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VB.net 2.0 Windows Forms DataGridView Get Cell Value from Column Name and Row
I'm new to VB.net and for months I have been searching for a way to get the value of a datagridview cell using the ColumnName and the Row. I have been told on this site and several others either that you cannot do it, you can only get the value of a cell by using the cell index, or you can do it simply by referring to the cell by Cells("ColumnName"). After testing these suggestions, neither worked.
This morning a did read another response on this site that was the best presentation on this subject yet but the author did not think you could do it. But I really wanted to be able to get the value of a cell using the column name and the row. Using this article as my starting point, here's what I found
1) You cannot find the cell associated with a DataGridColumn from the DataGridColumn.
2) You cannot refer to a cell by name.
3) There is no ordinal relationship between columns and cells, e.g. if column 2 = cell 8 then column 3 may not point to cell 9.
4) However, you can get the DataGridColumn from a Cell using the OwningColumn property.
At first the Cell.OwningColumn property seems backward but after thinking about it, the OwningColumn is the Foreign Key to DataGridColumn and the DataGridColumn is the parent of the cell (There are many cells in a Column).
Using this, I was able to create the code to generate a SortedList with the ColumnName as the Sort Field, and the Cell Index as the second field. After testing this works greate. I have added the code snippet below. Essentially this code allows you to write formulas based on column names instead of cell index numbers, for example. (This is a simplified snipet that does not include reference to sorted list)
TotalCost = Cost1 + Cost2
I would really appreciate any feedback on the algorithm and the code. I hope this helps others.
PS Can I get some points for answering this question
This morning a did read another response on this site that was the best presentation on this subject yet but the author did not think you could do it. But I really wanted to be able to get the value of a cell using the column name and the row. Using this article as my starting point, here's what I found
1) You cannot find the cell associated with a DataGridColumn from the DataGridColumn.
2) You cannot refer to a cell by name.
3) There is no ordinal relationship between columns and cells, e.g. if column 2 = cell 8 then column 3 may not point to cell 9.
4) However, you can get the DataGridColumn from a Cell using the OwningColumn property.
At first the Cell.OwningColumn property seems backward but after thinking about it, the OwningColumn is the Foreign Key to DataGridColumn and the DataGridColumn is the parent of the cell (There are many cells in a Column).
Using this, I was able to create the code to generate a SortedList with the ColumnName as the Sort Field, and the Cell Index as the second field. After testing this works greate. I have added the code snippet below. Essentially this code allows you to write formulas based on column names instead of cell index numbers, for example. (This is a simplified snipet that does not include reference to sorted list)
TotalCost = Cost1 + Cost2
I would really appreciate any feedback on the algorithm and the code. I hope this helps others.
PS Can I get some points for answering this question
Public dgvCells as New SortedList(Of String, Long)
'-- Load Sorted List when you first enter the DataGrid (Not Datagrid must have rows)
If dgvCells.Count = 0 then
Dim rowCurr as DataGridViewRow = datagridview1.currentrow
Dim strColumnName as string
Dim dgvColumn as New datagridviewcolumn
Dim i as Int16 = 0
For i = 0 to rowCurr.Cells.count -1
dgvColumn = rowCurr.Cells(i).OwningColumn
if dgvColumn.IsDataBound then
strColumnName = dgvColumn.DataPropertyName
Else
strColumnName = dgvColumn.name
End If
dgvCells.Add(strColumnName, i)
Next
End If
'-- Get the Cell Value by ColumnName
Dim rowCurrent as DataGridViewRow = datagridview1.CurrentRow
Dim intColumnIndex as integer = Cint(dgvCells("CompanyName"))
Dim strCompanyName as string = Cstr(rowCurrent.Cells(intColumnIndex).Value)
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I don't know what you've been reading/trying but it looks to me as though you have been solving a problem which doesn't exist.
Open a new project and drag controls onto the default form so it looks like the screenshot below. Leave all the names as the default but alter the dgv's AllowUserToOrderColumns setting to True (so you can experiment with swapping columns around if you wish). Copy the code below into the form. Run it.
Doesn't that do what you want? If so, what is it you want that it doesn't do?
Roger
Open a new project and drag controls onto the default form so it looks like the screenshot below. Leave all the names as the default but alter the dgv's AllowUserToOrderColumns setting to True (so you can experiment with swapping columns around if you wish). Copy the code below into the form. Run it.
Doesn't that do what you want? If so, what is it you want that it doesn't do?
Roger
Public Class Form1
Private dt As New DataTable
Private Sub maketable()
Dim dc0 As New DataColumn("ID", GetType(Integer))
dc0.AutoIncrement = True
dt.Columns.Add(dc0)
Dim dc1 As New DataColumn("Name", GetType(String))
dt.Columns.Add(dc1)
Dim dc2 As New DataColumn("Item", GetType(String))
dt.Columns.Add(dc2)
Dim dc3 As New DataColumn("CompanyName", GetType(String))
dt.Columns.Add(dc3)
For i As Integer = 0 To 5
Dim dr As DataRow = dt.NewRow
dr(1) = "Name" & i.ToString
dr(2) = "Item" & i.ToString
dr(3) = "Company" & i.ToString
dt.Rows.Add(dr)
Next
dt.AcceptChanges()
End Sub
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
maketable() ' get some dummy data
DataGridView1.DataSource = dt
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'get the value from the current row
Dim dgvr As DataGridViewRow = DataGridView1.CurrentRow
If Not dgvr Is Nothing Then
Label1.Text = dgvr.Cells("CompanyName").Value
End If
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
'get the value from the row specified in the textbox
If Not IsNumeric(TextBox1.Text) Then Exit Sub
Dim rowindex As Integer = CInt(TextBox1.Text)
If rowindex > DataGridView1.RowCount Then Exit Sub
Dim dgvr As DataGridViewRow = DataGridView1.Rows(rowindex)
If Not dgvr Is Nothing Then
Label2.Text = dgvr.Cells("CompanyName").Value
End If
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
'get the values from all rows
Dim labeltext As String = ""
For Each dgvr As DataGridViewRow In DataGridView1.Rows
labeltext &= dgvr.Cells("CompanyName").Value & vbCrLf
Next
Label3.Text = labeltext
End Sub
End Class
Thanks for your response. I understand now what has been happening. I have not been defining the underlying table for the DataGridView. I have been creating a DataSourceand setting it as the Data Source for the DataGridView. After reviewing your reponse, I created a new Test project and used the default form form1.vb. I created a datasource using a SQL Server DB and itsContact Table. I then used the Contact table as the DataSource for the DataGridView. I added a button on the form and created the proc:
strContactLF = me.DataGridView1.CurrentRo
It fired the exception
Column named ContactLF cannot be found. Parameter name: columnName
After reviewing your code, I understand how it would work. However as an old Access Developer I'm used to just dragging and dropping controls on forms
Since you generate the table on the form Load and I create the Sorted List on the same event, processing time should be roughly equivalent. Your approach has the benefit that the datatable exists if there are no rows in the DatagridView. My approach does not have that because it is dependent that at least one row in the datagridview exists. However, and for me it's a big however, I can move columns in the Datagrid using the designer and using the Sorted List without modifying the code, the DataGridView Cell Names are automatically reset when the Form is Loaded. The code does not need to be updated and a new revision does not have to be documented. I seem to find clients that want columns moved all the time and automatically reseetting cell names makes more sense to me.
Thanks again.
strContactLF = me.DataGridView1.CurrentRo
It fired the exception
Column named ContactLF cannot be found. Parameter name: columnName
After reviewing your code, I understand how it would work. However as an old Access Developer I'm used to just dragging and dropping controls on forms
Since you generate the table on the form Load and I create the Sorted List on the same event, processing time should be roughly equivalent. Your approach has the benefit that the datatable exists if there are no rows in the DatagridView. My approach does not have that because it is dependent that at least one row in the datagridview exists. However, and for me it's a big however, I can move columns in the Datagrid using the designer and using the Sorted List without modifying the code, the DataGridView Cell Names are automatically reset when the Form is Loaded. The code does not need to be updated and a new revision does not have to be documented. I seem to find clients that want columns moved all the time and automatically reseetting cell names makes more sense to me.
Thanks again.
I spent more time reviewing your response and was wondering if the problem is that I'm using SQL Server as the datasource provider. Does SQL Server provide the Column Names so that they can be used as Cell Index.
I have modified my test so that the code mimicks your code exactly. The only difference seems to be that I'm using SQL Server and you used a local table that you created.
I have modified my test so that the code mimicks your code exactly. The only difference seems to be that I'm using SQL Server and you used a local table that you created.
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.NET Programming
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The .NET Framework is not specific to any one programming language; rather, it includes a library of functions that allows developers to rapidly build applications. Several supported languages include C#, VB.NET, C++ or ASP.NET.