.net DropDownList静态联动

1.前台

 <span id="spnClient" style="margin-left: 30px; margin-top: 10px">
 <lable>Client: </lable>
 <asp:DropDownList ID="ddlClient" DataValueField="ID" DataTextField="NAME" runat="server" />
 </span>

 <span id="spnProject" style="margin-left: 30px; margin-top: 10px">
 <lable>Project: </lable>
 <asp:DropDownList ID="ddlProject" DataValueField="ID" DataTextField="NAME" runat="server" />
 </span>
 <span id="spnUser" style="display: none; margin-left: 30px; margin-top: 10px;">
 <lable>User: </lable>
 <asp:DropDownList ID="ddlUser" DataValueField="ID" DataTextField="USER_NAME" runat="server" />
 </span>

2.绑定DataSource

        private void LoadDropDownList()
         {
             DataTable dtYear =SplendidCache.Years();
             ddlYEAR.DataSource = dtYear;
             ddlYEAR.DataBind();
             ddlYEAR.SelectedValue = DateTime.Now.Year.ToString();

             DataTable dtClient = SplendidCache.Client(true);
             ddlClient.DataSource = dtClient;
             ddlClient.DataBind();

             DataTable dtProject = SplendidCache.Project();
             ddlProject.DataSource = dtProject;
             ddlProject.DataBind();

             DataTable dtUser = SplendidCache.AssignedUser();
             ddlUser.DataSource = dtUser;
             ddlUser.DataBind();

             BindProjects();
             BindUsers();
         }

         private void BindProjects()
         {
             DataTable dtProjects = new DataTable();
             DbProviderFactory dbf = DbProviderFactories.GetFactory();
             using (IDbConnection con = dbf.CreateConnection())
             {
                 con.Open();
                 using (IDbCommand cmd = con.CreateCommand())
                 {
                     string sSQL = "SELECT ID,NAME,CLIENTID FROM Project WHERE DELETED=0    ORDER BY NAME " + ControlChars.CrLf;
                     cmd.CommandText = sSQL;
                     using (DbDataAdapter da = dbf.CreateDataAdapter())
                     {
                         ((IDbDataAdapter)da).SelectCommand = cmd;
                         da.Fill(dtProjects);
                         StringBuilder sbProjects = new StringBuilder();
                         if (dtProjects != null && dtProjects.Rows.Count > )
                         {
                             sbProjects.Append("{\"project\":[");
                             int i = ;
                             int count = dtProjects.Rows.Count;
                             foreach (DataRow row in dtProjects.Rows)
                             {
                                 if (i == count)
                                 {
                                     sbProjects.Append("{\"client\":\"" + Sql.ToString(row["CLIENTID"]) + "\",\"id\":\"" + Sql.ToString(row["ID"]) + "\",\"name\":\"" + Sql.ToString(row["NAME"]).Replace("'","‘") + "\"}");
                                 }
                                 else
                                 {
                                     sbProjects.Append("{\"client\":\"" + Sql.ToString(row["CLIENTID"]) + "\",\"id\":\"" + Sql.ToString(row["ID"]) + "\",\"name\":\"" + Sql.ToString(row["NAME"]).Replace("'", "‘") + "\"},");
                                 }
                                 i++;
                             }
                             sbProjects.Append("]");
                         }
                         sbProjects.Append("}");
                         m_sProjectsJson = sbProjects.ToString();
                     }
                 }
             }
         }
         private void BindUsers()
         {
             DataTable dtUsers = new DataTable();
             DbProviderFactory dbf = DbProviderFactories.GetFactory();
             using (IDbConnection con = dbf.CreateConnection())
             {
                 con.Open();
                 using (IDbCommand cmd = con.CreateCommand())
                 {
                     string sSQL = "SELECT DISTINCT USER_ID,USER_NAME,PROJECT_ID FROM vwPROJECT_USERS WHERE USER_ID IS NOT NULL GROUP BY USER_ID,USER_NAME,PROJECT_ID ORDER BY USER_NAME" + ControlChars.CrLf;
                     cmd.CommandText = sSQL;
                     using (DbDataAdapter da = dbf.CreateDataAdapter())
                     {
                         ((IDbDataAdapter)da).SelectCommand = cmd;
                         da.Fill(dtUsers);
                         StringBuilder sbUsers = new StringBuilder();
                         if (dtUsers != null && dtUsers.Rows.Count > )
                         {
                             sbUsers.Append("{\"user\":[");
                             int i = ;
                             int count = dtUsers.Rows.Count;
                             foreach (DataRow row in dtUsers.Rows)
                             {
                                 if (i == count)
                                 {
                                     sbUsers.Append("{\"project\":\"" + Sql.ToString(row["PROJECT_ID"]) + "\",\"id\":\"" + Sql.ToString(row["USER_ID"]) + "\",\"name\":\"" + Sql.ToString(row["USER_NAME"]) + "\"}");
                                 }
                                 else
                                 {
                                     sbUsers.Append("{\"project\":\"" + Sql.ToString(row["PROJECT_ID"]) + "\",\"id\":\"" + Sql.ToString(row["USER_ID"]) + "\",\"name\":\"" + Sql.ToString(row["USER_NAME"]) + "\"},");
                                 }
                                 i++;
                             }
                             sbUsers.Append("]");
                         }
                         sbUsers.Append("}");
                         m_sUserJson = sbUsers.ToString();
                     }
                 }
             }
         }

    private static string m_sProjectsJson = "";
         public static string ProjectsJson
         {
             get { return m_sProjectsJson; }
         }

         private static string m_sUserJson = "";
         public static string UsersJson
         {
             get { return m_sUserJson; }
         }

3.javascript

     $("#<%=ddlClient.ClientID%>").change(function () {
             loadproject();
         });
         $("#<%=ddlProject.ClientID%>").change(function () {
             loaduser();
         });

        function loadproject() {
             var client = $("#<%=ddlClient.ClientID%>").val();
             var projectArray = jQuery.parseJSON('<%= ProjectsJson%>');
             var filtered = $.grep(projectArray.project,
                            function (item) {
                                if (client != "") {
                                    return item.client == client;
                                }
                                else {
                                    return item;
                                }
                            }
                        );
             $("#<%=ddlProject.ClientID%>").empty();
             $.each(filtered, function (i, item) {
                 $("#<%=ddlProject.ClientID%>").append("<option value='" + item.id + "'>" + item.name + "</option>");
             });
         }

    function loaduser() {
             var project = $("#<%=ddlProject.ClientID%>").val();
             var userArray = jQuery.parseJSON('<%= UsersJson%>');
             var filtered = $.grep(userArray.user,
                             function (item) {
                                 if (project != "") {
                                     return item.project == project;
                                 }
                                 else {
                                     return item;
                                 }
                             }
                         );
             $("#<%=ddlUser.ClientID%>").empty();
             $.each(filtered, function (i, item) {
                 $("#<%=ddlUser.ClientID%>").append("<option value='" + item.id + "'>" + item.name + "</option>");
             });
         }