How to show text in combobox when no item selected

Question

C   amp   Net 2 0 question  WinForms   I have set of items in ComboBox and non of them selected  I would like to show a string on combo  Please select item  in that situation    Current implementation is just added empty item with such text on index 0 and remove it when user select one of following items  Unfortunately empty item is shown in dropdown list as well  How to avoid this situation or in other way - is there any way to show custom text on ComboBox when no item is selected   Answers below work when ComboBoxStyle is set to DropDown  ComboBox is editable   Is there possibility to do this when ComboBoxStyle is set to DropDownList

User · Answer

I used a quick work around so I could keep the DropDownList style.

class DummyComboBoxItem
{
    public string DisplayName
    {
        get
        {
            return "Make a selection ...";
        }
    }
}
public partial class mainForm : Form
{
    private DummyComboBoxItem placeholder = new DummyComboBoxItem();
    public mainForm()
    {
        InitializeComponent();

        myComboBox.DisplayMember = "DisplayName";            
        myComboBox.Items.Add(placeholder);
        foreach(object o in Objects)
        {
            myComboBox.Items.Add(o);
        }
        myComboBox.SelectedItem = placeholder;
    }

    private void myComboBox_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (myComboBox.SelectedItem == null) return;
        if (myComboBox.SelectedItem == placeholder) return;            
        /*
            do your stuff
        */
        myComboBox.Items.Add(placeholder);
        myComboBox.SelectedItem = placeholder;
    }

    private void myComboBox_DropDown(object sender, EventArgs e)
    {
        myComboBox.Items.Remove(placeholder);
    }

    private void myComboBox_Leave(object sender, EventArgs e)
    {
        //this covers user aborting the selection (by clicking away or choosing the system null drop down option)
        //The control may not immedietly change, but if the user clicks anywhere else it will reset
        if(myComboBox.SelectedItem != placeholder)
        {
            if(!myComboBox.Items.Contains(placeholder)) myComboBox.Items.Add(placeholder);
            myComboBox.SelectedItem = placeholder;
        }            
    }       
}

If you use databinding you'll have to create a dummy version of the type you're bound to - just make sure you remove it before any persistence logic.

User · Answer

Here s how I do it   It might not be the best method  and offers least control  however  it s simple and quick and I thought it might be a good idea to share it so that more options are available for others    lt ComboBox SelectedIndex  0  gt       lt ComboBoxItem Visibility  Collapsed  gt Please select one    lt  ComboBoxItem gt       lt ComboBoxItem gt 1 lt  ComboBoxItem gt       lt ComboBoxItem gt 2 lt  ComboBoxItem gt       lt ComboBoxItem gt 3 lt  ComboBoxItem gt       lt ComboBoxItem gt 4 lt  ComboBoxItem gt   lt  ComboBox gt    The idea behind this is that the initial selection is index 0  which is collapsed  so it s not available under selection for the user once they select something else   The downside is that you have to remember that if you re checking for a selected index  remember that index 0 means there was no selection made

User · Answer

I can t see any native  NET way to do it but if you want to get your hands dirty with the underlying Win32 controls     You should be able to send it the CB GETCOMBOBOXINFO message with a COMBOBOXINFO structure which will contain the internal edit control s handle  You can then send the edit control the EM SETCUEBANNER message with a pointer to the string   Note that this requires at least XP and visual styles to be enabled

User · Answer

Credit must be given to IronRazerz in a response to TextBox watermark  CueBanner  which goes away when user types in single line TextBox  not for RichTextBox    You will need to declare the following in your class   private const int CB SETCUEBANNER   0x1703    System Runtime InteropServices DllImport  user32 dll   CharSet   System Runtime InteropServices CharSet Auto   private static extern int SendMessage IntPtr hWnd  int msg  int wParam   System Runtime InteropServices MarshalAs System Runtime InteropServices UnmanagedType LPWStr  string lParam     Then you can use it with something like   SendMessage this comboBox1 Handle  CB SETCUEBANNER  0   Please select an item         This is assuming the Combo Box s DropDownStyle is set to DropDownList  as is the original poster s question   This should result in something like the following

User · Answer

One line after form InitializeComponent     cbo MyDropBox Text    Select a server        You only need it once right  All you need to do if a pick is mandatory is check if the box index    -1  Could anyone elaborate why the other answers jump through hoops to get this going    The only thing I m missing here is having just this initial text grayed out  If you really want that just use a label in front and turn it off once the index is changed

User · Answer

Why not do it XAML    lt ComboBox x Name  myComboBoxMenu  PlaceholderText  Hello   gt

User · Answer

Here you can find solution created by pavlo ua  If you have  Net   2 0 and  If you have  Net    2 0  search for pavlo ua answer   Cheers  jbk  edit  So to have clear answer not just link  You can set Text of combobox when its style is set as DropDown  and it is editable   When you have  Net version  lt  3 0 there is no IsReadonly property so we need to use win api to set textbox of combobox as readonly   private bool m readOnly   false  private const int EM SETREADONLY   0x00CF   internal delegate bool EnumChildWindowsCallBack  IntPtr hwnd  IntPtr lParam      DllImport  user32 dll   CharSet   CharSet Auto   internal static extern IntPtr SendMessage IntPtr hWnd  int msg  IntPtr wParam  IntPtr lParam      DllImport   user32 dll      internal static extern int EnumChildWindows  IntPtr hWndParent  EnumChildWindowsCallBack lpEnumFunc  IntPtr lParam      private bool EnumChildWindowsCallBackFunction IntPtr hWnd  IntPtr lparam          if  hWnd    IntPtr Zero                          IntPtr readonlyValue     m readOnly     new IntPtr  1     IntPtr Zero               SendMessage  hWnd  EM SETREADONLY  readonlyValue  IntPtr Zero                 comboBox1 Invalidate                 return true                  return false     private void MakeComboBoxReadOnly  bool readOnly         m readOnly   readOnly      EnumChildWindowsCallBack callBack   new EnumChildWindowsCallBack this EnumChildWindowsCallBackFunction        EnumChildWindows  comboBox1 Handle  callBack  IntPtr Zero

User · Answer

I was hoping to find a solution to this as well  I see that this is an older post  but hoping my approach might simplify this problem for someone else   I was using a combobox with a drop down style of DropDownList  but this should work with other styles  In my case I wanted the text to read  Select Source  and I wanted the other options to be  File  and  Folder   comboBox1 Items AddRange new string     Select Source    File    Folder      comboBox1 Text    Select Source     You can select the 0 index instead if you like  I then removed the  Select Source  item when the index is changed as it no longer matters if that text is visible   comboBox1 SelectedIndexChanged    new EventHandler comboBox1 IndexChanged    private void comboBox1 IndexChanged object sender  EventArgs e                comboBox1 Items Remove  Select Source            if  comboBox1 SelectedIndex    -1                        if  comboBox1 SelectedIndex    0     File                                  Do things                           else if  comboBox1 SelectedIndex    1     Folder                                  Do things                                 Thanks

User · Answer

I realize this is an old thread  but just wanted to let others who might search for an answer to this question know  in the current version of Visual Studio  2015   there is a property called  Placeholder Text  that does what jotbek originally asked about  Use the Properties box  under  Common  properties

User · Answer

Unfortunately none of the above worked for me  so instead I added a label on top of the comboxbox that says  Please select   I used the following code to show and hide it    When I initialise my combobox  if there is no selected value I bring it to the front and set the text   PleaseSelectValueLabel BringToFront    PleaseSelectValueLabel Text   Constants AssessmentValuePrompt   If there is a value selected I send it to the back   PleaseSelectValueLabel SendToBack     I then use the following events to move the label to the front or back depending on whether the user has selected a value   private void PleaseSelectValueLabel Click object sender  EventArgs e        PleaseSelectValueLabel SendToBack        AssessmentValue Focus       private void AssessmentValue Click object sender  EventArgs e        PleaseSelectValueLabel SendToBack         if the user hasnt selected an item  make the please select label visible again private void AssessmentValue Leave object sender  EventArgs e        if  AssessmentValue SelectedIndex  lt  0                PleaseSelectValueLabel BringToFront

User · Answer

private void comboBox1 TextChanged object sender  EventArgs e                if  comboBox1 Text                    comboBox1 Text    Select one of the answers            should do the trick at startup this line is present  when selected an item on combobox  this items text will appear  when deleling the text this text will appear again

User · Answer

If none of the previous solution are working for you  why not add some validation on combobox something like        var orginalindex   0       private void comboBox1 SelectedItemChanged object sender  EventArgs e                if  comboBox1 SelectedIndex    0                        comboBox1 Text    Select one of the answers               comboBox1 SelectedIndex   comboBox1 SelectedIndex                    else                       orginalindex   comboBox1 SelectedIndex

User · Answer

if ComboBoxStyle is set to DropDownList then the easiest way to make sure the user selects an item is to set SelectedIndex   -1  which will be empty

User · Answer

Use the insert method of the combobox to insert the  Please select item  in to 0 index    comboBox1 Items Insert 0   Please select any value      and add all the items to the combobox after the first index  In the form load set   comboBox1 SelectedIndex   0    EDIT   In form load write the text in to the comboBox1 Text by hardcoding  comboBox1 Text    Please  select any value     and in the TextChanged event of the comboBox1 write the following code   private void comboBox1 TextChanged object sender  EventArgs e                        if  comboBox1 SelectedIndex  lt  0                                comboBox1 Text    Please  select any value                             else                               comboBox1 Text   comboBox1 SelectedText

User · Answer

Make the Dropdownstyle property of combo box to Dropdown and set the combo box text to  Select  as below                 combobox DataSource   dsIn Tables 0               combobox DisplayMember    Name               combobox ValueMember    Value               combobox Text    --Select--

User · Answer

I could not get  Andrei Karcheuski  s approach to work but he inspired me to this approach   I added the Localizable Property so the Hint can be translated through  resx files for each dialog you use it on    public partial class HintComboBox   ComboBox       string hint      Font greyFont        Localizable true       public string Hint               get   return hint            set   hint   value  Invalidate                 public HintComboBox                 InitializeComponent               protected override void OnCreateControl                 base OnCreateControl             if  string IsNullOrEmpty Text                         this ForeColor   SystemColors GrayText              Text   Hint                    else                       this ForeColor   Color Black                       private void HintComboBox SelectedIndexChanged object sender  EventArgs e                if  string IsNullOrEmpty Text                          this ForeColor   SystemColors GrayText              Text   Hint                    else                       this ForeColor   Color Black

[c#] How to show text in combobox when no item selected?

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