根据第一个ddl绑定第二个ddl

Question

我有一个页面，其中有一个LeagueDDL，一个ClubDDL，然后是玩家列表。我想实现的是，用户将选择联赛，然后根据联赛ID将俱乐部绑定到第二个DDL，当用户也选择俱乐部时，根据ClubID将球员列表绑定到View。

到目前为止，我有以下内容：-

视图：-

<script type="text/javascript">
function populateClubsDropdown() {
    $("#ddlClubs").empty();
    var typeID = getLeagueID();
    $.getJSON('@Url.Action("GetClubsByLeague", "Footballer")?TypeID=' + typeID, function (result) {
        $.each(result, function () {
            $("<option>").attr("value", this.ClubID).text(this.Club).appendTo("#ddlClubs");
        });
    });
}
function getLeagueID() {
    var leagueID = $("#ddlLeagues").val();
    return leagueID;
}
</script>

@Html.DropDownListFor(model => model.League.LeagueID, Model.LeagueList, 
    new { id = "ddlLeagues", onChange = "$:populateClubsDropdown()" })
@Html.DropDownListFor(model => model.Club.ClubID, Model.ClubList, new { id = "ddlClubs" })

在我的控制器中，我有：-

        public ViewResult Index()
    {
        League league = new League();
        string selected = "Please Select";
        model.LeagueList = model.PopulateLeagueDDL(selected, league, null);
        Club club = new Club();
        model.ClubList = model.PopulateClubDDL(selected, league, club, null);
        model.Footballers = db.Footballers.Include("Club").Include("Position").Include("Status").Include("Country");
        return View(model);
    }
       public JsonResult GetClubsByLeague(int LeagueID)
    {
        var result = footballersDAL.GetClubsByLeagueId(LeagueID).Select(
                c => new { ClubID = c.ClubID, Club = c.ClubName });
        JsonResult jsonResult = new JsonResult { Data = result, JsonRequestBehavior = JsonRequestBehavior.AllowGet };
        return jsonResult;
    }

当我第一次启动页面时，两个Dropdown都是正确的，但是当我更改LeagueDDL时，我会得到一个空的第二个DDL。Json断点没有被击中。

我很感激在这方面能得到一些帮助，我不太明白我做错了什么。

更新以查看

<script type="text/javascript">
function populateClubsDropdown() {
    $("#ddlClubs").empty();
    var typeID = getLeagueID();
    $.getJSON('@Url.Action("GetClubsByLeague", "Footballer")?TypeID=' + typeID, function (result) {
        $.each(result, function () {
            $("<option>").attr("value", this.ClubID).text(this.Club).appendTo("#ddlClubs");
        });
    });
}
function getLeagueID() {
    var leagueID = $("#ddlLeagues").val();
    return leagueID;
$(function () {
        $('#ddlLeagues').change(populateClubsDropdown);
    });
}

@Html.DropDownListFor(model => model.League.LeagueID, Model.LeagueList,
            new { id = "ddlLeagues" })
@Html.DropDownListFor(model => model.Club.ClubID, Model.ClubList, new { id = "ddlClubs" })

Answer 1

看起来问题就在这里：

@Html.DropDownListFor(model => model.League.LeagueID, Model.LeagueList, 
new { id = "ddlLeagues", onChange="$:populateClubsDropdown()" }) //What is"$:"?!

更改为：

@Html.DropDownListFor(model => model.League.LeagueID, Model.LeagueList, 
new { id = "ddlLeagues", onChange = "populateClubsDropdown()" })

使用jQuery不引人注目的事件侦听器是更好的事件：

 <script>    
    function populateClubsDropdown() {
        $("#ddlClubs").empty();
        var typeID = getLeagueID();
        $.getJSON('@Url.Action("GetClubsByLeague", "Footballer")?TypeID=' + typeID, function (result) {
            $.each(result, function () {
                $("<option>").attr("value", this.ClubID).text(this.Club).appendTo("#ddlClubs");
            });
        });
    }
    $(function(){
        $('#ddlLeagues').change(populateClubsDropdown);
    });
</script>
@Html.DropDownListFor(model => model.League.LeagueID, Model.LeagueList, 
new { id = "ddlLeagues"})
@Html.DropDownListFor(model => model.Club.ClubID, Model.ClubList,
 new { id = "ddlClubs" })

---

更新：看起来您向操作发送了错误的参数：
应该是LeagueID，但您发送TypeId~