ListItems attributes in a DropDownList are lost on postback?

Question

A coworker showed me this:

He has a DropDownList and a button on a web page. Here's the code behind:

protected void Page_Load(object sender, EventArgs e)     {         if (!IsPostBack)         {             ListItem item = new ListItem("1");             item.Attributes.Add("title", "A");              ListItem item2 = new ListItem("2");             item2.Attributes.Add("title", "B");              DropDownList1.Items.AddRange(new[] {item, item2});             string s = DropDownList1.Items[0].Attributes["title"];         }     }      protected void Button1_Click(object sender, EventArgs e)     {         DropDownList1.Visible = !DropDownList1.Visible;     } 

On the page load, the items' tooltips are showing, but on the first postback, the attributes are lost. Why is this the case, and are there any workarounds?

Answer 1

I had the same problem and wanted to contribute this resource where the author created an inherited ListItem Consumer to persist attributes to ViewState. Hopefully it will save someone the time I wasted until I stumbled on it.

protected override object SaveViewState() {     // create object array for Item count + 1     object[] allStates = new object[this.Items.Count + 1];      // the +1 is to hold the base info     object baseState = base.SaveViewState();     allStates[0] = baseState;      Int32 i = 1;     // now loop through and save each Style attribute for the List     foreach (ListItem li in this.Items)     {         Int32 j = 0;         string[][] attributes = new string[li.Attributes.Count][];         foreach (string attribute in li.Attributes.Keys)         {             attributes[j++] = new string[] {attribute, li.Attributes[attribute]};         }         allStates[i++] = attributes;     }     return allStates; }  protected override void LoadViewState(object savedState) {     if (savedState != null)     {         object[] myState = (object[])savedState;          // restore base first         if (myState[0] != null)             base.LoadViewState(myState[0]);          Int32 i = 1;         foreach (ListItem li in this.Items)         {             // loop through and restore each style attribute             foreach (string[] attribute in (string[][])myState[i++])             {                 li.Attributes[attribute[0]] = attribute[1];             }         }     } }