Adding An Empty Row To A Databound Listbox Using Linq2SQL And Winforms?
Sep 28, 2011
what is the most robust method for adding a empty row (to select "nothing") to a ListBox?
Dim List = Enumerable.Repeat(New TABLE With {.Text = "", .ID = -1}, 1).AsQueryable().Union(From t In mainctx.TABLEs)
ddlMangelKategorie.DisplayMember = "Text"
ddlMangelKategorie.ValueMember = "ID"
ddlMangelKategorie.DataSource = List.ToList
But this has some drawbacks:wordy must explicit write the Type (TABLE in this case), so i cant wrap this in a function have not found an solution, which works with anonymous types I.e. if I add a From t In mainctx.TABLEs Select Text=col1, id=col2 to the query, this method does not work anymore.
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Sep 29, 2010
I want to manually add two items as "Active" and "Inactive" in a ListBox. When the user selects "Active", I want to get the value "A" and when "Inactive" is selected, I want to get "I". How do I do this in VB.NET.
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Oct 18, 2010
How to avoid getting empty fields in a databound combo box?
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Oct 30, 2009
I have a UserControl, with a TextBox and a databound property - Value.Value can be any object such as a Color, Array, Font etc.Any time the text changes, the property Value is changed as long as it is valid.Looking at the msdn article: How to: Apply the PropertyNameChanged Pattern , it says I should use the PropertyNameChanged Event patternfrom the control side.Now, If I have DataSourceUpdateMode = OnValidate, then I don't even need to apply this pattern. If, say. my Value property is bound to a colour field in a business object, then after I type red, in the textbox and tab to another field, then any other fields on the form, that bind to the same colour field, are updated immediately.
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Apr 13, 2009
The problem I have is that many times, the dataset that this control is bound to is empty. Therefore, the user continuously gets an error saying that one or more fields is missing. When I debug the code, I can see the code in the class loop through all of the radio button controls on the form. Since none of them match the field from the database, the code throws the error. I assume the code expects a match.
Should I modify the class to handle the case when there is a DBNull value? If so, what would be the best method? Or should I approach this situation in a completely different manner?
Public Class myGroupBox
Inherits GroupBox
Private _myTag As String
[Code]....
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Mar 2, 2012
I've pretty much just started in playing with Visual Basic Studio 2010 and have been using this site for lots of answers so thought I'd join up and harass more directlyI've been trying to move items between two lists, one is databound to a bindingsource, the other isn't. I found out that you can't really move items from databound lists, but you can remove from the datasource instead. This works fine until I want to move the item back - it fills a blank line with seemingly no data.
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Apr 27, 2010
I've inherited a form that has a DataGridView that is bound to a dataadapter and it is connected to a binding source. Within the DataGridView is a combo box that is bound to its own bindingsource which basically just calls a stored proc to bring back the possible values for the dropdown combo control
With a blank new row and sometimes even with an existing row, this value for the combo box can be NULL which is a legitimate value for it if no value selected. Problem is everything is so tightly bound if the user mistakinly clicks the dropdown then a value is populated and there's no way to get back to NULL
I've tried to catch the mousecelldown event and others to try to catch this before a value is selected but the Cancel=True doesn't work - I can catch the event but don't know how to return the cell to unclicked or reset it to NULL or pre selected value if NULL I know how to at a new row with the datatable and then set the combo datasource to it and I have my null blank value but with a tightly bound control how do I add this row?
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Mar 13, 2011
I have a Listbox which is to display a list of product names which it reads from a database table, bound using the inbuild datasource/databinding stuff..however when the product names are updated/more are added in the table etc no change is reflected in the Listbox! only the initial names from when it was first bound appear, how to fix this?
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Jun 21, 2012
I am just adding validation into a new winform. I am using the validating and validated events, in conjunction with an error provider control.No problem with first validation (ie. if user enters more than 12 characters). Error is set in validating event, and error stays until user enters 12 or less characters. Validated event is then entered and error is reset to empty string.
However, there is a problem with the 2nd validation on same text box. The code checks for zero length in text box.. and sets error with provider. Watching in the debugger, this code is indeed invoked, and error is set ok. Then something weird happens, the validated event is (unexpectedly) fired, and the code there promptly resets the error. Why is the validated event fired when there is already an error set ? This seems like a .NET bug. Can anyone suggest another way of doing this, or say what I am doing wrong ?
[Code]...
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Jun 21, 2012
HStrange Issue Validating Empty Text Box in Winforms
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Dec 4, 2011
I'm making an WPF-application that has a databound ListView. When loading the application, the width of the ListViewColumns will auto-resize, but when adding or changing an item it doesn't auto-resize. I've tried refreshing the listview, setting the width of the column to auto, -1 or -2 in both xaml and VB-code and I've tries changing the itemssource to nothing before refilling it with items.
This is the xaml code:
<ListView x:Name="lsvPersons" Margin="5,5,5,35" ItemsSource="{Binding Persons}">
<ListView.View><GridView>
<GridViewColumn DisplayMemberBinding="{Binding Name}" Header="Name"/>
<GridViewColumn DisplayMemberBinding="{Binding Gender}" Header="Gender"/>
<GridViewColumn DisplayMemberBinding="{Binding Age}" Header="Age"/>
[Code] .....
After pressing the button, a window will open to add a person. After the window is closed, the item is added to the listview with following code, which refreshes the items in the listview:
lsvPersons.ItemsSource = Person.getPersons()
So, what do I need to do to auto-resize the columns of the listview when an item is added or edited?
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Mar 17, 2011
I have a question regarding Databound listbox (Item selection)I have not used the listbox much so I am very uncurrent in it's use:What I am wanting to to is connect to a database, select from the database (lastname) then display the list of names in the listbox, also have a datagrid on the same form, so that when I click on a name on the listbox the datagrid moves to that same record.
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Feb 7, 2010
I am having trouble adding a row to a databound datagridview on a parent form from a child form. I have two forms, one contains a datagridview that is bound to a table using 'datagridviewbindingsource' and contains an 'add' button. The second contains a checked listbox that is populated correctly and has a "Cancel" and an 'OK' button - when i check several items in the child form, i would like to hit okay and update the bindingsource of the datagridview on the first form with the checked items.
Code:
in form1 when btnAdd is clicked
dim f2 as new form2
'call it as a dialog to check for the cancel button
f2.ShowDialog()
[Code] .....
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Mar 22, 2012
It appears that I cannot assign the selectedindex for a databound listbox if it has no parent, but I can do so if I have populated the list "manually" from the same datatable. In my code example, the "if" line toggles between loading a list via data binding and loading a list "manually" (both use the same data table). In each case I attempt to set the selected index afterwards. With manual loading, the selected index is set; with data binding, an error is thrown (which can be avoided by assigning the listbox a parent, but the "manual" equivalent doesn't need this). Is this a bug?
[Code]...
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Jun 12, 2011
As the title says I have a form with many databound textboxes. some of these boxes have data in them and some are empty. I need to add them altogether, so far all of the conversion methods I have tried err out when they run into an empty string, except Val, but then Val won't handle the string with a $ in it. I've tried decimal.parse which handles the $ but not the empty string. So I seem to be in circle that I can't get out of.
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Jan 3, 2011
I need to give the user an ability to add rows. i can't figure out what control to use to accomplish this. for example
first row with empty text boxes is always visible:
[first name] [last name] [middle name]
add more button
[code]......
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Jan 9, 2012
Check this:Can I add ListViewGroup in WPF? Or a equivalent to that?
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Jan 6, 2012
This works:
DataGridView.Rows.Add("Bla Bla Bla", value1, value2)
But if I do:
Dim newrow As New DataGridViewRow
newrow.SetValues("Bla Bla Bla", value1, value2)
If Not value1.Equals(value2) Then
[Code]....
the entire row is empty.
Why is the row full of empty cells?
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Feb 15, 2012
In WinForms, is there a way to add an item to the popup menu when you click on the icon in the forms control bar? Apps I can think off that use this is Chrome, and Command Prompt.
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Oct 19, 2010
I have a calculator like program which has a function to export a string ('StringBuild') to notepad .The process start OK but it has a funny problem. When I run Process.Start it also keept running a sub that I had linked to one of the calculator buttons.I played around with the code but now it runs a hyperlink that I have on the calculator. I even tried adding an empty, hidden, button as the last item on the tabindex to see if that would work but it hasn't.
Process.Start("Notepad.exe")
SendKeys.Send(StringBuild.ToString)
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Jan 27, 2012
I am using visual studio 2010, service-based database. I created a simple table and created an edit form for that table. But when I save a row and then clear the text of a textbox (which holds a decimal value), it simply does not let me tab off the text box or save it. I put a ErrorProvider to see whats going on. It says "Input string was not in correct format". But I allowed this column to be null in my table. So how do I fix this error. And by the way, it does not happen for all text boxes.
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Jan 14, 2009
I was wondering how to check if a list box is not empty I have inserted my code I want t check if there if text in the listbox and if there is no text do some thing. I have put the line of code i am having trouble with in red
result = MsgBox("Are you sure you wish to make the required number of lockers", MsgBoxStyle.YesNo, "Confirm Order")
If (result = MsgBoxResult.Yes) Then
CheckLevels()
If lstOrder.NoItems = True Then
[Code]...
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Jun 26, 2006
Adding an item to the System Menu in WinForms
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May 30, 2011
I was just wondering if there was a possible way to add a custom button into the title bar using VB.NET. I've seen many such questions on Stack Overflow but failed to get a sure-shot and a working answer.
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Oct 21, 2009
I have a WinForms application that I need to dynamically add controls to at runtime. I searched for this and I was initially led to the TableLayoutPanel (TLP).
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Jun 9, 2012
I need to know if there is a way to remove any items from a listbox if they contain no text. Like if there are three items(Blah, ,Blah) listed in the listbox like so (remove the middle line that is empty so the listbox now contains two items(Blah, Blah) listed like so Or if there is a way to do this to a textbox that would work too. I'm working in VB 2010
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May 24, 2011
I was wondering if it is possible to add a button to the title bar in vb.net - I found a way to do this in one or the other but is it possible to do it on both?Here is the code that works if Aero is disabled (imports System.RunTime.InteropServices):
[Code]...
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Mar 17, 2011
how do i draw image in listbox_DrawItem event by the left side
Dim targetsize As New Size(16, 16)
Dim img As Image = Nothing
img = My.Resources._error
[Code]....
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Dec 23, 2009
How to get the handle of a ListBox control in VB.NET 2005?
I am using
Dim i_Handle As ListBox
i_Handle = ListBox1.Handle
But this is not working
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Dec 15, 2011
I've got a Program and a text file, this text file gets load into the list box but that's not the problem. The problem is that when I make the text file it makes a open line and this line gets loaded into the list box and I don't want empty items.
So here's code that I use to make text file
Public MySettingfile As String = My.Application.Info.DirectoryPath & "Process History.MemFreo" Dim myCoolWriter As New IO.StreamWriter(MySettingfile, True, System.Text.Encoding.Default)
myCoolWriter.WriteLine()
myCoolWriter.Close()
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