使用ASP.net C＃从html选择列表中获取所有项目

Question

I have the following select list:

<select name="Context" id="Context" size="5">
<option>Context1</option>
<option>Context2</option>
<option>Context3</option>
<option>Context4</option>
<option>Context5</option>
</select>

I am using javascript to move the items of this select list up and down (this is working). I would like to feed the resulting order back to ASP.net using C#.

If I use the following line of code I get only the selected item, how do I get the whole list?

 string items = Request.Form["Context"];

Answer 1

You can get all items like this.

var ddlArray= new Array();
var ddl = document.getElementById('Context');
for (i = 0; i < ddl.options.length; i++) {
    ddlArray[i] = ddl .options[i].value;
}

Now pass this JavaScript array to your code behind.

Answer 2

One answer is to modify the select to make it a ListBox and then access it programattically on the server:

<asp:ListBox runat="server" name="lstContext" id="lstContext" size="5">
    <asp:ListItem>Context1</asp:ListItem>
    <asp:ListItem>Context2</asp:ListItem>
    <asp:ListItem>Context3</asp:ListItem>
    <asp:ListItem>Context4</asp:ListItem>
    <asp:ListItem>Context5</asp:ListItem>
</asp:ListBox>

Note that I renamed it lstContext as calling it Context will cause build failures (due to sharing a name with the existing Context object).

Then in your code, to access the values in the order they appear:

for (int i = 0; i < lstContext.Items.Count; i++)
{
    string item = lstContext.Items[i].Value;
    // Do something with it
}

Your javascript should still work on the ListBox as it does for the select , so this should remain unaffected.

Answer 3

create a hidden field (runat=server) and store the shuffled <options> into the hidden field; You can access content of hidden field at server side by string itemsOrderedChanged = Request.Form[<HiddenFieldId>];

Answer 4

try to pass JavaScript value to hidden field like this .

var hidden=document.getElementById('hidValue');
var string strValues="";
for(var i=0i<ddlArray.Length;i++){
 strValues+=ddlArray[i]+",";
}

hidden.value=strValues;

And in page_load or what_ever event get this string and split it.

protected HtmlControls.HtmlInputHidden hidValue;

protected void Page_Load(object sender, System.EventArgs e)
{
   dynamic hiddenValue = hidValue.Value;
   string [] arr=hiddenValue.Split(",");
}