I've checked for hours but I can't seem to find anything to help.
I want to loop through tables and columns from a dataset and use the column name in a combobox.items.add() line, however the eventual goal is to fill the combobox from the dataset itself possibly in a combobox.datasource line.
The first problem is that I can't get the code correct to setup the combobox control where it allows me to use .items.add("") and in extension .datasource
Error Message = "Object reference not set to an instance of an object"
dstcopt is the dataset from a oledbDataAdapter .fill(dstcopt,"table") line (which returns correct values)
tc_opt is a tab name on a tab control where the comboboxes are
For Each dstable In dstcopt.Tables
For Each dscolumn In dstable.Columns
Dim colName As String = dscolumn.ToString
MsgBox(colName) 'This retuns "aantigen"
Dim cb As ComboBox = Me.tc_opt.Controls("cb_" & colName)
cb.Items.Add(colName)
'cb_aantigen.DataSource = dstcopt.Tables(dstable.ToString)
'cb_aantigen.DisplayMember = "aantigen"
'cb_atarget.DataSource = dstcopt.Tables(dstable.ToString)
'cb_atarget.DisplayMember = "atarget"
Next
Next
The second problem comes when I do it manually (which works) using the exact combobox names cb_aantigen and cb_atarget as seen in the comments.
The problem is that once the form is loaded and the cb's are filled with the correct values, I can't change the value in any single cb individually, when I change one value it changes them all (there is 15 comboboxes in total) I know this is down to using a dataset, but I don't know away to 'unlink them from each other or the dataset'
Not sure if I need to split this into 2 questions, but help on either problem would be appreciated.
EDIT:
After looking at only this section of code for a day. This is what I have come up with to tackle both the problems at once.
The combobox control not working was down to using a tab tc_opt instead of a groupbox gp_anti
The issue with splitting the dataset up into individual comboboxes, I've worked around by taking the value of each cell in the database and adding it separately, probably a better way to do it though
For Each dstable As DataTable In dstcopt.Tables
For Each dscolumn As DataColumn In dstable.Columns
Dim colName As String = dscolumn.ToString
Dim cb(2) As ComboBox
cb(0) = CType(Me.gp_anti.Controls("cb_" & colName), ComboBox)
cb(1) = CType(Me.gp_rec.Controls("cb_" & colName), ComboBox)
cb(2) = CType(Me.gp_nat.Controls("cb_" & colName), ComboBox)
For icb = 0 To cb.Count - 1
If Not (IsNothing(cb(icb))) Then
For irow = 0 To dstable.Rows.Count - 1
If dstable.Rows(irow)(colName).ToString <> Nothing Then
Dim icbitemdupe As Boolean = False
If cb(icb).Items.Contains(dstable.Rows(irow)(colName).ToString) Then
icbitemdupe = True
End If
If icbitemdupe = False Then
cb(icb).Items.Add(dstable.Rows(irow)(colName).ToString)
End If
End If
Next
End If
Next
Next
Next
Related
I'm trying to convert the first column from a Data Grid View to a list of string, then search through the list and highlight the corresponding row in red.
This is what I currently have
Dim search As String = txtsearch.Text
Dim lsttitlesort As New List(Of String)()
For i = 0 To dgvbooks.Rows.Count - 1
lsttitlesort.Add(dgvbooks(0, i).Value)
Next
For i As Integer = 1 To lsttitle.Count - 1
If lsttitlesort(i).ToLower.Contains(search.ToLower) Then
dgvbooks.Rows(i).DefaultCellStyle.BackColor = Color.Red
End If
Next
The problem is that when I try to run it, it crashes and displays an error message saying
System.NullReferenceException: 'Object reference not set to an instance of an object.'
I'm new to Data Grid Views: can you explain me how to fix it?
You can search directly on the DataGridView without using a list:
Dim search As String = txtsearch.Text
'iterate through all rows of the DataGridView to search the value.
For Each dgrBook As DataGridViewRow In dgvbooks.Rows
'you can skip the new row at the end (if available).
If dgrBook.IsNewRow Then
Continue For
End If
'check if first column contains the search value.
'if search value found on first column set the background color to red,
'otherwise reset the background to white.
If CStr(dgrBook.Cells(0).Value & "").ToLower.Contains(search.ToLower) Then
dgrBook.DefaultCellStyle.BackColor = Color.Red
Else
dgrBook.DefaultCellStyle.BackColor = Color.White
End If
Next
I have a datagrid view with 10 columns. It includes 2 checkbox columns followed by a combobox and then a number of text boxes for data entry. I do not have a database to load the combobox drop down but I do have a variable with 19 rows. I have tried a number of methods from SO but haven't been able to get this to work correctly so I can load the combobox for the user to select a value.
The code I've been using is like this. I have tried several different ways that are commented out as well...
' Build datagridview row
'
Dim t1 As New DataTable
For Each col As DataGridViewColumn In dgvMultiSelect.Columns
t1.Columns.Add(col.HeaderText)
Next
Dim dgvcb As New DataTable
dgvcb.Columns.Add("RunID", GetType(String))
For el = 0 To sRunID.Length - 1
dgvcb.Columns.Add(sRunID(el))
RunID.Items.Add(sRunID(el))
Next
' RunID.DataSource = dgvcb
' RunID.DataPropertyName = "dgvcb"
' RunID.DataSource = sRunID
' RunID.DataPropertyName = "sRunID"
'Dim chk As New DataGridViewCheckBoxColumn()
'DataGridView1.Columns.Add(chk)
'chk.HeaderText = "Check Data"
'chk.Name = "chk"
dgvMultiSelect.Rows(0).Cells(0).Value = True
The checkbox works fine (it shows as checked) and I was able to set the combobox value to show but clicking on the dropdown does nothing. I believe the data is in RunID (the column in the dgv.
Well, the answer that worked for me is: I was referencing the datagridviewCOLUMN and not a datagridviewCOMBOBOXcolumn. Thanks to Sai Kalyan Kumar Akshinthala!
' Build datagridview row
Dim dgvcc As DataGridViewComboBoxColumn
dgvcc = dgvMultiSelect.Columns("RunID")
For el = 0 To sRunID.Length - 1
dgvcc.Items.Add(sRunID(el))
dgvMultiSelect.Rows(0).Cells(2).Value = sRunID(el)
Next
Maybe next time you'll try to understand before voting down. Such a silly thing this voting down anyway. It should not reduce reputation.
Update 5/21/17. Thank you for the suggestion of using a Table. That was helpful. I actually figured it out. I made myinputable a global variable by declaring the Dim statement at the top and making it a Datagridview type. Now I can turn it off in the other event that I needed to do it.
I am a novice. I have created a Datagridview in VB 2015 to capture a bunch of data from the use. When the user is finished with the data entry, I want to store the cell values in my variables. I do not know how to capture any event from my dynamically created datagridview "myinputable." My code is below. Please help.
Private Sub inputmodel()
Dim prompt As String
Dim k As Integer
'
' first get the problem title and the number of objectives and alternatives
'
prompt = "Enter problem title: "
title = InputBox(prompt)
prompt = "Enter number of criteria: "
nobj = InputBox(prompt)
prompt = "Enter number of alternatives: "
nalt = InputBox(prompt)
'
' now create the table
'
Dim Myinputable As New DataGridView
Dim combocol As New DataGridViewComboBoxColumn
combocol.Items.AddRange("Increasing", "Decreaing", "Threashold")
For k = 1 To 6
If k <> 2 Then
Dim nc As New DataGridViewTextBoxColumn
nc.Name = ""
Myinputable.Columns.Add(nc)
Else
Myinputable.Columns.AddRange(combocol)
End If
Next k
' now add the rows and place the spreadsheet on the form
Myinputable.Rows.Add(nobj - 1)
Myinputable.Location = New Point(25, 50)
Myinputable.AutoSize = True
Me.Controls.Add(Myinputable)
FlowLayoutPanel1.Visible = True
Myinputable.Columns(0).Name = "Name"
Myinputable.Columns(0).HeaderText = "Name"
Myinputable.Columns(1).Name = "Type"
Myinputable.Columns(1).HeaderText = "Type"
Myinputable.Columns(2).Name = "LThresh"
Myinputable.Columns(2).HeaderText = "Lower Threshold"
'Myinputable.Columns(2).ValueType = co
Myinputable.Columns(3).Name = "UThresh"
Myinputable.Columns(3).HeaderText = "Upper Threshold"
Myinputable.Columns(4).Name = "ABMin"
Myinputable.Columns(4).HeaderText = "Abs. Minimum"
Myinputable.Columns(5).Name = "ABMax"
Myinputable.Columns(5).HeaderText = "Abs. Maximum "
Myinputable.Rows(0).Cells(0).Value = "Help"
If Myinputable.Capture = True Then
MsgBox(" damn ")
End If
End Sub
As #Plutonix suggests, you should start by creating a DataTable. Add columns of the appropriate types to the DataTable and then bind it to the grid, i.e. assign it to the DataSource of your grid, e.g.
Dim table As New DataTable
With table.Columns
.Add("ID", GetType(Integer))
.Add("Name", GetType(String))
End With
DataGridView1.DataSource = table
That will automatically add the appropriate columns to the grid if it doesn't already have any, or you can add the columns in the designer and set their DataPropertyName to tell them which DataColumn to bind to. As the user makes changes in the grid, the data will be automatically pushed to the underlying DataTable.
When you're done, you can access the data via the DataTable and even save the lot to a database with a single call to the Update method of a data adapter if you wish.
I have a Part class with the fields list in the code below. I have a DataGridView control, which I am filtering with the Advanced DGV (ADGV) DLL from NUGET. I must include the ADGV in my winform. I currently have a DataGridView, a search box on the form, and a button to run the following function. I need to go through all of the visible rows, collect a unique list of part numbers with their most recent revisions, and then color the rows in DataGridView which are out of date by checking the part number and rev on each row against the mostuptodate list. For 45,000 entries displayed in DataGridView, this take ~17 secs. For ~50 entries, it take ~1.2 seconds. This is extremely inefficient, but I can't see a way to cut the time down.
Sub highlightOutdatedParts()
'Purpose: use the results in the datagridview control, find the most recent revision of each part, and
' highlight all outdated parts relative to their respective most recent revisions
'SORT BY PART NUMBER AND THEN BY REV
If resultsGrid.ColumnCount = 0 Or resultsGrid.RowCount = 0 Then Exit Sub
Dim stopwatch As New Stopwatch
stopwatch.Start()
resultsGrid.Sort(resultsGrid.Columns("PartNumber"), ListSortDirection.Ascending)
Dim iBag As New ConcurrentBag(Of Part)
Dim sortedList As Generic.List(Of Part)
For Each row As DataGridViewRow In resultsGrid.Rows
If row.Visible = True Then
Dim iPart As New Part()
Try
iPart.Row = row.Cells(0).Value
iPart.Workbook = CStr(row.Cells(1).Value)
iPart.Worksheet = CStr(row.Cells(2).Value)
iPart.Product = CStr(row.Cells(3).Value)
iPart.PartNumber = CStr(row.Cells(4).Value)
iPart.ItemNo = CStr(row.Cells(5).Value)
iPart.Rev = CStr(row.Cells(6).Value)
iPart.Description = CStr(row.Cells(7).Value)
iPart.Units = CStr(row.Cells(8).Value)
iPart.Type = CStr(row.Cells(9).Value)
iPart.PurchCtgy = CStr(row.Cells(10).Value)
iPart.Qty = CDbl(row.Cells(11).Value)
iPart.TtlPerProd = CDbl(row.Cells(12).Value)
iPart.Hierarchy = CStr(row.Cells(13).Value)
iBag.Add(iPart)
Catch ice As InvalidCastException
Catch nre As NullReferenceException
End Try
End If
Next
sortedList = (From c In iBag Order By c.PartNumber, c.Rev).ToList() ' sort and convert to list
Dim mostUTDRevList As New Generic.List(Of Part) ' list of most up to date parts, by Rev letter
For sl As Integer = sortedList.Count - 1 To 0 Step -1 'start at end of list and work to beginning
Dim query = From entry In mostUTDRevList ' check if part number already exists in most up to date list
Where entry.PartNumber = sortedList(sl).PartNumber
Select entry
If query.Count = 0 Then ' if this part does not already exist in the list, add.
mostUTDRevList.Add(sortedList(sl))
End If
Next
'HIGHLIGHT DATAGRIDVIEW ROWS WHERE PART NUMBERS ARE OUT OF DATE
For Each row As DataGridViewRow In resultsGrid.Rows
' if that part with that Rev does not exist in the list, it must be out of date
Try
Dim rowPN As String = CStr(row.Cells(4).Value).ToUpper ' get part number
Dim rowR As String = CStr(row.Cells(6).Value).ToUpper ' get Rev
Dim query = From entry In mostUTDRevList ' check if that part number with that Rev is in the list.
Where entry.PartNumber.ToUpper.Equals(rowPN) AndAlso
entry.Rev.ToUpper.Equals(rowR)
Select entry
If query.Count = 0 Then ' if the part is out of date highlight its' row
row.DefaultCellStyle.BackColor = Color.Chocolate
End If
Catch ex As NullReferenceException
Catch ice As InvalidCastException
End Try
Next
resultsGrid.Select()
stopwatch.Stop()
If Not BackgroundWorker1.IsBusy() Then timertextbox.Text = stopwatch.Elapsed.TotalSeconds.ToString & " secs"
MessageBox.Show("Highlighting completed successfully.")
End Sub
It is almost always faster to work with the data than the control. The control is simply the means to present a view of the data (in a grid) to the users. Working with the data from there requires too much converting to be effieicent. Then, use the DGV events to highlight the rows
Its hard to tell all the details of what you are doing, but it looks like you are comparing the data to itself (as opposed to some concrete table where the lastest revision codes are defined). Nor is it clear why the datasources are collections, ConcurrentBags etc. The key would be to use collections optimized for the job.
To demonstrate, I have a table with 75,000 rows; the product codes are randomly selected from a pool of 25,000 and a revision code is a random integer (1-9). After the DGV datasource is built (a DataTable) a LookUp is created from the ProductCode-Revision pair. This is done once and once only:
' form level declaration
Private PRCodes As ILookup(Of String, Int32)
' go thru table
' group by the product code
' create an anon Name-Value object for each,
' storing the code and highest rev number
' convert result to a LookUp
PRCodes = dtSample.AsEnumerable.
GroupBy(Function(g) g.Item("ProductCode"),
Function(key, values) New With {.Name = key.ToString(), .Value = values.
Max(Of Int32)(Function(j) j.Field(Of Int32)("RevCode"))
}).
ToLookup(Of String, Int32)(Function(k) k.Name, Function(v) v.Value)
Elapsed time via stopwatch: 81 milliseconds to create the collection of 23731 items. The code uses an anonymous type to store a Max Revision code for each product code. A concrete class could also be used. If you're worried about mixed casing, use .ToLowerInvariant() when creating the LookUp (not ToUpper -- see What's Wrong With Turkey?) and again later when looking up the max rev.
Then rather than looping thru the DGV rows use the RowPrePaint event:
If e.RowIndex = -1 Then Return
If dgv1.Rows(e.RowIndex).IsNewRow Then Return
' .ToLowerInvariant() if the casing can vary row to row
Dim pc = dgv1.Rows(e.RowIndex).Cells("ProductCode").Value.ToString()
Dim rv = Convert.ToInt32(dgv1.Rows(e.RowIndex).Cells("RevCode").Value)
Dim item = PRCodes(pc)(0)
If item > rv Then
dgv1.Rows(e.RowIndex).DefaultCellStyle.BackColor = Color.MistyRose
End If
Notes
It takes some time to create the DataSource, but 75,000 rows is a lot to throw at a user
The time to create the LookUp is minimal - barely measurable
There is no noticeable wait in displaying them because a) the LookUp is made for this sort of thing, b) rows are done as needed when they are displayed. Row # 19,999 may never be processed if the user never scrolls that far.
This is all geared to just color a row. If you needed to save the Current/NotCurrent state for each row, add a Boolean column to the DataTable and loop on that. The column can be invisible if to hide it from the user.
The random data results in 47,000 out of date RevCodes. Processing 75k rows in the DataTable to set the flag takes 591 milliseconds. You would want to do this before you set the DataTable as the DataSource to prevent changes to the data resulting in various events in the control.
In general, the time to harvest the max RevCode flag and even tag the out of date rows is a trivial increment to creating the datasource.
The Result:
The data view is sorted by ProductCode so that the coloring of lower RevCodes is apparent.
We surely cant grok all the details and constraints of the system from a small snippet - even the data types and original datasource are a guess for us. However, this should provide some help with better look-up methods, and the concept of working with the data rather than the user's view.
One thing is the revision code - yours is treating them as a string. If this is alphanumeric, it may well not compare correctly - "9" sorts/compares higher than "834" or "1JW".
See also:
Lookup(Of TKey, TElement) Class
Anonymous Types
The solution was spurred in part by #Plutonix.
Sub highlightOutdatedParts()
If resultsGrid.ColumnCount = 0 Or resultsGrid.RowCount = 0 Then Exit Sub
Dim stopwatch As New Stopwatch
stopwatch.Start()
resultsGrid.DataSource.DefaultView.Sort = "PartNumber ASC, Rev DESC"
resultsGrid.Update()
'HIGHLIGHT DATAGRIDVIEW ROWS WHERE PART NUMBERS ARE OUT OF DATE
Dim irow As Long = 0
Do While irow <= resultsGrid.RowCount - 2
' if that part with that Rev does not exist in the list, it must be out of date
Dim utdPN As String = resultsGrid.Rows(irow).Cells(4).Value.ToString().ToUpper()
Dim utdRev As String = resultsGrid.Rows(irow).Cells(6).Value.ToString().ToUpper()
Dim iirow As Long = irow + 1
'If iirow > resultsGrid.RowCount - 1 Then Exit Do
Dim activePN As String = Nothing
Dim activeRev As String = Nothing
Try
activePN = resultsGrid.Rows(iirow).Cells(4).Value.ToString().ToUpper()
activeRev = resultsGrid.Rows(iirow).Cells(6).Value.ToString().ToUpper()
Catch ex As NullReferenceException
End Try
Do While activePN = utdPN
If iirow > resultsGrid.RowCount - 1 Then Exit Do
If activeRev <> utdRev Then
resultsGrid.Rows(iirow).DefaultCellStyle.BackColor = Color.Chocolate
End If
iirow += 1
Try
activePN = resultsGrid.Rows(iirow).Cells(4).Value.ToString().ToUpper()
activeRev = resultsGrid.Rows(iirow).Cells(6).Value.ToString().ToUpper()
Catch nre As NullReferenceException
Catch aoore As ArgumentOutOfRangeException
End Try
Loop
irow = iirow
Loop
resultsGrid.Select()
stopwatch.Stop()
If Not BackgroundWorker1.IsBusy() Then
timertextbox.Text = stopwatch.Elapsed.TotalSeconds.ToString & " secs"
resultcounttextbox.Text = resultsGrid.RowCount - 1 & " results"
End If
MessageBox.Show("Highlighting completed successfully.")
End Sub
I have a table named users which has the following columns in it
User_id,user_name,user_pwd,First_Name,Middle_Name,Last_Name and user_type.
I have dataset named dst and created a table called user in the dataset. Now I want to populate listbox with user_Name, First_Name, Last_name of each and every row in the table user.
I am able to add one column value at a time but not getting how to add multiple column values of each row to listbox
Dim dt As DataTable = Dst.Tables("user")
For Each row As DataRow In dt.Rows
lstUsers.Items.Add(row("User_Name"))
Next
Above code works perfectly but I also want to add First_name as well as last_name to the list box at the same time.
Use same approach as you have, but put all values you want in one string.
Dim dt As DataTable = Dst.Tables("user")
For Each row As DataRow In dt.Rows
Dim sItemTemp as String
sItemTemp = String.Format("{0},{1},{2}", row("User_Name"), row("First_Name"), row("Last_Name"))
lstUsers.Items.Add(sItemTemp)
Next
String.Format() function will call .ToString() on all parameters.
In this case if row(ColumnName) is NULL value then .ToString() return just empty string
You have 2 choices:
Using the ListBox:
To use the ListBox, set the font to one that is fixed width like courier new (so that the columns line up), and add the items like this:
For Each row As DataRow In dt.Rows
lstUsers.Items.Add(RPAD(row("User_Name"),16) & RPAD(row("First_Name"),16) & RPAD(row("Last_Name"),16))
Next
The RPAD function is defined like this:
Function RPAD(a As Object, LENGTH As Object) As String
Dim X As Object
X = Len(a)
If (X >= LENGTH) Then
RPAD = a : Exit Function
End If
RPAD = a & Space(LENGTH - X)
End Function
Adjust the LENGTH argument as desired in your case. Add one more for at least one space. This solution is less than ideal because you have to hard-code the column widths.
Use a DataGridView control instead of a ListBox. This is really the best option, and if you need, you can even have it behave like a ListBox by setting the option to select the full row and setting CellBorderStyle to SingleHorizontal. Define the columns in the designer, but no need to set the widths - the columns can auto-size, and I set that option in the code below. if you still prefer to set the widths, comment out the AutoSizeColumnsMode line.
The code to set up the grid and add the rows goes like this:
g.Rows.Clear() ' some of the below options are also cleared, so we set them again
g.AutoSizeColumnsMode = DataGridViewAutoSizeColumnMode.AllCells
g.CellBorderStyle = DataGridViewCellBorderStyle.SingleHorizontal
g.SelectionMode = DataGridViewSelectionMode.FullRowSelect
g.AllowUserToAddRows = False
g.AllowUserToDeleteRows = False
g.AllowUserToOrderColumns = True
For Each row As DataRow In dt.Rows
g.Rows.Add(row("User_Name"), row("First_Name"), row("Last_Name"))
Next
You might solved your problem by now but other users like me might have issue with it.
Above answers given worked for me even but I found a same answer in a simple way according to what I want..
cmd = New SqlCommand("select User_Name, First_Name, Last_Name from User")
Dim dr As SqlDataReader = cmd.ExecuteReader(YourConnectionString)
If dr.HasRows Then
Do While dr.Read
lst.Items.Add(dr.Item(0).ToString & " " & dr.Item(1).ToString & " " & dr.Item(2).ToString)
Loop
End If
This worked for me, maybe wrong way but I found it simple :)
May I suggest you use a ListView control instead of Listbox?
If you make the switch, here's a sample subroutine you could use to fill it up with the data you said you want. Adapt it the way you like; there's much room for improvement but you get the general idea:
Public Sub FillUserListView(lstUsers As ListView, Dst As DataSet)
Dim columnsWanted As List(Of String) = New List(Of String)({"User_Name", "First_Name", "Last_Name"})
Dim dt As DataTable = Dst.Tables("user")
Dim columns As Integer = 0
Dim totalColumns = 0
Dim rows As Integer = dt.Rows.Count
'Set the column titles
For Each column As DataColumn In dt.Columns
If columnsWanted.Contains(column.ColumnName) Then
lstUsers.Columns.Add(column.ColumnName)
columns = columns + 1
End If
totalColumns = totalColumns + 1
Next
Dim rowObjects(columns - 1) As ListViewItem
Dim actualColumn As Integer = 0
'Load up the rows of actual data into the ListView
For row = 0 To rows - 1
For column = 0 To totalColumns - 1
If columnsWanted.Contains(dt.Columns(column).ColumnName) Then
If actualColumn = 0 Then
rowObjects(row) = New ListViewItem()
rowObjects(row).SubItems(actualColumn).Text = dt.Rows(row).Item(actualColumn)
Else
rowObjects(row).SubItems.Add(dt.Rows(row).Item(actualColumn))
End If
lstUsers.Columns.Item(actualColumn).Width = -2 'Set auto-width
actualColumn = actualColumn + 1
End If
Next
lstUsers.Items.Add(rowObjects(row))
Next
lstUsers.View = View.Details 'Causes each item to appear on a separate line arranged in columns
End Sub