When I set the DropDownList.SelectedIndex of ONE DropDownList they ALL change!

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S_K - 13 Nov 2007 23:39 GMT

Hi,

I have a list of 6 DropDownList boxes, from DropDownList1 to
DropDownList6, and I'm changing the SelectedIndex of each using a
foreach loop as follows:

foreach(PaymentReqDisplay thispayment in listPaymentReqDisplay)
{
if ((string)thispayment.TaxType == "FIT")
this.DropDownList1.SelectedIndex =
(int)thispayment.PaymentRequirementID - 1;
if ((string)thispayment.TaxType == "FUI")
this.DropDownList2.SelectedIndex =
(int)thispayment.PaymentRequirementID - 1;
if ((string)thispayment.TaxType == "SIT")
this.DropDownList3.SelectedIndex =
(int)thispayment.PaymentRequirementID - 1;
if ((string)thispayment.TaxType == "SUI")
this.DropDownList4.SelectedIndex =
(int)thispayment.PaymentRequirementID - 1;
if ((string)thispayment.TaxType == "ETF")
this.DropDownList5.SelectedIndex =
(int)thispayment.PaymentRequirementID - 1;
if ((string)thispayment.TaxType == "SDI")
this.DropDownList6.SelectedIndex =
(int)thispayment.PaymentRequirementID - 1;
}

The problem is that when I change, say, DropDownList4.SelectedIndex =
3; every other DropDownList's SelectedIndex changes as well!?

What am I doing wrong?

Thanks much for your help.
Steve

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Eliyahu Goldin - 14 Nov 2007 09:52 GMT

Do all ddls share the same items?

When you set the SelectedIndex property, it actually sets the Selected
property of the item you select. Thus the same item becomes selected in all
ddls it is participating.

The solution is to replicate the item collection for every single ddl.

Signature

Eliyahu Goldin,
Software Developer
Microsoft MVP [ASP.NET]
http://msmvps.com/blogs/egoldin
http://usableasp.net

> Hi,
>
[quoted text clipped - 31 lines]
> Thanks much for your help.
> Steve

Reply to this Message

S_K - 14 Nov 2007 15:29 GMT

On Nov 14, 2:52 am, "Eliyahu Goldin"
<REMOVEALLCAPITALSeEgGoldD...@mMvVpPsS.org> wrote:

> Do all ddls share the same items?
>
[quoted text clipped - 46 lines]
>
> - Show quoted text -

So you are saying that by setting the SelectIndex of (say) the first
ddl ALL of the ddls in that group get set along with it?
So how do I replicate the item collection for every single ddl? I
don't understand what you mean. Could you give me a code example?

Thanks so much for your help.
Steve

Reply to this Message

Eliyahu Goldin - 14 Nov 2007 16:16 GMT

I mean every ddl should have it's own item collection, not shared with the
other ddls.

How do you populate the ddls?

Signature

Eliyahu Goldin,
Software Developer
Microsoft MVP [ASP.NET]
http://msmvps.com/blogs/egoldin
http://usableasp.net

> On Nov 14, 2:52 am, "Eliyahu Goldin"
> <REMOVEALLCAPITALSeEgGoldD...@mMvVpPsS.org> wrote:
[quoted text clipped - 58 lines]
> Thanks so much for your help.
> Steve

Reply to this Message

S_K - 14 Nov 2007 16:32 GMT

> On Nov 14, 2:52 am, "Eliyahu Goldin"
>
[quoted text clipped - 63 lines]
>
> - Show quoted text -

I FOUND THE PROBLEM!!!

This is what happend.
In my code I called a method to fill the Items value for each
DropDownList using a ListItem as in the code:

for (int i = 0; i < listPaymentReq.Count; i++)
{
ListItem li = new
ListItem(listPaymentReq[i].Payment_Req_Code.ToString(),
listPaymentReq[i].Payment_Req_ID.ToString());

DropDownList1.Items.Insert(i, li);
DropDownList2.Items.Insert(i, li);
DropDownList3.Items.Insert(i, li);
.
.
. }

Note that the "li" is a pointer and I'm inserting the SAME Items value
into each ddl! This apparently means that the SelectedIndex for each
ddl is also a pointer pointing to the same location as well.

You learn something new everyday.

thanks for the help.

Steve

Reply to this Message

Eliyahu Goldin - 14 Nov 2007 16:51 GMT

> This apparently means that the SelectedIndex for each
> ddl is also a pointer pointing to the same location as well.

SelectedIndex is not a pointer, it is a property and when you set or get it,
some code runs.

When you "set" it, asp.net goes to the Items collection and mark the item as
"Selected" be setting li.Selected = true.

When you "get" the SelectedIndex on another ddl, asp.net goes to the Items
collection, finds the item with Selected=true and returns it's index. This
causes the effect you observed and successfully fixed.

Signature

Eliyahu Goldin,
Software Developer
Microsoft MVP [ASP.NET]
http://msmvps.com/blogs/egoldin
http://usableasp.net

>> On Nov 14, 2:52 am, "Eliyahu Goldin"
>>
[quoted text clipped - 94 lines]
>
> Steve

Reply to this Message

When I set the DropDownList.SelectedIndex of ONE DropDownList they ALL change!

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