Alright Gents,
Im trying to search a vb.net combo box for an item. The combo box is already bound to dataset. The display member is set to display just a single column of the selected record. I had it set initially so the objects displayed in the combo were a customized class. In this class I specified all the properties I wanted to keep track of and that seemed to work well. However now that I am using the combo box in its bound state it is much more difficult to manipulate the data.
Mission:
To have the user type a number, if the number is contained in the ComboBox, the combo box should then move to that record so that all the other items bound to that control will update as well.
Research:
I have looked into the System.Windows.Forms.BingingManagerBase class and that seems to have the information I need. I just can't figure out the bridge between that and what I'm trying to do. I want to throw something together so I tried to simply do a SQL search against the dataset for the text in the combobox. Unfortunately that requires late binding and my targeted version of the .Net compact framework does not support that.
Here is an example of the late binding I was attempting. (Im working with VB.net 2005, Compact Framework 3.5 I believe:
For i as integer = 0 to combobox.items.count - 1
dim Dsr as Dataset.Row
dim dv as dataview
Dsr = DirectCase(Dv.row, Dataset.Row)
If Dsr(i).DesiredColumn = DesiredRow.Desiredcolumn then
'Do such and such code
End If
Next
I want to be able to search the dataset for a specific record matching a query. After I find that row matching the query I want to be able to move my combo box to the row found in the SQL query. The main problem seems to be that the Combo works in Datarowviews and my datasets are mostly cast to rows pertaining to the DS.
Anyone have some insight on this it would be much appreciated.
Thanks again!
If you know the item that should be set as selected in the combobox you can just set the ComboBox.SelectedItem Property
If you actually do really need to loop through all the items bound to the combobox then once you reach the correct one you can set the ComboBox.SelectedIndex Property.
For i As Integer = 0 To ComboBox.Items.Count - 1
Dim drv As System.Data.DataRowView = Nothing
Dim desiredColumn As String = String.Empty
drv = DirectCast(ComboBox.Items.Item(i), DataRowView)
desiredColumn = Convert.ToString(drv("Tag"))
Debug.WriteLine(desiredColumn)
Next
This seems to find the column value for every record in the combo box allowing me to find the correct index of the text I am searching for. Like I said though, if I could find a way to search through the list of items in the combobox without having to address each one, I would be grateful.
Related
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'm programming in Visual Basic.
I have one form.
Form 1 contains:
nameTextBox
addNameButton
namesListBox
generateButton
week1TextBox
week2TextBox
week3TextBox
week4TextBox
The user needs to go to Form 1 and type a name in the text box, then add the name to the List Box. The user will add 4 names to the List Box. So, the ListBox will contain the names: Adam, Brenda and Carol.
When the generateButton is clicked, the 3 names have to be written to the text boxes in that order. So week1TextBox should contain "Adam", week2TextBox should contain "Brenda", etc... but once the last name (in this case "Carol") is written into the text box, the loop should start over. Ultimately, there may be up to 50 week text boxes (so week50TextBox). So the loop needs to repeat over and over.
As there is a lack of source code in your question, I'm really not sure exactly how the layout should look, I can only offer some advice/suggestions.
I would recommend creating your listbox control, input textbox, and button to add names to the listbox. In addition to these, though, also add a scrollable panel. (Not sure what the exact term for that control is in VB.net; it's been a long time since I've worked with that language.) Because it sounds like there might be a variable number of items on the panel, when the user goes to generate the list of names, I would use the following rough pseudocode:
Dim OutputTexts As New ArrayList ' This is only here if you want to work with these textboxes later
Private Sub CreateOutput() Handles btnGenerate.Click
pOutputPanel.Controls.Clear()
OutputTexts.Clear()
Dim NextX As Integer = 0 ' Pretty much unnecessary value, but included in case you want to mess with this
Dim NextY As Integer = 0
For i As Integer = 0 To Convert.ToInt32(txtWeekCount.Text)
Dim txtName As New TextBox
txtName.Text = lbNameList.Item(i Mod lbNameList.Items.Count)
txtName.Location = new Point(NextX, NextY) ' Play with this as necessary
NextY += 50 ' Play with this as necessary
OutputTexts.Add(txtName)
pOutputPanel.Controls.Add(txtName)
Next
End Sub
Again, this is very much pseudocode, so I would not encourage copying and pasting, but give it a read, make sure you understand all of it, and then try implementing something similar. There might be an easier way to do it, but I have not programmed in VB.NET in probably over 2 years (at least). Nonetheless, the most important thing in here is the following line: lbNameList.Item(i Mod lbNameList.Items.Count). By Mod-ing your indexing variable, you will be accessing items sequentially, and then repeating from the start of the ListBox items collection once i is out of range.
I would also encourage you to dynamically generate your TextBox controls as needed rather than manually adding in 50 or more TextBox controls.
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 listbox with multiple selection activated and i am trying to read the different selected values
I have tried many snippets, here are the latest two :
For i = 0 To ListBox1.SelectedIndices.Count
MsgBox(ListBox1.Items((ListBox1.SelectedIndices(i))).value)
Next
For i = 0 To ListBox1.SelectedItems.Count
MsgBox(ListBox1.SelectedItems(i).value)
Next
For some reason with any approach i choose i can't read any item's value
My listbox is data bound, so i found out on a forum that making it public might fix the issue but it did not
I am hesitating as even Intellisense doesn't show much info, all i get is :
Equals
GetHashCode
GeType
ReferenceEquals
ToString
Any ideas where i went wrong?
Thanks in advance
Edit:
I'm not a big fan of using the Data GUI tools in VB. That said, I think what you are looking for is this:
For Each dvRow As DataRowView In Me.Listbox1.SelectedItems
MessageBox.Show(dvRow("Id").ToString)
Next
If you were interested in the Last Name field, change "Id" to "Last Name".
Also, I used MessageBox.Show instead of MsgBox. MsgBox is a leftover from VB6.
When you use a databound ListBox, the items aren't ListBoxItem objects (which you would expect to have Text and Value properties). Rather they are the type from the data source. The Items collection (and its variations, such as SelectedItems) is defined as a collection of objects, and the runtime type is obtained from the data source. Have you tried something like this?
For i = 0 To ListBox1.SelectedItems.Count
MsgBox(ListBox1.SelectedItems(i).ToString())
Next
In the comments, you indicated that the data source is a DB object containing String objects. If you have a collection of classes, such as Person, you can get it this way:
For i = 0 To ListBox1.SelectedItems.Count
MsgBox(DirectCast(ListBox1.SelectedItems(i), Person).FirstName)
Next
You should also get the same results with a For Each, as long as the selected items collection isn't changed while you are looping.
For Each p As Person in ListBox1.SelectedItems
MsgBox(p.FirstName)
Next
NOTE: This is untested code, as I'm not in front of Visual Studio at the moment.
EDIT: I see from the screenshot that the Value Member is set to a property named Id. If that is a uniqueidentifier column from the database, then the runtime type in the ListBox should be Guid.
Code in Form onLoad:
country_combo.RowSourceType = "Value List"
Code in a reset function:
Dim lListIndex As Long
With Me.country_combo
For lListIndex = .ListCount - 1 To 0 Step -1
.RemoveItem (lListIndex)
Next lListIndex<br/>
End With
Code to populate country combo:
*For n = 1 To numCountries*
*countryCombo.AddItem (countryRS.Fields("countryName"))*
*countryRS.MoveNext*
*Next n*
I'm having a problem that occurs AFTER the code to populate the country combobox runs. The values are there as I can run Debug.Print(countryCombo.Value) and it prints out the name of the selected country, but I can't see the values in the combobox at all. They're invisible, and as far as I know there is no visiblity property for specific items, unless I'm completely mistaken.
comboBoxError.png http://img110.imageshack.us/my.php?image=comboboxerror.png
I think you should probably use Access's GUI tools to do what you're looking for. In design mode, click on the field you are trying to populate, then click the "lookup" tab. You can then specify a table to populate the field with and your forms should automaticly update as well.
I've also seen what you describe here - as far as I can tell, it's a bug within Access (I was using 2007) that only occurs when you programatically mess with the contents of a combo box. It does not happen every time. The issue corrects itself if you highlight the text that is in the combo box.
I am experiencing a similar issue with Access 2003. Based on the selection of one combo box, the row source of a listbox is set to an SQL string Basically a SELECT DISTINCT [MyField_Selected] FROM MyTable. For some fields the values are visible in the list box and others it is not. The values are there however as I can access them via code. To make it more interesting it works fine in Access 2007.
Just found the resolution on another forum. Check the format property of the field(s) in question on the table. In my case, when Access 2007 created the table, it put an # format in there. I removed that and all works great!