如何将SelectList的选定值传递给我的Action？

Question

In my ASP.NET MVC 4 project I have a View that has this piece:

    <td>
         @Html.DropDownList("SelectedValue", ViewBag.SoftwaresList as SelectList, "Add New Software")
    </td>
    <td>
        No Description
    </td>
    <td>
        @Html.ActionLink("Add", "AddSoftware", new { pDeviceId = Model.Id, pSoftwareId =  Model.SelectedValue})
    </td>

My Model has an object property "SelectedValue". What I am trying to do is, when a user clicks the Link Add, I pass the Device Id (works fine, because this is straight from the Model being passed into the the View) AND the Selected Id from the DropDownList. The DropDownList is a collection of a different Model, but it contains an Id as well.

I've tried the following with no luck:

@Html.ActionLink("Add", "AddSoftware", new { pDeviceId = Model.Id, pSoftwareId = 
      ((ViewBag.SoftwaresList as SelectList).SelectedValue as SoftwareModel).Id})

It's worth noting: The DropDownList is populated with my SoftwareModel's correctly, however, I am having no luck passing that additional value from the selected value to to the Action in the Controller.

In fact, what I see in Chrome hover over is:

someURL\\AController\\AddSoftware?pDeviceId=2

Where I would expect it to be something like:

someURL\\AController\\AddSoftware?pDeviceId=2&pSoftwareId=5

Answer 1

It is easiest to have the list in a form (with @Html.BeginForm or @Ajax.BeginForm) and have the Button be the submit button for that form. The controller action method can define an input parameter of the model you are trying to submit or just the ID itself. In that case the browser and the framework will do all the work for you.

@using (
        Ajax.BeginForm
            (
               "MyAction",
                "MyController",
                new {Param1 = value1, param2 = value2 },
                new AjaxOptions
                    {
                        OnSuccess = "javascriptForSuccess",
                        UpdateTargetId = "DivToUpdate",
                        OnFailure = "javascriptForFailure",
                        InsertionMode = InsertionMode.Replace,
                        HttpMethod = "POST",
                    }
            )
        )
{
    <td>
         @Html.DropDownList("SelectedValue", ViewBag.SoftwaresList as SelectList, "Add New Software")
    </td>
    <td>
        No Description
    </td>
    <td>
        <input type="submit" id="Btn_Create" name="Btn_Create" value="Create" />
    </td>
}

Answer 2

You are creating that action link on the server and sending HTML to client. The user selects a value from drop down on client which means it is not available when you create HTML for your Add link (ie @Html.ActionLink("Add" )

You should, instead, create a form and post values to server to get selected value

Or

You can use JavaScript to get selected value from link and send it to server when the link gets clicked.

Answer 3

尝试这个

@Html.DropDownListFor(m => m.pDeviceId , (SelectList)ViewBag.SoftwaresList, new { onchange = "document.location.href = 'AddSoftware?pDeviceId=' + this.options[this.selectedIndex].value;" })

Answer 4

Your best option is to turn this into a form by using the following HTML and Controller setup. You will also have to change ViewBag.SoftwaresList into a List<SelectListItem>()

HTML:

@using(Html.BeingForm())
{
<td>
     @Html.DropDownListFor(x => x.SelectedValue, ViewBag.SoftwaresList as List<SelectListItem>, "Add New Software")
</td>
<td>
    No Description
</td>
<td>
    @Html.ActionLink("Add", "AddSoftware", new { pDeviceId = Model.Id, pSoftwareId =  Model.SelectedValue})
</td>
}

Controller:

[HttpPost]
public ActionResult(MyModel model)
{
    //Logic Code Goes Here
    return View(model);
}

Select List: Here is how you can create a select list. Note how I do not use the 'Selected' parameter, this will be automatically calculated for you so there is no need

var selectList = new List<SelectListItem>();
selectList.Add(new SelectListItem
{
    Text = "Name",
    Value = "ID"
});