CODEWITHSUNDEEP
c#asp.netlistbox
Silvia Stoyanova
Silvia Stoyanova

Reputation: 281

Can't get my listbox to display objects

Hello everyone I've been trying to put some objects in an ASP.NET list box but it's just not working.

I do have an overridden ToString method so I can't understand why this statement won't work. Here's the code that I use:

for (int i = 0; i < fitnessClassList.Count(); i++)
{
    lbDisplayItems.Items.Add(fClassList.getFClass(i));
}

And the errors that I get:

Error   2   Argument 1: cannot convert from 
                    'FitClassManage' to 
                    'System.Web.UI.WebControls.ListItem'    

Error   1   The best overloaded method match for 
                    'System.Web.UI.WebControls.ListItemCollection.Add(System.Web.UI.WebControls.ListItem)' 
                    has some invalid arguments

Upvotes: 1

Views: 2102

Answers (4)

John Moore
John Moore

Reputation: 181

Sounds like you want to display a "custom" item in a list box. I got it to work doing the following:

  • I created a usercontrol that had the controls I wanted named MyListItem. In my case I wanted a checkbox and textfield.
  • I created a new myListBox that inherited from ListBox and created an Add method. This method did the following:
  • It had one string argument for text to be displayed
  • It created an instance of MyListItem and assigned the text string to its Text property.
  • I assigned an event handler to respond to the checkBox check event.
  • I added my custom item to the myListBox.controlls.

When I programatically added items to myListBox, my custom items were displayed!!

Upvotes: 1

Adriano Repetti
Adriano Repetti

Reputation: 67080

The ASP.NET ListBox is not like the WinForms ListBox. You cannot add any object to him. Its item collection (ListItemCollection) is limited to ListItem (so you can't add your business objects relying on ToString() for visualization).

Use this code:

ListItem listItem = new ListItem(fitnessClassList.getFitnessClass(i).ToString());
lbDisplayItems.Items.Add(listItem);

Do not forget that if you'll use that ListItem you won't have the object but its display name (the result of ToString()). See the link about the ListItem for more details.

As alternative you may set the DataSource of the ListView to your fitnessClassList (if it supports that in any way, see this overview on MSDN).

Upvotes: 2

mellodev
mellodev

Reputation: 1607

You need to use the .DataSource and .DataBind properties on the listbox.

lbDisplayItems.DataSource = fitnessClassList;
lbDisplayItems.DataBind();

Check out this link for a small example http://asp-net-example.blogspot.com/2011/10/how-to-databind-listbox-using-stack.html

Upvotes: 0

Tomas Voracek
Tomas Voracek

Reputation: 5914

Method Add expects ListItem object (or string, see links below), but you are passing a custom class.

You probably want following:

lbDisplayItems.Items.Add(new ListItem(fitnessClassList.getFitnessClass(i).ToString()));

See http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listitemcollection.aspx - there are only 2 "Add" methods.

See http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listitem.aspx for available constructors.

Upvotes: 0

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