I'm using a DataGridView to load data from a DataTable. This DataGridView is located on a tab (Forms.TabPage). When clicking this tab the datagrid takes a second or two to draw from the top down, regardless of wheather data is being loaded or not.
Is there anything I can do to speed up the Drawing\Rendering when clicking the Tab?
I Don't think the actual population of the DGV is causing this, as it's filled during form load so by the time the tabs click it would have loaded the few rows (20 - 30) it displays.
Using cn As New SqlConnection(connectionString)
Using cmd As SqlCommand = cn.CreateCommand()
cmd.CommandType = System.Data.CommandType.Text
cmd.CommandText = _
" SELECT [finish_time], [file_name], [transfer_status]" & _
" FROM dbo.[transfer_log]"
cmd.Notification = Nothing
cn.Open()
Dim columnSpec = New DataColumn()
With columnSpec
.DataType = GetType(System.String)
.ColumnName = "ClmFinishTime"
End With
Datatable1.Columns.Add(columnSpec)
Dim columnSpec2 = New DataColumn()
With columnSpec2
.DataType = GetType(System.String)
.ColumnName = "ClmFilename"
End With
Datatable1.Columns.Add(columnSpec2)
Dim columnSpec3 = New DataColumn()
With columnSpec3
.DataType = GetType(System.Byte())
.ColumnName = "ClmStatus"
End With
Datatable1.Columns.Add(columnSpec3)
Using dr As SqlDataReader = cmd.ExecuteReader()
While dr.Read()
Dim row As DataRow = Datatable1.NewRow
row("ClmFinishTime") = dr.Item("finish_time")
row("ClmFilename") = dr.Item("file_name")
Select Case dr.Item("transfer_status")
Case 0
row("ClmStatus") = ConvertToByte(My.Resources.accept)
Case 1
row("ClmStatus") = ConvertToByte(My.Resources.remove)
End Select
Datatable1.Rows.Add(row)
End While
End Using
End Using
DataGridView2.AutoGenerateColumns = False
DataGridView2.DataSource = Datatable1
I fixed this by double buffering the control:
Public Shared Sub SetDoubleBuffered(ByVal control As Control)
GetType(Control).InvokeMember("DoubleBuffered", BindingFlags.SetProperty Or BindingFlags.Instance Or BindingFlags.NonPublic, Nothing, control, New Object() {True})
End Sub
My two cents on this. I had a DGV that was extremely slow, even with only 100 records. Running the query wasn't the issue -- it returned results in milliseconds.
I tried the various 'doublebuffer' techniques, to no avail.
With my DGV on a TabControl, I was thinking there was possibly an issue with TabControls + DGVs.
To troubleshoot this, I created a new form, added a DGV, and had it populate the DGV on the form load event. I was quite happy to see the data loaded instantly.
I then started going through each property I had set on my original DGV, changing only one at a time, then opening the form. The DGV loaded instantly, until I set the RowHeadersWidthSizeMode. The default setting for this is 'EnableResizing', whereas my original, slow DGV had been changed to 'AutoSizeToAllHeaders'.
vs.
Sure enough, setting this back to the default of 'EnableResizing' resolved my slow DGV issue. I'm able to reproduce this side-by-side. Leave the DGV # 'EnableResizing', DGV loads instantly. Change it to 'AutoSizeToAllHeaders' and it takes 1-2 seconds before the DGV loads.
Just thought I'd share my experience with this.
Alternatively to #madlan simply set the DoubleBuffered property in the constructor by inheriting the control.
public class DoubleBufferedDataGridView : DataGridView
{
public DoubleBufferedDataGridView() : base()
{
this.DoubleBuffered = true;
}
}
I had a similar problem due to placing the DataGridView object into a TableLayoutPanel. The default behavior in Visual Studio of a TableLayoutPanel has the following property:
Focus -> CausesValidation = True
Due to this, it was taking up to 10 minutes to populate the DataGridView from a large DataTable.
In the Forms Designer, I set this value to
Focus -> CausesValidation = False
My DataGridView now works properly, it redraws in a second or less, and its data source is linked to a DataTable containing 2,000 rows and 100 columns, some cells holding text of up to 32,767 characters. Its response to the user editing cells etc. has no apparent delay.
Related
I have two forms which are connected, the first one has a datagridview(DGV) that will show list of staff.
When I double click the row the data from the FGV will transfer into second form for user to edit the data. Each column from the DGV will insert at textbox combobox etc.
But the combobox on second form are using database when I double click the DGV; the others is fine but for combobox it will show the first data in database.
This is the code for the double click on the first form:
Private Sub DataGridView1_CellDoubleClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellDoubleClick
Dim frmEdit As New Edit
frmEdit.lblEENo.Text = DataGridView1.CurrentRow.Cells(1).Value.ToString
frmEdit.txtName.Text = DataGridView1.CurrentRow.Cells(2).Value.ToString
frmEdit.txtAge.Text = DataGridView1.CurrentRow.Cells(3).Value.ToString
frmEdit.lblAgeCategory.Text = DataGridView1.CurrentRow.Cells(4).Value.ToString
frmEdit.txtGender.Text = DataGridView1.CurrentRow.Cells(5).Value.ToString
frmEdit.cbEthnicity.Text = DataGridView1.CurrentRow.Cells(6).Value.ToString
frmEdit.cbGrade.Text = DataGridView1.CurrentRow.Cells(7).Value.ToString
frmEdit.cbCategory.Text = DataGridView1.CurrentRow.Cells(8).Value.ToString
frmEdit.cbDepartment.Text = DataGridView1.CurrentRow.Cells(9).Value.ToString
frmEdit.cbPosition.Text = DataGridView1.CurrentRow.Cells(10).Value.ToString
frmEdit.txtReporting.Text = DataGridView1.CurrentRow.Cells(11).Value.ToString
frmEdit.DateTimePicker1.Value = DataGridView1.CurrentRow.Cells(12).Value.ToString
frmEdit.DateTimePicker2.Value = DataGridView1.CurrentRow.Cells(13).Value.ToString
If DataGridView1.CurrentRow.Cells(14).Value.ToString = "Y" Then
frmEdit.rbYes.Checked = True
ElseIf DataGridView1.CurrentRow.Cells(14).Value.ToString = "N" Then
frmEdit.rbNo.Checked = True
End If
frmEdit.cbStatus.Text = DataGridView1.CurrentRow.Cells(15).Value.ToString
frmEdit.txtNote.Text = DataGridView1.CurrentRow.Cells(16).Value.ToString
frmEdit.lblMody.Text = tslblLoginAs.Text
frmEdit.ShowDialog()
load_data()
End Sub
This is second form's code for connecting to the database table for the combobox:
Private Sub Edit_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim frmMasterList As New MasterStaff
Dim poscmd As New SqlCommand("SELECT * from MasterPositionList", conn)
Dim posadapt As New SqlDataAdapter(poscmd)
Dim postable As New DataTable
posadapt.Fill(postable)
cbPosition.DataSource = postable
cbPosition.DisplayMember = "PositionName"
Dim depcmd As New SqlCommand("SELECT * from MasterDepartmentList", conn)
Dim depadapt As New SqlDataAdapter(depcmd)
Dim deptable As New DataTable
depadapt.Fill(deptable)
cbDepartment.DataSource = deptable
cbDepartment.DisplayMember = "DeparmentName"
End Sub
The form load event fires too late to populate the combobox. The event is raised almost immediately when you create the form instance in the DataGridView1_CellDoubleClick() method, but the event handler can't actually run until control is returned to the messaging loop, and there's no chance for that to happen until the frmEdit.ShowDialog() line, which is after you have set the combobox values. Therefore the Load event runs after you have populated your desired value and will overwrite that work.
To fix this, move that Load code to the constructor, just after the InitializeComponent() method.
Additionally, since you want to select from the items provided by the database you should look at using the SelectedItem or SelectedValue property, instead of the Text property.
Finally, it's really poor practice to reuse the same connection object throughout an application or form. Yes, database connections are expensive objects to create and manage, but the ADO.Net library already handles this for you. The SqlConnection object you work with in code is a light-weight wrapper over a pool of the more-expensive actual raw connections. When you try to reuse one SqlConnection, you gain efficiency in the cheap thing while losing efficiency in the more expensive thing.
Instead, create (and promptly Dispose()!) a new SqlConnection object every time you need to use the database, and think about reducing connections by reducing round-trips to the database. In this case, you can combine the two SELECT statements into a single string and fill two DataTables in the same database trip:
Private Sub New ' Replaces the current Edit_Load() method
InitializeComponent()
Dim results As New DataSet
'Using block will make sure the connection is closed, **even if an exception is thrown**
' Do NOT(!) try to reuse the connection. Only reuse the connection string.
Using conn As New SqlConnection(connString), _
' Two SELECT queries in one string
cmd As New SqlCommand("SELECT * from MasterPositionList;SELECT * from MasterDepartmentList", conn), _
da As New DataAdapter(cmd)
da.Fill(results)
End Using 'Dispose the database objects as quickly as possible
cbPosition.DisplayMember = "PositionName"
cbDepartment.DisplayMember = "DeparmentName"
cbPosition.DataSource = results.Tables(0) 'Filled two tables in one database call
cbDepartment.DataSource = results.Tables(1)
End Sub
I am wondering why you need a separate form when you could edit the data directly in the DGV. When you think of it, all the data you're trying to edit is already found in the DGV (or should exist in its datasource). You can even have combo boxes inside the DGV, with their own bound datatables. Here is an example that shows how it could be done.
In Edit_Load there is unnecessary repetition. You load the same dataset twice. You could reuse it or even load it at startup and keep it in cache if it's not changing during application runtime.
Plus, rather than fetch values from the DGV, it would better to fetch the selected datarow instead. For this you just need the record ID...
There is no need to access UI attributes, use the underlying datatable instead.
You shouldn't be using index numbers. Imagine the mess and potential for bugs if you want to insert columns or move columns. Also, the user probably can reorder columns in the DGV by drag & drop... thus your logic is ruined and the program will not behave like it should.
Anyway, to answer your issue: you've loaded a datatable, now all you have to do is bind it to the combo (which you did). You have used the DataSource and DisplayMember attributes. You could use SelectedValue to preselect a value in the list like this:
With cbPosition
.DisplayMember = "PositionName"
.ValueMember = "PositionName"
.SelectedValue = "The text value that comes from the DGV"
.DataSource = postable
End With
As long as the value from the DGV is present in the datatable this should work.
Again, I think you should simplify your UI. All the data could be edited in-place in the DGV.
VB.net app changes values in a datagridview programmatically. The values are all as they should be, but the save routine (dtShipments is the datatable that is the source for the datagridview)
Dim dtChanges As DataTable = dtShipments.getchanges()
If more than one has changed, dtChanges is always missing the last row.
In the routine that changes the cell values, I have tried DatagridView1.EndEdit and DatagridView1.CommitEdit, but the behavior is the same. I even tried adding a SendKeys.Send(vbTab) line, since hitting the tab key when making the changes manually is enough to get all the changes to show up in .GetChanges.
What am I missing?
code per request:
Private Sub btnAssign_Click(sender As Object, e As EventArgs) Handles btnAssign.Click
strModErr = "Form1_btnAssign_Click"
Dim sTruck As String = ""
Try
sTruck = Me.DataGridView2.SelectedCells(0).Value.ToString
For Each row As DataGridViewRow In DataGridView1.SelectedRows
row.Cells("Truck").Value = sTruck
Next
DataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit)
Catch ex As Exception
WriteErrorToLog(Err.Number, strModErr + " - " + Err.Description)
End Try
End Sub
Private Function SaveChanges() As Boolean
strModErr = "Form1_SaveChanges"
Dim Conn As New SqlConnection(My.Settings.SQLConnectionString)
Dim sSQL As String = "UPDATE fs_Shipments SET Truck = #Truck, Stop = #Stop WHERE SalesOrder = #SO"
Dim cmd As New SqlCommand(sSQL, Conn)
Dim sSO, sTruck As String
Dim iStop As Integer = 0
Try
DataGridView1.EndEdit()
DataGridView1.ClearSelection()
Dim dtChanges As DataTable = dtShipments.getchanges() 'DataRowState.Modified
If Not dtChanges Is Nothing Then
Conn.Open()
For Each row As DataRow In dtChanges.Rows
sSO = row("SalesOrder").ToString
sTruck = row("Truck").ToString
iStop = CInt(row("Stop").ToString)
With cmd.Parameters
.Clear()
.AddWithValue("#SO", sSO)
.AddWithValue("#Truck", sTruck)
.AddWithValue("#Stop", iStop)
End With
cmd.ExecuteNonQuery()
Next
End If
Return True
Catch ex As Exception
WriteErrorToLog(Err.Number, strModErr + " - " + Err.Description)
Return False
End Try
End Function
I am not exactly 100% sure why this happens. The problem appears to be specific to when the user “selects” the cells in the first grid, and then calls the SaveChanges code “BEFORE” the user has made another selection in the first grid. In other words, if the user “selects” the rows to “assign” the truck to in grid 1, then, “AFTER” the “selected” cells have been filled with the selected truck, THEN, the user selects some other cell in grid 1, THEN calls the save changes code. In that case the code works as expected.
All my attempts at committing the changes, either failed or introduced other issues. I am confident a lot of this has to do with the grids SelectedRows collection. IMHO, this looks like a risky way to set the cell values, I would think a more user-friendly approach may be to add a check box on each row and assign the truck values to the rows that are checked. But this is an opinion.
Anyway, after multiple attempts, the solution I came up with only further demonstrates why using a BindingSource is useful in many ways. In this case, it appears the DataTable is not getting updated with the last cell change. Again, I am not sure “why” this is, however since it appears to work using a BindingSource, I can only assume it has something to do with the DataTable itself. In other words, before the “Save” code is executed, we could call the tables AcceptChanges method, but then we would lose those changes. So that is not an option.
To help, below is a full (no-fluff) example. In the future, I highly recommend you pull out the parts of the code that do NOT pertain to the question. Example, all the code that saves the changes to the DB is superfluous in relation to the question… so remove it. The more unnecessary code you add to your question only increases the number of SO users that will “ignore” the question. If you post minimal, complete and working code that reproduces the problem so that users can simply copy and paste without having to add addition code or remove unnecessary code will increase you chances of getting a good answer. Just a heads up for the future.
The solution below simply adds a BindingSource. The BindingSource’s DataSource is the DataTable dtShipments then the BindingSource is used a DataSource to DataGridView1. Then in the SaveChanges method, “before” the code calls the dtShipment.GetChanges() method, we will call the BindingSources.ResetBinding() method which should complete the edits to the underlying data source, in this case the DataTable dtShipments.
If you create a new VS-VB winforms solution, drop two (2) grids and two (2) buttons onto the form as shown below, then change the button names to “btnAssign” and “btnApplyChanges.” The assign button will add the selected truck in grid two to the selected rows in grid one. The apply changes button simply resets the binding source and displays a message box with the number of rows that were changed in the dtShipments DataTable. It should be noted, that the code calls the dtShipments.AcceptChanges() method to clear the changes. Otherwise, the code will update changes that have already been made.
Dim dtShipments As DataTable
Dim dtTrucks As DataTable
Dim shipBS As BindingSource
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
dtShipments = GetShipmentsDT()
shipBS = New BindingSource()
shipBS.DataSource = dtShipments
dtTrucks = GetTrucksDT()
dtShipments.AcceptChanges()
DataGridView1.DataSource = shipBS
DataGridView2.DataSource = dtTrucks
End Sub
Private Function GetShipmentsDT() As DataTable
Dim dt = New DataTable()
dt.Columns.Add("ID", GetType(String))
dt.Columns.Add("Truck", GetType(String))
dt.Rows.Add(1)
dt.Rows.Add(2)
dt.Rows.Add(3)
dt.Rows.Add(4)
Return dt
End Function
Private Function GetTrucksDT() As DataTable
Dim dt = New DataTable()
dt.Columns.Add("Truck", GetType(String))
For index = 1 To 10
dt.Rows.Add("Truck" + index.ToString())
Next
Return dt
End Function
Private Sub btnAssign_Click(sender As Object, e As EventArgs) Handles btnAssign.Click
Dim sTruck = DataGridView2.SelectedCells(0).Value.ToString
'Dim drv As DataRowView
For Each row As DataGridViewRow In DataGridView1.SelectedRows
'drv = row.DataBoundItem
'drv("Truck") = sTruck
row.Cells("Truck").Value = sTruck
Next
'DataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit)
'shipBS.ResetBindings(True)
'DataGridView1.CurrentCell = DataGridView1.Rows(0).Cells(0)
End Sub
Private Function SaveChanges() As Boolean
Try
shipBS.ResetBindings(True)
Dim dtChanges As DataTable = dtShipments.GetChanges()
If (dtChanges IsNot Nothing) Then
MessageBox.Show("There are " & dtChanges.Rows.Count & " rows changed in the data table")
' update sql DB
dtShipments.AcceptChanges()
End If
Return True
Catch ex As Exception
Return False
End Try
End Function
Private Sub btnApplyChanges_Click(sender As Object, e As EventArgs) Handles btnApplyChanges.Click
Dim ChangesMade As Boolean
ChangesMade = SaveChanges()
End Sub
Lastly, since you are using VB… I highly recommend that you set the “Strict” option to “ON.” When this option is ON, it will flag possible errors that you may be missing. To do this for all future VB solutions, open VS, close any solutions that may be open, then go to Tools->Options->Projects and Solutions->VB Defaults, then set “Option Strict” to “On.” The default setting is off.
I hope this makes sense and helps.
When creating a datagridview in VB.net I cannot get at the cells from anywhere except the Sub where it was made.
I tried placing the code in Form_Load and tried make the Sub Public.
I use Controls.Find, which finds the datagridview, but I cannot access any rows or cells. I can create textbox and label controls and access their text content from anywhere, but not so with the datagridview. This is odd to me.
Using and learning Visual Basic in Visual Studio 2017, for use in my own home business utility.
Dim dgv As New DataGridView
dgv.Location = New Point(2, 200)
dgv.Size = New Size(300, 50)
dgv.Name = "NewDGV"
Dim ColumnTitles() As String = {"ProdId", "Price"}
Dim ColumnWidths() As Integer = {50, 50)
For i = 0 To UBound(ColumnTitles)
Dim col As New DataGridViewTextBoxColumn
col.DataPropertyName = ColumnTitles(i)
col.HeaderText = ColumnTitles(i)
col.Name = ColumnTitles(i)
col.Width = ColumnWidths(i)
dgv.Columns.Add(col)
Next
Controls.Add(dgv)
‘the following sees the datagridview just fine
‘within the same sub
Dim x = dgv.Rows(0).Cells(0).Value
This is how I am creating this control. Perhaps I am Adding to Controls in the wrong way? I am open to better ways to do this.
Dim dgv As DataGridView = CType(Controls("NewDGV"), DataGridView)
dgv.Rows(0).Cells(0).Value = "I found you!"
What this does is find the first Control in the Controls collection, coerces it into a DataGridView type, and assigns it to the variable dgv. You can than manipulate dgv. In this case I put some text in the first cell on the first row.
You could ask the control collection for the instance of your datagridview
Dim MyDgv As DataGridView = Controls.Cast(Of DataGridView).First(Function(dgv) dgv.Name = "NewDGV")
Then work with "MyDGV" properties, methods, and/or events
I am trying to show a DataGridView in a form that is bound to a DataTable, but it's not showing up. I was doing this using a C1TrueDBGrid and that was working...I decided to switch to using a DataGridView due to some complications with the TrueDBGrid. Can anyone help me figure out why nothing is showing?
In the form I declare these:
Public binData As DataSet
Friend WithEvents dgvData As System.Windows.Forms.DataGridView
The binData is filled with tables created via a separate calculation routine. Then this is the form load event:
'create a tab page and add data grid view for every table in the set
For i = 0 To binData.Tables.Count - 1
Dim tabPage As C1.Win.C1Command.C1DockingTabPage = New C1.Win.C1Command.C1DockingTabPage
tabPage.Text = binData.Tables(i).TableName
tabContent.TabPages.Add(tabPage)
Dim dgvData = New System.Windows.Forms.DataGridView
Dim binding As New BindingSource
binding.DataSource = binData.Tables(i)
With dgvData
.Dock = DockStyle.Fill
.AllowUserToOrderColumns = False
.AllowUserToAddRows = False
.AllowUserToDeleteRows = False
.DefaultCellStyle.Alignment = DataGridViewContentAlignment.BottomLeft
.DataSource = binding
.AutoGenerateColumns = True
End With
tabPage.Controls.Add(dgvData)
Next 'DataTable In binData.Tables
When the form loads, the tab pages are there and labeled as expected, but they look empty (no table).
I did try instead setting the DataSource to the DataSet called binData (as opposed to a specific table), and then setting dgvData's DataMember property to the name of the specific table I want to display in it...that made no difference.
Note: I need to be able to do this programmatically at runtime as opposed to using the visual designer because I do not know the exact number of grids I need until the form loads with a particular dataset - the dataset it gets can have a different number of tables depending on what the user wants.
Here's some rough code to add dgvs to a flow panel:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Static dgvCount As Integer
dgvCount += 1
Dim dgvNew As New DataGridView
dgvNew.Width = DataGridView1.Width
dgvNew.Height = DataGridView1.Height
dgvNew.Name = "dgv" & dgvCount
' clone other properties as need
FlowLayoutPanel1.Controls.Add(dgvNew)
Debug.Print(FlowLayoutPanel1.Controls(FlowLayoutPanel1.Controls.Count - 1).Name)
End Sub
Starts with one dgv - DataGridView1 as the model for properties. Anchoring is not working in the flow panel so some custom code may be need to change width.
Flow panel doesn't scroll so may not be the best choice - look into TableLayout as a possibility. TabControl is another option.
OK, well it turns out there was nothing wrong with what I was doing. The issue turned out to be in one line of code that has nothing to do with binding the DGV's datasource or anything.
ComponentOne has a control called a ThemeController in which you can set themes for your forms and the controls within. I had a line of code to set the theme for dgvData to my default application theme (which sets visual style and details regarding colors, fonts, etc.). For whatever reason, THAT was rendering my grid non-visible. I will be logging a ticket with them.
Having trouble with a form with both a Datagridview control and a BindingNavigator control.
Initially I had the following code:
BS = New BindingSource(DS, dsTable) ' (earlier code) Dim BS as New BindingSource
BNV1.BindingSource = BS ' A BindingNavigator
DGV1.DataSource = BS ' A DataGridView
Everything worked well but when I inserted a new row it was displayed at the end of the DataGridView's list and I wanted it to show in the correct sequential location.
I found a recommendation in a forum somewhere that suggested using a DataView on the Datatable to solve this issue. I tried it and it worked great - almost.
Here's the new code:
BS = New BindingSource(DS, dsTable)
DV.Table = DS.Tables(dsTable) ' (earlier code) Dim DV as New DataView
DV.Sort = DS.Tables(dsTable).Columns(0).ColumnName
DGV1.DataSource = DV < ---- instead of the BindingSource 'BS'
BNV1.BindingSource = BS
New records were displayed right in the correctly sequenced location - but -
The BindingNavigator did not change as I scrolled the DataGridView. It never reflected the correct record number.
But when you clicked on the BindingNavigator's moveNext, Previous, Start and End arrows it changed the count correctly. Nothing happened in the
DataGridView but it seems like the BindingNavigator was tracking something else behind the scenes. I suppose it was the original table.
Any idea how to get the BindingNavigator sync'd to the DataView? So the DatagridView and BindingNavigator are looking at the same data?
(I know I can solve this by refilling the DataGridView each time but that seems wastefiul in resources.)
Additional Info: Code that actually does the Insert/ADD
Dim NewRow As DataRow = DT.NewRow
modCommonMaint.FillNewRow(NewRow, pnlData, dicFields)
NewRow(CntText + 1) = 0
NewRow(CntText + 2) = NewRow(0).ToString
LastAdd = txtID.Text.ToUpper.Trim
DT.Rows.Add(NewRow)
DGV1.Refresh()
Try
DA.InsertCommand = cmdA
DA.UpdateCommand = cmdU
DA.Update(DS, dsTable)
Catch ex As Exception
Console.WriteLine("Error" & ex.ToString)
Finally
End Try
This is the code that actually does the INSERT/ADD. It does NOT change under either scenario. To change the behavior all I do is swap the lines in the first 2 code blocks of this note.