Send single value through RouteValueDictionary

Question

One of the properties of my ViewModel is an array which, unfortunately, is null every time I post back to the controller. I figured a simple hack where I place the values into a coma-delimited string.

This works great for our paging plugin, which posts back to our Index method, using a RouteValueDictionary. However, it is not working in the Html.BeginForm helper which posts back to a different controller action (the Update method).

View

@*Since we can't send arrays or complex objects break array down into string for RouteValueDictionary*@
var channelCodes = "";
for (int i = 0; i < Model.searchChannelCode.Length; i++)
{
    channelCodes += Model.searchChannelCode[i];

    if (i + 1 < Model.searchChannelCode.Length)
    {
        channelCodes += ",";
    }
}  

@*The 'searchChannelCodesPagin' variable from this RouteValueDictionary always posts back as null
using (Html.BeginForm("Update", "ZipCodeTerritory", new RouteValueDictionary()
    {
        {"searchChannelCodesPaging", channelCodes }
    }, FormMethod.Post, new {id = "UpdateForm"}))
{
    @Html.HiddenFor(model => model.searchZip)
    @Html.HiddenFor(model => model.searchTerritory)
    @Html.HiddenFor(model => model.searchState)
    @Html.HiddenFor(model => model.searchActiveOnly)
    @Html.HiddenFor(model => model.zipCodeTerritory)

    <div id="cloneBox">
        <div id="rw1">
            @Html.LabelFor(model => model.newTerritory)
            @Html.TextBoxFor(model => model.newTerritory, new { style = "width: 30px;padding-left:10px;", maxLength = 3 })
            @Html.LabelFor(model => model.newDescription)
            @Html.TextBoxFor(model => model.newDescription, new { style = "width: 250px;padding-left:10px;", maxLength = 30 })  
            @Html.LabelFor(model => model.newEffectiveDate)     
            @Html.TextBoxFor(model => model.newEffectiveDate, new { style = "width: 80px;padding-left:10px;" }) 
            <div id="rw2" style="padding-top: 10px;">
                @Html.LabelFor(model => model.newChannelCode)
                @Html.DropDownListFor(model => model.newChannelCode, Model.ChannelCodes, " ")
                @Html.LabelFor(model => model.newStateCode)
                @Html.DropDownListFor(model => model.newStateCode, Model.StateCodes, "  ")
                @Html.LabelFor(model => model.newEndDate)
                @Html.TextBoxFor(model => model.newEndDate, new { style = "width: 80px;" })
            </div>                                 
        </div>
    </div>
    <br/>
    <div id="buttonDiv">
        <button type="submit" id="CloneButton" name="button" value="clone">Apply New Data</button>
        <button type="submit" id="deleteButton" name="button" value="delete">Delete Selected Items</button> 
        <button type="submit" id="removeButton" name="button" value="removeErrors">Remove Selected Errors</button>           
    </div>

}

Controller

The forma above posts to this controller action. The searchChannelCodePaging variable is null each time.

    [HttpPost]
    public ActionResult Update(ZipCodeIndex updateZip, string button, string searchChannelCodesPaging)
    {

Answer 1

Since you are doing a post, the simplest way to get it to the backend would be add a hidden field:

@Html.HiddenFor("searchChannelCodesPaging", searchChannelCodesPaging);

As a routing value, you may need to get it explicitly within the control via one of the two following approaches. These objects are directly accessible within the Controller class.

RouteData.Values("searchChannelCodesPaging")
Request.QueryString.Get("searchChannelCodesPaging");

Answer 2

You don't have to serialize a array type model parameter to a CSV string to get it to post to your controller. You can do this instead:

@for (var i = 0; i < Model.searchChannelCode.Length; i++)
{
    @Html.HiddenFor(m => m.searchChannelCode[i]);
}