Develop Reference

Error on Combo box as User Control element

I'm creating a user control with a Combo box, Text box and a Button. When I place this User Control in a form following error occurred. "Cannot bind to the new value member. Parameter name: newDisplayMember" I searched the SO and couldn't find any satisfying answer (May be I'm wrong). This is the code snippet to load data to combo:
// binding data source.
_bsFieldList.DataSource = _dtFieldList;// _dtFieldList is a DataTable
// Assigning binding source as the data source of the combo box.
cboFields.DataSource = _bsFieldList;
cboFields.DisplayMember = "FieldCaptn";
cboFields.ValueMember = "FieldType";
What Am I doing wrong?
I found that using public properties for DisplayMember and ValueMember solved this issue. But in my case this is not possible.
EDIT:
These are the columns of _dtFieldList

Combobox newly selected item event not functioning correctly C#

I have a combobox which is populated by a binding source. I'm trying to get my program to do the following, when the selection is changed it carries out the following command:
dataSetInstance.tbl2.Clear();
oleDbDataAdapter1.SelectCommand.Parameters[0].Value = label2.Text;
oleDbDataAdapter1.Fill(dataSetInstance.tbl2);
As a button the above piece of code works and I get the results I'm after, but using the comboBox1_SelectionChangeCommitted method with the same code it seems I have to select the item in the combo box twice to gain the same results as the code I've used above in a button click.
Many thanks,

Instead of SelectionChangeCommited, try using SelectedIndexChnaged.
Have a look at this sample on MSDN:
ComboBox.SelectedIndexChanged Event

C# Datagridview: get selected item in combobox columns

I'm working on a GUI that allows the user to manipulate xml files. I display the xml file in a datagridview organized neatly by columns through xml elements. I allow the user to add columns as an extention on my project. The column gets added to the dataset table, then updated to the datagridveiew that I use to display the xml file in. I've included the ability for the user to add a combobox column to select choices instead of entering them in constantly like.. true or false. However, that is where the problem lies. Saving a normal column was easy. The combobox column is being a pain.
I have a "save combobox column" to have it updated to the xml and a "save" button to save in a destination of the user's choice.
I've done some research and it seems like the combobox class has such a feature to gain access to the selecteditem in the combobox put in by the user.
Where we have:
ComboBox box = new ComboBox();
box.SelectedItem;
I tried applying this to the combobox column class but it does not have such a function. Thus, I cannot figure out how to directly obtain the value of the user's selected item. I tried experimenting with comboboxcell's as well, but that didn't lead me anywhere either. Both those classes I played around with do not have a... "selected item" function and even google does not have a solution for me. =( I've also tried using the cell.value, but it is "null" for some reason. Even when the user selects an item in the box, it doesn't get saved into the cell's value.
TLDR:
My question in short is, how, if possible, do you gain access to the comboboxcolumn cell's selected item? Additionally, how would you then ensure that the item value is saved in the cell?
Thanks in advance. I'm using .NET 3.5 SP1, through Visual Studio 2008 C#.
Sincerely,
tf.rz

The Control in a DataGridView is not a ComboBox, it is a DataGridViewComboBox and has different properties and methods. From MSDN
Unlike the ComboBox control, the DataGridViewComboBoxCell does not have SelectedIndex and SelectedValue properties. Instead, selecting a value from a drop-down list sets the cell Value property.
However, you mentioned that the Cell.Value is null for you. Well there may be another step you are missing according to the following article (How to: Access Objects in a Windows Forms DataGridViewComboBoxCell Drop-Down List).
You must set the DataGridViewComboBoxColumn.ValueMember or DataGridViewComboBoxCell.ValueMember property to the name of a property on your business object. When the user makes a selection, the indicated property of the business object sets the cell Value property.

If we have bound a datagridcomboboxcell with a different DisplayMember and ValueMember, like so:
dgcombocell.DisplayMember = "Name";
dgcombocell.ValueMember = "Id";
dgcombocell.DataSource = dataset1.Tables[0];
Then for getting SelectedText, and SelectedValue, we can write this code:
string SelectedText = Convert.ToString((DataGridView1.Rows[0].Cells["dgcombocell"] as DataGridViewComboBoxCell).FormattedValue.ToString());
int SelectedVal = Convert.ToInt32(DataGridView1.Rows[0].Cells["dgcombocell"].Value);
I hope it solves your problem.

Use this to get or set selected value:
object selectedValue = currentRow.Cells["comboboxColumnName"].Value
Don't forget to set DisplayMember and ValueMember for your DataGridViewComboBoxColumn

This is how it is done
DataGridViewComboBoxCell comboCell = (DataGridViewComboBoxCell)dgv.Rows[0].Cells[1];
MessageBox.Show(""+comboCell.Items.IndexOf(comboCell.Value));

A .Net combox is actually a composite control made up of a textbox and a dropdownlist. Use box.Text to get the currently displayed information.
EDIT: The row or the cell should have a .FindControl() method. You'll need to do something like:
Combobox box = (Combobox)(row.FindControl("[combobox ID]"));
string val = box.Text;
Basically, you're finding the control within its container (row or cell), then casting the control found as a combobox, then accessing its .Text property.

I use this:
private int GetDataGridViewComboBoxCellSelectedIndex(DataGridViewCell d)
{
return ((DataGridViewComboBoxCell)d).Items.IndexOf(d.Value);
}

How do I set a ComboBox default *not in the drop down* when a list item begins with the same text as a drop down item?

Using C#, say you have a ComboBox that has a DropDownStyle set to DropDown (there are items in the drop down but the user can manually enter a value as well). How do you set a default value for the ComboBox that is not in the list of values in the drop down, but begins with text from a possible selection? Normally setting ComboBox.Text works fine, but if there is an item in the drop down that begins with the text you want as the default, it automatically selects the first item in the list that starts with the text. For example:
Values in the drop down:
c:\program files\
c:\windows\
d:\media\
Default Value Assignment
myComboBox.Text = "C:\";
Result
Initial value of ComboBox when the form opens is "c:\program files\".
So what am I doing wrong? How do I correctly set a default value of an item not in the drop down list that begins with a possible selection?

Does the following code work?
myCombo.SelectedIndex = myCombo.FindString(#"c:\");
Note: I haven't tried it. Looked up for properties/methods that could help using reflector.

I couldn't repro the behavior you are describing. Adding the three values via the Items collection and then setting the initial value to "c:\" (you omitted an # in your code sample, by the way) worked fine. My guess is that something else in your code is setting the value of the combo box after you set it.

I was able to get this to work with having the items in the ComboBox be ComboBoxItems (I dont see why this wouldn't work with other types). Set the ComboBox.Text like you are and make sure SelectedIndex = -1 and also you need IsEditable = True.

How to retrieve a changed value of databound textbox within datagrid

ASP.NET 1.1 - I have a DataGrid on an ASPX page that is databound and displays a value within a textbox. The user is able to change this value, then click on a button where the code behind basically iterates through each DataGridItem in the grid, does a FindControl for the ID of the textbox then assigns the .Text value to a variable which is then used to update the database. The DataGrid is rebound with the new values.
The issue I'm having is that when assigning the .Text value to the variable, the value being retrieved is the original databound value and not the newly entered user value. Any ideas as to what may be causing this behaviour?
Code sample:
foreach(DataGridItem dgi in exGrid.Items)
{
TextBox Text1 = (TextBox)dgi.FindControl("TextID");
string exValue = Text1.Text; //This is retrieving the original bound value not the newly entered value
// do stuff with the new value
}

So the code sample is from your button click event?
Are you sure you are not rebinding your datasource on postback?

When are you attempting to retrieve the value from the TextBox? i.e. when is the code sample you provided being executed?
If you aren't already, you'll want to set up a handler method for the ItemCommand event of the DataGrid. You should be looking for the new TextBox value within that method. You should also make sure your DataGrid is not being re-databound on postback.
I would also highly recommend reading through Scott Mitchell's excellent article series on using the DataGrid control and all of it's functions:
https://web.archive.org/web/20210608183626/https://aspnet.4guysfromrolla.com/articles/040502-1.aspx