Question

So, I am trying to create a DropDownList that will edit the various member variables the DateTime class has (which I have an instance of in my model), such as Day, Month, and Year. However, when an item is selected in the DropDownList and the Save input button is clicked, the data does not save. All other edited pieces of data will be changed and saved, but the DateTime field will just not update. I’d rather not make a new model just for my Dates, but it can be done. I can create the SelectList, I do so in an HTML Helper, shown below:

namespace ErrorReport.Helpers
{
public class DateList
{
    public static IEnumerable<SelectListItem> DayList
    {
        get
        {
            var days = new List<SelectListItem>();
            for (int i = 1; i < 32; i++)
            {
                days.Add(new SelectListItem
                {
                    Value = i.ToString(),
                    Text = i.ToString()
                });
            }
            return days;
        }
    }

There’s obviously two more Lists that get made, one for Year and one for Month (I’m not bothering with hours, minutes, or seconds), didn’t show them since the code is identical. In my View, my editor code looks like the below, and the variable I want to change is CmpD (of DateTime class):

<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" 
        type="text/javascript"></script>

<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")"
        type="text/javascript"></script>

@using (Html.BeginForm())
{
@Html.ValidationSummary(true)
<fieldset>
    <legend>Edit Report: "@Model.Title"</legend>

    @Html.HiddenFor(model => model.ReportId)
    @Html.HiddenFor(model => model.SbmD)
    @Html.HiddenFor(model => model.UserName)
    @Html.HiddenFor(model => model.CmpD)

    ...irrelevant editor code...

    <div class="editor-label">
        @Html.LabelFor(model => model.CmpD, "Estimated Completion Date:")
    </div>

    <div class="editor-field">  

        @Html.DropDownListFor(model => model.CmpD.Month, DateList.MonthList)
        @Html.DropDownListFor(model => model.CmpD.Day, DateList.DayList)
        @Html.DropDownListFor(model => model.CmpD.Year, DateList.YearList)

        //@Html.ValidationMessageFor(model => model.CmpD.Month)
        //Above line was commented out
    </div>
    <p>
        <input type="submit" value="Save"/>
    </p>
</fieldset>
}

I did have validation in place for CmpD's member variables earlier (only the ones I wanted to change), commented them out because they kept throwing validation errors for every possible SelectList choice (marked in above code). I didn’t put arguments in the BeginForm function because they caused save problems with saving the other data. I also added the HiddenFor field for CmpD (which is my DateTime) to get everything to save properly, since without that line of code the return controller did not recognize the Model as valid and didn’t save it. I tried adding a HiddenFor field for every member variable in the DateTime class I am not using, and I still get Validation errors if I remove the HiddenFor(model => model.CmpD), even with other Hidden Fields present. I have also tried to make a list this way:

    public static IEnumerable<int> YearList
    {
        get
        {
            var years = new List<int>();
            for (int i = 0; i < 4; i++)
            {
                years.Add(i);
            }
            return years.AsEnumerable();
        }
    }

However, this prevents the Html.DropDownListFor function from working at all, it apparently has to use SelectList items. I have noticed that only strings can be SelectList items, and that the DateTime member variables are ints. Is that causing the problem? Because I don’t see where they are recasted to ints and cannot figure out how I would do that. Basically, how do I edit DateTime member variables in a DropDownList?

Also: Is this too much inline code? Thanks in advance!

Answer 1

The DateTime properties (Day, Month, etc.) are all read-only. Hence, it is not possible to set them on a DateTime instance.
You would need settable int properties in your model to be able to update the values from the drop-downs. Then you can construct a DateTime from those values later. I would probably create a separate model class just for this purpose and implement the date editor as separate editor template or partial view that handles all the details (to keep your code clean).