Extended attributes of listitem in dropdownlist

When the extended attribute attributes is added to the listitem, if the page is sent back, the attribute will be lost. I found it online for half a day and said it was a Microsoft Bug. Finally, I came up with a Bt method: binding every time, then set the selected location

Code
String n = DDL. selectedvalue;
DDL. Items. Clear ();
For (INT I = 0; I <10; I ++)
{
Listitem li = new listitem ();
Li. Text = I;
Li. value = I;
Li. attributes ["ID"] = I;
DDL. Items. Add (LI );
}

DDL. selectedindex = DDL. Items. indexof (DDL. Items. findbyvalue (n ));

 

Compared with other solutions, this solution has a poor performance, but is easy to use.