使用MVC4传递值的Java脚本

Question

我的Create视图是这样的：

@model ContactProject.Models.Activity.Activity
@{
ViewBag.Title = "Create";
IEnumerable<ContactProject.Models.Activity.Activity> activities = ViewBag.Activities;
}
    <div class="editor-label">
        @Html.Label("Project")
    </div>
    <div class="editor-field">
       @Html.DropDownList("Projects", ViewBag.Project as SelectList,"----Project----", new { id = "ProjectsID" })
       @Html.ValidationMessageFor(model => model.iProjectID)
    </div>
    <div class="editor-label">
        @Html.Label("Title")
    </div>
    <div class="editor-field" id="TitlesDivID">
        <select id="TitlesID" name="Titles"></select>
    </div>
// other codes...
if (activities !=null){
// Display activities.
}

这是我的JS代码

$('#ProjectsID').change(function () {
        var URL = 'TitleList';          
        $.getJSON(URL + '/' + $('#ProjectsID').val(), function (data) {
            var items = '<option>Select a Title</option>';
            $.each(data, function (i, title) {
                items += "<option value='" + title.Value + "'>" + title.Text + "</option>";
            if (items != null)
            {
                var addValue = $('#ProjectsID').val();             
                $.ajax
                ({ 
                    type: "POST",
                    url: "/Activity/getCreateActivities",
                    data: { projectID: addValue },
                    success: function (@ViewBag.Activities) {
                    }
                })
            }
        })    

基本上，我想用这个JS实现我的函数，不仅显示与项目相关的标题，而且显示所有活动都有相同的项目名称。

这就是为什么我在jquery回调函数中写“成功:函数(@ViewBag.Activities)”的原因。

下面是我的控制器中的方法：

public ActionResult getCreateActivities(string projectID) 
    {
    int iProjectID = Int32.Parse(projectID);
    ViewBag.Project = GetProjects();
    var Activities = (from a in db.Activities
                     where a.iProjectID == iProjectID
                     select a).ToList();
    ViewBag.Activities = Activities;
    return View("Create");
    }

但是当我使用断点进行调试时，会返回带有值和计数的@ViewBag.Activities，但似乎没有显示在我的屏幕上，有人对此有任何想法吗？如有任何贡献，将不胜感激。

更新：

<table>
@foreach (var item in Activities) {
<tr>
    <td>
        @Html.DisplayFor(modelItem => item.ProjectID)
    </td>
    <td>
        @Html.DisplayFor(modelItem => item.Project.ProjectName)
    </td>
</tr>

Answer 1

如果使用ajax请求在ViewBag中设置一些值，则不会得到它。处理此问题的常规方法是，以JSON格式返回数据并访问它。

public ActionResult getCreateActivities(string projectID) 
{
    int iProjectID = Int32.Parse(projectID);        
    var Activities = (from a in db.Activities
                 where a.iProjectID == iProjectID
                 select a).ToList();

    return Json(new { Projects : GetProjects(),
                      Activities : Activities } ,JsonRequestBehaviour.AllowGet);
}

上面的内容将返回一个匿名对象的JSON表示，如下所示

{
    "Projects": [ { "Id": 2 } ],
    "Activities": [ { "id": 113,"Name": "My name" } ]
}

在ajax方法的成功回调中，访问它就像

success(function(data){
   // now you can acceess data.Projects and data.Activities
}