Binding array + one object to Dropdownlist

Question

I have an array of type Person, which contains string objects: FirstName, LastName, login.

I have this bound to a dropdownlist.

Now along with this array, I also want to display one more item called "Desk". How can i do that?

My current code is:

Person[] traders = GetTraders();
ddl_trader.Items.Clear();
ddl_trader.DataSource = traders;
ddl_trader.DataTextField = "LastName";
ddl_trader.DataValueField = "Login";
ddl_trader.DataBind();

I also want that one extra item I'm adding to be the default selected item.

What is "Desk" ? A property of Person ? An independent object with a link to Person ? — Matthieu
– Matthieu, Commented Oct 12, 2010 at 20:36

lincolnk · Accepted Answer · 2010-10-12 21:01:52Z

3

You can set the AppendDataBoundItems property to true (it's false by default), add your item manually, then do the databinding process to add the remaining items. AppendDataBoundItems determines if the list is cleared during databinding or not.

ddl_trader.Items.Clear();
ddl_trader.AppendDataBoundItems = true;
ddl_trader.Items.Add("Desk");
ddl_trader.DataTextField = "LastName";
ddl_trader.DataValueField = "Login";
ddl_trader.DataSource = traders;
ddl_trader.DataBind();

if you need to add the new item after the list has been bound, you can do

ddl_trader.Items.Insert(0, "Desk");

this does not require setting AppendDataBoundItems to true.

edited Oct 12, 2010 at 21:01

answered Oct 12, 2010 at 20:55

lincolnk

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Comments

Anthony Pegram · Accepted Answer · 2010-10-12 20:31:48Z

1

One such method is to load the result of GetTraders() into a List<Person>. You can then add one or many new Person objects to the list before binding it to your dropdown.

List<Person> traders = new List<Person>(GetTraders());
traders.Add(new Person() { LastName = "Foo", Login = "Bar" });
ddl_trader.DataSource = traders;

You could also define an additional array and concatenate that to the result instead of creating a combined collection. (Note: this would be two distinct arrays treated as a single sequence, however the backing arrays would still be seperate).

Person[] traders = GetTraders();
Person[] moreTraders = new Person[] { new Person() { LastName = "Foo", Login = "Bar" } };
ddl_trader.DataSource = traders.Concat(moreTraders);

answered Oct 12, 2010 at 20:31

Anthony Pegram

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4 Comments

Ayush Over a year ago

I was wondeing if it could be done without adding it to the list. Since, it is really just a string "Desk" and doesn't need a FirstName, Lastname etc.

Ayush Over a year ago

Gotcha. If I can't figure out a way to do it without creating another array of Person class, I'll use your second method.

Ayush Over a year ago

For some reason, traders.Concat returns an error. Is there some assembly or reference I need to use Concat?

Anthony Pegram Over a year ago

@xbonez, It's an extension method of IEnumerable<T> from .NET 3.5+, C# 3.0+. If you are on a compatible platform (think: Visual Studio 2008 or 2010), you'd need a reference to System.Core.dll and a using System.Linq; statement in your code-behind. If you are on a prior version of .NET, try the first approach (VS 2005+, using System.Collections.Generic;).

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