Having set up a datagridview, bound to a bindingsource, I have to use the cellformatting to paint the cells various colours.
Since you cannot access a field or record via bindingsource on a cellformatting event, the only way I could access the data, is through a column such as the primary ID for example. (this is only for cellformatting, i have no problem accessing the ID through the bindignsource.current object).
So, once I have finished designing and testing my datagridview, I then switch various columns (ID) for this example, to visible=false to make the column invisible.
I now cannot access the column data through cellformatting. I have read on a number of pages listed by google that since datagridview doesnt render the columns, the values are unobtainable aside from a couple of alternatives such as :
.TAG
and datakeynames
I cannot find datakeynames under datagridview for winforms for some reason.
.tag doesnt seem to do anything as far as I can tell.
Since trying to use this from the cell formatting, I am unable to use
Select Case .Columns(e.ColumnIndex).DataPropertyName.ToLower
or
If Datagridview1.columns(e.columnindex).datapropertyname.tolower='id' Then
as the column is invisible...
Shame I cannot access the bindingsource through cellformatting, but there must be a way and there must be others who have had this issue.
Use DataBoundItem:
Dim drw As DataRow = DirectCast(DataGridView1.Rows(i).DataBoundItem, DataRowView).Row
(Assuming you've bound to a DataTable)
Related
What I am doing
I am developing a VisualBasic application where the GUI is separated from the data manipulation (frontend and backend). This particular piece of code keeps track of the Serial Numbers already measured and displays them in the Form as a DGV with the serial number and an image or not.
My code
In a class that the GUI Form instantiates, my data is stored in a DataTable with a BindingSource, with the second column displaying an Image when I tell it to in the program (Nothing in the beginning):
Public SerialNumbersBindingSource As New BindingSource
Public SerialNumbersDataTable As New DataTable
(...)
SerialNumbersBindingSource.DataSource = SerialNumbersDataTable
SerialNumbersDataTable.Columns.Add("Serial", Type.GetType("System.String"))
SerialNumbersDataTable.Columns.Add("Pass", MyImage.GetType)
In my GUI Form code, a DataGridView has its DataSource set to the former DataTable:
DataGridViewSerialNumber.DataSource = MyObject.SerialNumbersDataTable
By just updating the DataTable in my class, the DataGridView updates automatically to reflect the current state of it. I do it like:
SerialNumbersDataTable.Add(CurrentSerial, MyImage)
The results I get
The code works, so I can modify and access the DataTable and the DataGridView autoupdates. But the images are not stretching, so I can only see a small part of them.
What I need
I need the second column named "Pass" in DataGridView to stretch the images.
What have I tried
If I access the column, it is treated like a DGVColumn and not a DGVImageColumn, so the Layout operation fails.
DataGridViewSerialNumber.Columns("Pass").DataGridViewImageCellLayout.Stretch
Microsoft's Docs page tells me to do this, which treats the columns like DGVImageColumn as I need "Pass" to. It fails because the first column is a Text one, not image.
For Each column As DataGridViewImageColumn In DataGridViewSerialNumber.Columns("Pass")
column.ImageLayout = DataGridViewImageCellLayout.Stretch
Next
Also I have tried creating a local DGVImageColumn, modify it and write it onto the original column, but it is read-only.
Dim imageColumn As DataGridViewImageColumn
imageColumn = DataGridViewSerialNumber.Columns("Pass")
imageColumn.ImageLayout = DataGridViewImageCellLayout.Stretch
DataGridViewSerialNumber.Columns("Pass") = imageColumn
I have also tried to do it from the designer. If I click the DGV, arrow to the right and 'Edit Column', I can create the two columns and setup Pass as ImageColumn with Stretched Layout. But when I set up DGVSerialNumbers.Datasource to my DataTable, it adds the DataTable's columns to the DGV's.
Failed DGV with columns added in designer
It's time for you to learn how to cast. If you want to access one column then don't use a loop. Simply access the column you want and then cast it as the type you want to use it as. You also need to actually assign the appropriate value to the appropriate property.
DirectCast(DataGridViewSerialNumber.Columns("Pass"), DataGridViewImageColumn).ImageLayout = DataGridViewImageCellLayout.Stretch
If you want to break that up for clarity:
Dim imageColumn = DirectCast(DataGridViewSerialNumber.Columns("Pass"), DataGridViewImageColumn)
imageColumn.ImageLayout = DataGridViewImageCellLayout.Stretch
Also, be aware that Stretch will not retain the original aspect ratio, so you might want to use Zoom instead.
I have set a combobox to be visible in column1 of my Datagridview. Now I'm trying to fill same row of Datagridview where Combobox appears, from Combobox_Key_Down event. This is my code for showing combobox:
Private Sub My_DGV_CellMouseClick(sender As Object, e As DataGridViewCellMouseEventArgs) Handles MY_DGV.CellMouseClick
If e.RowIndex >= 0 Then
With My_DGV
If .Columns(.Rows(e.RowIndex).Cells(e.ColumnIndex).ColumnIndex).Name = "Column1" Then
.CurrentCell = .Rows(.CurrentRow.Index).Cells(.CurrentCell.ColumnIndex)
Show_Combobox(.CurrentRow.Index, .CurrentCell.ColumnIndex) 'function that shows my Combobox in that cells
Combo.Visible = True
Else
Combo.Visible = False
End If
End With
End If
End Sub
I tried many things, but I don't know how to determine in which row Combobox appears and how give that Datagridview row my Combobox values. Someone please give me a clue of what should I do. Thanks in advance !
The first problem with your approach is that the DGV can have only one DataSource: it can either show the m:m association table or the related elements. If you include columns from one of the tables into the query for display, the table becomes non updatable and users can be confused why they cannot edit something they can see. It seems of little value they way you describe it, since they cannot see the detail data until after they make a selection.
Next, it requires another datatable to supply the details for CboColB. Since you want the DGV bound to a DataTable easy updates, you end up having to poke data into cells over and over.
Finally, consider what the user is confronted with. Using a Country table (200+ countries/locales with ISO code and name) and a list of flag colors, a table for CountryFlagColors will have hundreds and hundreds of rows (at just 2 colors per flag).
A better display might be to filter the m:m table (flagcolor) to a selected item so the user is only confronted with the data subset they are currently interested in:
The datatable used in the DGV is built from the m:m table:
The Country column is hidden.
When they choose from the CBO at the top, that is used as a RowFilter to limit the rows to the relevant ones.
In the RowValidating event, when the country cell is DBNull, copy the SelectedValue from the country combo to the DGV cell to fill in the blank
I would probably really make the user click a button and manually add a row so I could seed the country value then rather than depend on events.
It uses a DataAdapter and after adding X number of flag definitions, da.Update(dtFlagColors) applies/saves all the changes.
Ok, so that provides the core functionality to assign N color selections to define the flag colors for a country. The missing element is the 'details' for the Color item.
I added a meaningless int and string item to the Color table, one way to display these would be to create an alias in the SQL with the important details. Displaying them as discrete elements can either make the query non updatable or invites the user to edit things they cannot edit here. My silly SQL:
"SELECT Id, Name, Concat(Name , ' (' , intItem , ' ' , stritem,')') As Info from FColor"
Then use 'Info' as the display member on the CBO column in the dgv:
dc = DirectCast(dgvCF.Columns(0), DataGridViewComboBoxColumn)
dc.DataSource = dtFlagColors
dc.DisplayMember = "info"
dc.ValueMember = "id"
dgvCF.DataSource = dtSample
The combo column has its own datasource of course, in order to display one thing and use another for as the Value to give back to you. Result (the values are silly):
It is not exactly what you want, but comes close and is much simpler. It also requires almost no code for driving the associative entity. Another alternative would be to use a DGV as the second picker so you can show the extended data and manually add rows to a DGV:
If you set the dropdown style to Nothing, it looks like a text column.
I have around 15 comboboxes on my form, all being loaded with the same information pulled from a table(~150 entries). Currently I am taking the information from the table, then looping through the entries and adding them to each textbox. I'm wondering if there's a more efficient way to load these comboboxes then having to individually add the table entry into each combobox, having to list 15 lines of code within the For loop.
I'm not seeing any performance issues with this, but figured I might as well work with the most efficient way possible rather than stick with what works. :)
You can create a list of the combo boxes, and then just loop through them. For instance:
Dim cbos() As ComboBox = {ComboBox1, ComboBox2, ComboBox3}
For Each cbo As ComboBox In cbos
' Load cbo from table
Next
Alternatively, if they are named consistently, you could find the combo box by name:
For i As Integer = 1 to 15
Dim cbo As ComboBox = DirectCast(Controls("ComboBox" & i.ToString())), ComboBox)
' Load cbo from table
Next
Since Combobox items are a collection, if their elements are the same, you can build and array with the objects you want to insert, and then just insert this array to each ComboBox with the method AddRange() (it's a method which exists inside the Combobox.items).
Getting an example from MSDN:
Dim installs() As String = New String() {"Typical", "Compact", "Custom"}
ComboBox1.Items.AddRange(installs)
Then you would only have to do a loop to add the array to each ComboBox. Of course, you will need to build your array first on your own, instead of this easy string array from the example.
Reference:
MSDN - AddRange
You could also do it this way since you mentioned that you already have a table.
Use a datatable
Change your table object into a datatable, which will assist in binding to the comboboxes. It might help if you add the datatable to a dataset too. That way you can attach all ComboBoxes (which are UI elements that let users see information) to the same DataSource, which is the datatable, in the dataset.
Binding
Now all you need to do is loop through all the comboboxes and set the datasource to the same table, that is if you decide to do it programmatically like so:
ComboBox1.DataSource = ds.Tables(0)
ComboBox1.ValueMember = "au_id"
ComboBox1.DisplayMember = "au_lname"
A further tutorial on this with the example above is found here
You can then also get the user selected value with ComboBox1.selectedValue.
On the other hand, if you did this with C# WPF, you can bind each comboBox in the XAML directly, I am unsure if this can be done in VB.net as I tried to look for the option but did not manage to do so, something you might want to try though.
Some very useful tutorials and guides on Data binding, which you might be interested:
~ denotes recommended reading for your question
MSDN: Connect data to objects
DotNetPerls on DataGridView (note this isn't a combobox, just displaying values)
~ VBNet DataTable Usage from DotNetPerls (this is in relation to 1.)
~ SO Q&A on Binding a comboBox to a datasource
Concepts of Databinding
I have a datagrid that gets an extra column with checkboxes added that is not in its source. I am trying to convert the grid that the user sees to a datatable when a save button is clicked. What I am trying to do is run it through a for loop and check if the rows checkbox is checked and the best solution seems to be converting it to a datatable and checking from there. Most of what I have seen to do the conversion is Dim dt As DataTable = DirectCast(DirectCast(dtgrd, DataGrid).DataSource, DataTable) which wont work for me since the checkbox values that I am checking for are not in the datasource. I am trying to avoid a million postbacks so I am not updating anything when the checkbox changes.
I have a simple VB.NET 2008 app that helps users to edit fields in the database. Simple enough as a first "real" project in .NET, right?
For one table, I am currently using a DataGridView so it can be edited straight up. However, instead of offering the user the entire table, I'd like to group the data by the 'CompanyNumber' column and use a navigator to page through. In other words, I'd like the DataGridView to show me all the lines related to one company, then click the "next" arrow to show the next company, etc.
(I know I could do this with Xceed DataGrid, but I'm using Windows Forms not WPF, and I'd really prefer to do this with "pure" ADO.NET for this project.)
Update 2009-09-28:
So I have created a ComboBox filled from the same BindingSource, and configured its SelectedIndexChanged to change the Filter value on the DataGridView.
But still, filling the ComboBox--which should be easy!--continues to be a problem. I can either:
(a) fill it from the BindingSource, in which case I see multiples of each 'CompanyNumber' and I can't figure out a way to show only distinct values, or
(b) create another TableAdapter in the data source which is just a "Select DISTINCT CompanyNumber..." query, which mostly works, except that that first value of the list changes when I change the selection (e.g. if the ComboBox shows "100, 101, 102, 103" and I pick "102", then the list will show as "102, 101, 102, 103").
Any recommendations?
(Also, bonus if you can suggest how to make the BindingNavigator's arrows page through the 'CompanyNumber' filters instead of the items in the DataGridView... which is what I'd really like to see.)
What you could do is just force the DataGridView to sort CompanyName, this way all rows with the same company name are next to each other and the user can navigate the data grids with the paging that comes with it.
Alternatly, you could follow through with your combobox/DropDownList idea, which would be best. From what I understand when you select an item in the combobox everything in it changes?
Another way is to create two separate buttons, "Previous" "Next", that when clicked, will change the DataGridView's binding source to only show a certain company. You would need to store an array of company names, then store what the current DataGridView's binding source is displaying.
I ended up figuring it out myself, and the solution is clean and simple. Here are the basic steps:
create a DataView off of the table out of the DataSet
use the DataView.ToTable() method to create a new table filtered to only distinct values from the needed column ('CompanyNumber')
create a BindingSource which uses the new DataTable as its DataSource
bind the ComboBox to the new BindingSource
bind the BindingNavigator to the new BindingSource
Because the ComboBox and the BindingNavigator use the same BindingSource, they will update each other with the changes automagically.
Here's the rough code:
Private Sub CoNumsComboxBox_LoadData()
Dim dvCoNums As DataView, dtCoNums As DataTable
dvCoNums = New DataView(Me.ODBCDataSet.Tables("CompanyFundProfile"))
dvCoNums.Sort = "CompanyNumber ASC, FundNumber ASC"
dtCoNums = dvCoNums.ToTable("CompanyFundProfile", True, "CompanyNumber")
CoNums_BindingSource.DataSource = dtCoNums
CoNumsComboBox.DataSource = CoNums_BindingSource
CoNumsComboBox.DisplayMember = "CompanyNumber"
CoNumsComboBox.ValueMember = "CompanyNumber"
'attach handler which changes DataGridView1's filter when this changes
AddHandler ToolStripComboBox1.SelectedIndexChanged, AddressOf CoNumsComboBox_SelectedIndexChanged
CompanyFundProfile_BindingNavigator.BindingSource = CoNums_BindingSource
End Sub