Asp.net mvc 剑道下拉列表casecadefrom

我有三个剑道下降列表如下

(一)

(二)

(三)

---

在这里，我的第三个DDL加载基于第一个和第二个DDL。但有时第二个DDL可能没有值。它可以为空。第一个DDL始终具有值。我的问题是，当第二个DDL为空值时，我的第三个DDL没有加载。但我想总是加载我的第三个DDL。因为SemesterID是必需的。SemesterID取决于programmeID或/和SpecializationID。这就是为什么有时第二个DDl可能有空值。

我使用Ajax调用解决了这个问题。我使用了第二个DDl级联事件Handel，如下所示 .Events（m=>m.Cascade（“cascadesp”））

现在我的第二个DDL

@(Html.Kendo().DropDownListFor(m => m.SpecializationID)

    .HtmlAttributes(new { data_value_primitive = "true" })
    .Name("SpecializationID") 
    .DataTextField("SpecializationNameID") 
    .DataValueField("SpecializationID")
    .OptionLabel("Select Below...")
            .DataSource(source =>
            {

                source.Read(read =>
                {
                    read.Action("GetSpecialization", "Subject").Data("filterSpecialization"); 
                })

                .ServerFiltering(true); 
            })
    .Events(m=>m.Cascade("cascadesp"))
    .SelectedIndex(0)
    .CascadeFrom("ProgrammeID")
)

我的ajax调用是

function cascadesp()
{
    getSemesterID($("#ProgrammeID").data("kendoDropDownList").value(),$("#SpecializationID").data("kendoDropDownList").value(),$("#SpecializationLevelID").data("kendoDropDownList").value(),$("#IntakeID").data("kendoDropDownList").value(),$("#intakeYear").val());
}

function getSemesterID(ProgrammeID, SpecializationID, SpecializationLevelID, IntakeID, intakeYear)
{
    var ddl = $('#SemesterID').data("kendoDropDownList");
    var URL = "/StudentRSRegistration/GetSemester/";
    $.ajax({
        url: URL,
        data: JSON.stringify({ ProgrammeID: ProgrammeID, SpecializationID: SpecializationID, SpecializationLevelID: SpecializationLevelID, IntakeID: IntakeID, intakeYear: intakeYear }),
        async: false,
        cache: false,
        type: "POST",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (data) {
            ddl.setDataSource(data);
        }
    });
}

---

现在，我的semeterd DDL正确地显示了

我认为这个小部件不知道如何从一个下拉列表中处理多个级联。您必须手动处理来自逻辑的级联

 @(Html.Kendo().DropDownListFor(m => m.SemesterID)

.HtmlAttributes(new { data_value_primitive = "true" })
.OptionLabel("Select Below...")
.Name("SemesterID") 
.DataTextField("SemesterName") 
.DataValueField("SemesterID")
        .DataSource(source =>
        {
            source.Read(read =>
            {
                read.Action("GetSemester", "StudentRSRegistration").Data("loadSemester");
            })  

            .ServerFiltering(true); 
        })
.SelectedIndex(0) 
.CascadeFrom("SpecializationID")    
.CascadeFrom("ProgrammeID"`enter code here`)        
)

@(Html.Kendo().DropDownListFor(m => m.SpecializationID)

    .HtmlAttributes(new { data_value_primitive = "true" })
    .Name("SpecializationID") 
    .DataTextField("SpecializationNameID") 
    .DataValueField("SpecializationID")
    .OptionLabel("Select Below...")
            .DataSource(source =>
            {

                source.Read(read =>
                {
                    read.Action("GetSpecialization", "Subject").Data("filterSpecialization"); 
                })

                .ServerFiltering(true); 
            })
    .Events(m=>m.Cascade("cascadesp"))
    .SelectedIndex(0)
    .CascadeFrom("ProgrammeID")
)

function cascadesp()
{
    getSemesterID($("#ProgrammeID").data("kendoDropDownList").value(),$("#SpecializationID").data("kendoDropDownList").value(),$("#SpecializationLevelID").data("kendoDropDownList").value(),$("#IntakeID").data("kendoDropDownList").value(),$("#intakeYear").val());
}

function getSemesterID(ProgrammeID, SpecializationID, SpecializationLevelID, IntakeID, intakeYear)
{
    var ddl = $('#SemesterID').data("kendoDropDownList");
    var URL = "/StudentRSRegistration/GetSemester/";
    $.ajax({
        url: URL,
        data: JSON.stringify({ ProgrammeID: ProgrammeID, SpecializationID: SpecializationID, SpecializationLevelID: SpecializationLevelID, IntakeID: IntakeID, intakeYear: intakeYear }),
        async: false,
        cache: false,
        type: "POST",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (data) {
            ddl.setDataSource(data);
        }
    });
}