data source, and then judge, return the value we want to display in the grid. (Code see the detailed code later)

In this way, we can successfully display the data we want in the grid, but there is another problem, that is, if we want to modify the data in the grid, can we be submitted to the database? If only through the above operation, only to achieve the purpose of the display, but also to rewrite the Edit,commit,abort method to achieve the click of the cell after the modified content, and then submit, and finally updated to the database.

Effect Figure 1 Below is the complete code of the program, here is just a comment, I hope you can make corresponding improvement according to the need 。

'************************************************************************************

' Program name: Cansetvaluedatagridtextbox

' Function Description: Inherits from DataGridTextBoxColumn class's column style, mainly realizes display value and the actual value display and the update

' Parameter description: None

' Return value: Cansetvaluedatagridtextbox

' Writer: Min

' Date time: 2005-06-16 a.m.

' Legacy problem: Clicking the column header sort will change the display value, is this a bug? Remains to be resolved

'************************************************************************************

Public Class Cansetvaluedatagridtextbox

Inherits System.Windows.Forms.DataGridTextBoxColumn

#Region "code generated by the Windows forms Designer"

Public Sub New ()

MyBase.New ()

' This call is required by the Windows Forms Designer.

InitializeComponent ()

' Add any initialization after the InitializeComponent () call

End Sub

' UserControl overrides dispose to clean up the list of components.

Protected Overloads Overrides Sub Dispose (ByVal disposing as Boolean)

If disposing Then

If not (components are nothing) Then

Components. Dispose ()

End If

End If

Mybase.dispose (disposing)

End Sub

' Required by the Windows Forms Designer

Private Components as System.ComponentModel.IContainer

' NOTE: The following procedure is required by the Windows Forms Designer

' You can use the Windows Forms Designer to modify this procedure.

' Do not modify it using the Code Editor.

<system.diagnostics.debuggerstepthrough () > Private Sub InitializeComponent ()

components = New System.ComponentModel.Container ()

End Sub

#End Region

Private rnum as Integer column ordinal

Private rname as String = "" ' Column name

Type of Private M_type as type column

Public Sub New (ByVal source as DataTable, ByVal rnum as Integer, ByVal displaytrue As String, ByVal TrueValue As String, _

ByVal Displayfalse As String, ByVal Falsevalue as String)

Rnum = Rnum

M_displaytrue = Displaytrue

M_valuetrue = TrueValue

M_displayfalse = Displayfalse

M_valuefalse = Falsevalue

M_type = source. Columns (Rnum). DataType

End Sub

Public Sub New (ByVal source as DataTable, ByVal rname As String, ByVal displaytrue as String, ByVal TrueValue As String, _

ByVal Displayfalse As String, ByVal Falsevalue as String)

Rname = Rname

M_displaytrue = Displaytrue

M_valuetrue = TrueValue

M_displayfalse = Displayfalse

M_valuefalse = Falsevalue

M_type = source. Columns (Rname). GetType

End Sub

Private m_displaytrue as String ' the truth displayed

False value displayed by Private M_displayfalse as String '

Private m_valuefalse as String ' stored false value

The true value of the Private m_valuetrue as String ' Store

'-------------the following content to manipulate the display of data---------------

' Rewrite the procedure to display the data in the appropriate form (★)

Protected Overrides Function Getcolumnvalueatrow (ByVal source as System.Windows.Forms.CurrencyManager, ByVal rownum as Integer) as Object

' Get the data from the data source for the specified row (note: The type used here is Object)

Dim result as Object = Mybase.getcolumnvalueatrow (source, rownum)

' Display of settings

If result.tostring = M_valuetrue Then

Return me.m_displaytrue

ElseIf result.tostring = M_valuefalse Then

Return Me.m_displayfalse

ElseIf result is DBNull.Value Then

If Me.nulltext is nothing Then

Return DBNull.Value

Else

Return Me.nulltext

End If

Else

Throw New Exception ("There are characters in this column that do not have a specified display!") ")

End If

End Function

'---------------The following actions update------------------

Private isediting as Boolean = False ' is in the modified state

Private oldvalue as Object ' original value

' Click on the cell, Ready to edit (★)

Protected Overloads Overrides Sub Edit (ByVal source as System.Windows.Forms.CurrencyManager, ByVal rownum as Integer, Byva L bounds as System.Drawing.Rectangle, ByVal [readOnly] as Boolean, ByVal Instanttext as String, ByVal cellisvisible as Boo Lean

Console.WriteLine ("Edit") '---------

' Directly triggers the parent-class event to achieve the effect of clicking on the selected text. (If you don't trigger, move the textbox to the corresponding border)

Mybase.edit (source, rownum, bounds, [readOnly], Instanttext, cellisvisible)

' Set Modify code

isediting = True

' Record original value

OldValue = Me.getcolumnvalueatrow (source, rownum)

End Sub

' Submit changes to the input (★)

Protected Overrides Function Commit (ByVal dataSource as System.Windows.Forms.CurrencyManager, ByVal rownum as Integer) as Boolean

Console.WriteLine ("In Commit") '---------

' If the modification code is true it means that the modification is complete

If not isediting Then return True

' Get the contents of a cell

Dim CurrentValue as Object = Me.TextBox.Text

Console.WriteLine (currentvalue) '---------

Try

CurrentValue = Setsuitablevalue (CurrentValue)

Setcolumnvalueatrow (DataSource, rownum, CurrentValue)

Catch ex as Exception

Return False

End Try

isediting = False

Invalidate ()

Console.WriteLine ("Out Commit") '---------

Return True

End Function

' Abandonment of the processing

Protected Overrides Sub Abort (ByVal rownum as Integer)

Console.WriteLine ("Abort")

isediting = False

Me.TextBox.Text = OldValue

Me.invalidate ()

End Sub

' Display type conversion function

Private Function Getchangetype (ByVal s as String) as Object

Select case M_type. Tostring

Case "System.integer"

Console.WriteLine ("Integer")

return Convert.ToInt32 (s)

Case "System.Boolean"

Console.WriteLine ("Boolean")

return Convert.toboolean (s)

Case "System.String"

return s

Case "System.Decimal"

return Convert.todecimal (s)

End Select

End Function

Private Function Setsuitablevalue (ByVal s as String) as Object

If s = Me.nulltext Then

Return DBNull.Value

ElseIf s = m_displaytrue Then

Return Getchangetype (M_valuetrue)

ElseIf s = M_displayfalse Then

Return Getchangetype (M_valuefalse)

Else

Throw New Exception ("Enter illegal, check the value you are ready to commit after entering!") ")

End If

End Function

End Class