Develop Reference

How can I make a ComboBox auto post back in WinForms application?

I have a Windows Forms application for employees and when I select the employee name
from a ComboBox, textboxes should be filled with the data of the selected employee. I remember something like the auto postback property but I can't find it in Visual Studio.
Thanks in advance.

If you're using WinForms, there's no such thing as AutoPostBack, that is for ASP.NET. In your case use the SelectedIndexChanged-event. In this event you can get the selected item and based on this item, get the corresponding data of the employee and fill the textboxes.
More info:
MSDN: ComboBox.SelectedIndexChanged Event
Pseudo-code:
private void YourComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
string item = (string)YourComboBox.SelectedItem;
//Fetch data (dummy method)
Employee emp = GetDataByName(item);
//Write to TextBox
SomeTextBox.Text = emp.Function;
}

Winforms provides the following events:
SelectedIndexChanged Occurs when the SelectedIndex property has
changed. SelectedValueChanged Occurs when the SelectedValue
property changes.
You can read more about them here: MSDN Combobox.

You should use the SelectedIndexChanged event of the Combobox. Normally you'll get it when you double click to the ComboBox on your form.
In order to store a text with a value (suppose ID) and add it to the Combobox, follow this answer:
https://stackoverflow.com/a/11745699/870865
For an Example:
// On load event, add the items to the ComboBox following the above link I have posted...
private void cmbEmployees_SelectedIndexChanged(object sender, EventArgs e)
{
int EmployeeID = ((KeyValuePair<string, string>)cmbEmployees.SelectedItem).Value;
var Employee = SomeClass.getEmployeeByID(EmployeeID); // Write a class or a method to get Employee as an object...
txtName.Text = Employee.Name;
txtEmail.Text = Empolyee.Email;
}
Hope this gives you an idea!

get the clicked item from a IsItemClickEnabled ListView in C# and WinRT

how can I get the clicket elevent from a ListView which has the IsItemClickEnabled enabled?
I know how to get the selected Item/Index but not the clicked item.
ItemClick is working but I can not say s.th. like:
Object selection = listView1.SelectedItem;
EDIT:
I have a ListView and I need to catch the clicked item from this list in the following method:
private void listView1_ItemClick(object sender, ItemClickEventArgs e)
{
...
}

I may be missing something, but doesn't the following work for you?
private void lv_ItemClick_1(object sender, ItemClickEventArgs e)
{
var item = e.ClickedItem as String;
}
Here I assume the items in the list are simple strings, but in general they'll be whatever type you are using in the collection you've bound to the ItemsSource property of the ListView.

I guess you can also try the SelectionChanged event, and get the clicked item as e.AddedItems or MyListView.SelectedItem or MyListView.SelectedItems.

Can't get value from ComboBox control

I try to use combobox in winforms project.
Here is my code:
private void ShowContoursForm_Load(object sender, EventArgs e)
{
cbxSelectShape.DisplayMember = dataSetObject.ObjectShapes.ShapeNameColumn.ColumnName;
cbxSelectShape.ValueMember = dataSetObject.ObjectShapes.ShapeIDColumn.ColumnName;
cbxSelectShape.DataSource = dataSetObject.ObjectShapes;
}
private void cbxSelectShape_SelectedValueChanged(object sender, EventArgs e)
{
var id= (int)cbxSelectShape.SelectValue;
}
When I choose item from ComboBox SelectedValueChanged is fired,and id variable gets null.
I need to get value of selected item but I always get null in id variable.
Any idea why do I get wrong result and how to fix this code?

You can get the index of ComboBox this way:
private void cbxSelectShape_SelectedValueChanged(object sender, EventArgs e)
{
var id= ((ComboBox)sender).SelectedIndex;
}

You should use SelectedValue property of combobox to get value, associated with ValueMember (ShapeID in your case):
var id = ((ComboBox)sender).SelectedValue;
SelectedIndex returns index of item selected in combobox. Also if this handler used for one combobox, you don't need to cast sender - simply use your combobox variable:
var id = cbxSelectShape.SelectedValue;

ComboBox text change failure

I am calling the following on ToolStripMenu item click :
protected void windowNewMenu_Click(object sender, EventArgs e)
{
if (_selectedThings.Contains(((ToolStripMenuItem)sender).Tag))
{
selectedItemsPropertyGrid.SelectedObject = ((ToolStripMenuItem)sender).Tag;
selectedItemsComboBox.SelectedText = (((ToolStripMenuItem)sender).Tag.GetType()).ToString();
}
}
However the second line that is supposed to change does not seem to produce any visible changes to the ComboBox. Any Suggestions?

SelectedText is for highlighting a portion of the text, not selecting an item in the list. For that, you need SelectedItem.
Or you can just use:
selectedItemsComboBox.Text = ...

DataGridViewCombBoxColumn cell value and different dropdown list

I've a very trivial requirement which makes me go nuts. I've a DataGridView in windows forms application. This contains one databound ComboBox Column. I'm using DisplayMember and ValueMember properties of that combobox.
Now my requirement is ComboBox should show the list of DisplayMembers in drop down list but when user selects one item from it, I should display the part of that DisplayMember in the combobox cell visible to the user. For example.
My display member list looks as below:
"Cust1 - Customer 1"
"Cust2 - Customer 2"
"Cust3 - Customer 3"
and when user selects any one of them from the above list (Say user selected 'Cust2 - Customer 2') then I need to display the value in the combobox column cell as only "Cust2" instead of complete DisplayMember text.
This DisplayMember list is a combination of two fields from the datasource bound to it i.e. First part points to CustomerCode field and second part points Customer name. I need to display only CustomerCode in the ComboBox cell after user selects one item from the drop down list.
How can I do this? Or should I come up with my own control which will have a different AutoCompleteCustomSource and display member value. Even I'm confused with that approach too.
Update: As no one has come up with any solution to my problem. Now I'm starting a bounty for that, also if anyone can suggest me other way to implement the same functionality, it would be great.
I've even tried to come up with my own control and tried to work on simple combobox to display a different value than the selected dropdown list, even that didn't work. Is there any other way to implement this? Any tips and tricks are greatly appreciable.
#Anurag: Here is the code which I've used.
Created a datagridview in the design mode. Created one column of type 'DataGridViewComboBoxColumn' that and named it as CustomerColumn.
In the designer file it looks like below:
private System.Windows.Forms.DataGridViewComboBoxColumn CustomerColumn;
This is the entity class which I've used for datasource
public class Customer
{
public int Id { get; set; }
public string CustCode { get; set; }
public string CustName { get; set; }
public string NameWithCode { get; set; }// CustCode - CustName format
}
In the form load event I'm doing the following:
CustomerColumn.DataSource = GetCustomers();
CustomerColumn.DisplayMember = "NameWithCode";
CustomerColumn.ValueMember = "Id";

I'm answering my own question because I've implemented my own solution to this by using custom control.
This custom control is created by keeping a textbox above combo box in such a way that only drop down button of combobox is visible.
Now I've created a custom column in datagridview deriving the DataGridViewEditingControl from my usercontrol.
I've added a property in Usercontrol which will take drop down list source from the control which is hosting datagridview.
Now in the EditingControlShowing event I'm setting this property as below
private void dataGridView2_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
if(dataGridView2.CurrentCell.ColumnIndex.Equals(0) && e.Control is UserControl1)
{
var uscontrol = e.Control as UserControl1;
uscontrol.DropDownListSource = source;
}
}
This drop down list source is used in the usercontrol to set the autocompletesource to the textbox and datasource to the combobox as below:
Whenever I set the DropDownDataSource I'm firing an event in the usercontrol which will do the following. This is to ensure that every time EditingControlShowing event occurs for this column in DataGridView, this source is updated for textbox and combobox in usercontrol.
private void DropDownSourceChanged(object sender, EventArgs eventArgs)
{
textBox1.AutoCompleteCustomSource = DropDownListSource;
textBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;
comboBox1.DataSource = DropDownListSource;
}
Now whenever user starts typing in the textbox autocomplete source will display dropdown list with 'NameWithCode' values and if user selects one of them then I'll set it to the Text propery overidden in my usercontrol which will be used for the cell value in the DataGridView. Now based on the Textbox text (which is NameWithCode) I can get the code part and set it to the text property.
If user uses combobox dropdown button to select the item then I'll get the combobox selected text and set it in the Textbox which is ultimately used by the cell for getting value.
This way I could achieve the solution I want.
#Homam, solution also works but when I change the ComboBox's DropDownStyle to allow the user to type the value in the combobox it behaves weirdly and not getting up to the mark solution for my requirement. Hence I used this solution.

I know that this is not perfect solution, but I looked for a better one and I didn't find, so I went to a workaround
I did the following:
when the user open the ComboBox, I change the DisplayMember to "NameWithCode"
when the user close it, I return it to "CustCode"
You can Access to the ComboBox control by DataGridView.EditingControlShowing event for the DataGridView.
The code:
private void dataGridView1_EditingControlShowing(object sender,
DataGridViewEditingControlShowingEventArgs e)
{
var comboBox = e.Control as ComboBox;
comboBox.DropDown += (s1, e1) => comboBox.DisplayMember = "NameWithCode";
comboBox.DropDownClosed += (s2, e2) =>
{
// save the last selected item to return it after
// reassign the Display Member
var selectedItem = comboBox.SelectedItem;
comboBox.DisplayMember = "CustCode";
comboBox.SelectedItem = selectedItem;
};
}
Note: You have to start the DisplayMember with "CustCode"
Good luck!

Each time at the offensive of event dataGridView1_EditingControlShowing there is addition of new handlers for events comboBox.DropDown and comboBox.DropDownClosed. It results in the increase of number of these handlers and their repeated calls. This code decides this problem.
private void dataGridView1_EditingControlShowing(object sender,
DataGridViewEditingControlShowingEventArgs e)
{
var comboBox = e.Control as ComboBox;
comboBox.DropDown += comboBox_DropDown;
comboBox.DropDownClosed += comboBox_DropDownClosed;
}
private void comboBox_DropDown(object sender, System.EventArgs e)
{
var comboBox = sender as ComboBox;
if(comboBox != null)
{
comboBox.DropDown -= comboBox_DropDown;
comboBox.DisplayMember = "NameWithCode";
}
}
private void comboBox_DropDownClosed(object sender, System.EventArgs e)
{
var comboBox = sender as ComboBox;
if(comboBox != null)
{
comboBox.DropDownClosed -= comboBox_DropDownClosed;
var selectedItem = comboBox.SelectedItem;
comboBox.DisplayMember = "CustCode";
comboBox.SelectedItem = selectedItem;
}
}