Copy Code code as follows:
<asp:dropdownlist id= "DDL1" runat= "Server" width= "100px" ></asp:DropDownList>
<asp:dropdownlist id= "DDL2" runat= "Server" width= "100px" ></asp:DropDownList>
<asp:dropdownlist id= "DDL3" runat= "Server" width= "100px" ></asp:DropDownList>
Js:
Copy Code code as follows:
<script src= "Js/jquery-1.4.2.min.js" type= "Text/javascript" ></script>
<script type= "Text/javascript" >
$ (document). Ready (function () {
Geta ();
$ ("#ddl1"). Change (function () {GETB ();});
$ ("#ddl2"). Change (function () {getc ();});
});
function Geta ()
{
$ ("#ddl1"). HTML ("");
$ ("#ddl1"). Append ("<option value= '-1 ' selected= ' selected ' > Please select ...</option>");
$ ("SELECT[NAME$=DDL1] > option:selected"). Remove ();
var Strid = 0;
$.getjson ("loadclass.ashx?ddlid=" + Strid, function (data) {
for (var i = 0; i < data.length; i++) {
$ ("SELECT[NAME$=DDL1]"). Append ($ ("<option></option>"). Val (data[i].id). HTML (data[i). Cname));
};
Getb ();
});
}
function Getb ()
{
$ ("#ddl2"). HTML (""); $ ("#ddl3"). HTML ("");
var Strid = $ ("#ddl1"). attr ("value");
if (Strid!= 0) {
$.getjson ("loadclass.ashx?ddlid=" + Strid, function (data) {
for (var i = 0; i < data.length; i++) {
$ ("SELECT[NAME$=DDL2]"). Append ($ ("<option></option>"). Val (data[i].id). HTML (data[i). Cname));
};
Getc ();
});
}
}
function getc ()
{
$ ("#ddl3"). HTML ("");
var Strid = $ ("#ddl2"). attr ("value");
if (Strid!= 0) {
$.getjson ("loadclass.ashx?ddlid=" + Strid, function (data) {
for (var i = 0; i < data.length; i++) {
$ ("select[name$=ddl3]"). Append ($ ("<option></option>"). Val (data[i].id). HTML (data[i). Cname));
};
});
}
}
</script>
LOADCLASS.ASHX:
Copy Code code as follows:
<%@ WebHandler language= "C #" class= "LoadClass"%>
Using System;
Using System.Web;
Using System.Text;
Using System.Data;
public class Loadclass:ihttphandler {
public void ProcessRequest (HttpContext context) {
Array [{"id": "275", "Cname": "A1"},{"id": "319", "Cname": "A2"},{"id": "322", "Cname": "A3"}]
int Strid = Convert.ToInt32 (context. request["Ddlid"]);
String strSQL = "SELECT * from Class where parent_ptr=" + Strid + "ORDER by classorder ASC";
DB D = new db ();
DataTable dt = D.GETDT (strSQL);
StringBuilder strclass = new StringBuilder ();
if (dt!= null)
{
Strclass.append ("[");
for (int i = 0; i < dt. Rows.Count; i++)
{
Strclass.append ("{");
Strclass.append ("\" id\ ": \" "+ dt.) rows[i]["id"]. ToString () + "\", ");
Strclass.append ("\" cname\ ": \" "+ dt.) rows[i]["Classcname"]. ToString () + "\" ");
if (i!= dt. ROWS.COUNT-1)
{
Strclass.append ("},");
}
}
}
Strclass.append ("}");
Strclass.append ("]");
Context. Response.ContentType = "Application/json";
Context. response.contentencoding = Encoding.UTF8;
Context. Response.Write (Strclass.tostring ());
Context. Response.End ();
}
public bool IsReusable {
get {
return false;
}
}
}
Attention:
Copy Code code as follows:
Background can only get value values, can not get text directly, need to pass JS, control relay
Results: 275 276 277
Label1.Text = Request.form[ddl1. UniqueID] + "" + request.form["DDL2"] + "" + request.form[ddl3. Clientid.replace ("_", "$")]; problems encountered: The value of the dropdown box text is passed through the HiddenField control to <asp:hiddenfield id= "HiddenField1" runat= "Server"/ >
<asp:hiddenfield id= "HiddenField2" runat= "Server"/>
<asp:hiddenfield id= "HiddenField3" runat= "Server"/>
Assign the value of the selected Drop-down box to the hidden control: <script type= "Text/javascript" >
var Key1 = $ ("#ddl1 >option:selected"). Val ();
$ (' #HiddenField1 '). Val (Key1);
var Key2 = $ ("#ddl2 >option:selected"). Val ();
$ (' #HiddenField2 '). Val (Key2);
var Key3 = $ ("#ddl3 >option:selected"). Val ();
$ (' #HiddenField3 '). Val (Key3);
</script>
The values that are dynamically assigned to the HiddenField control after you select the Drop-down box cannot correspond to the value that is selected by the Drop-down box!
It may have to do with initialization, where should the assignment of the code go? Or is there any good way to welcome the discussion?
