ASP.NET MVC (razor) Listbox multiselect values to string

Question

I have two multi-select list boxes; one with months and one with years such as the following:

@Html.ListBoxFor(m => m.IncludeGuestsArrivedInTimeframeMonths, Model.TimeframeMonths)
@Html.ListBoxFor(m => m.IncludeGuestsArrivedInTimeframeYears, Model.TimeframeYears)

I'm saving the both values to the database as a comma separated list (string/nvarchar). The values are being like this: Months: 1,3,7; Years: 2002,2005

For some reason when I pull the values back out to the form, the months are pre-selecting in the listbox fine, but the years are not.

Any ideas?

EDIT - Additional code samples:

Controller - Manage

public ActionResult Manage(Guid id)
    {
        var list = _listService.GetList(id);

        var model = LoadModelFromObject(list);
        model.TimeframeMonths = GenerateMonthDropdown();
        model.TimeframeYears = GenerateYearDropdown(model.IncludeGuestsArrivedInTimeframeYears.Split(','));
        model.DaysOfWeek = GenerateDaysOfWeekDropdown();

        return View(model);
    }

Controller - 'Helper'

private IList<SelectListItem> GenerateYearDropdown(string[] selected)
    {
        var list = new List<SelectListItem>();

        var startYear = DateTime.Now.Year - 10;

        for (int idx = startYear; idx < startYear + 11; idx++)
        {
            list.Add(new SelectListItem
                         {
                             Value = idx.ToString(),
                             Text = idx.ToString(),
                             Selected = selected != null && selected.Contains(idx.ToString())
                         });
        }

        return list;
    }

View

@Html.CheckBoxFor(m => m.IncludeGuestsArrivedInTimeframe)
@Html.LabelFor(m => m.IncludeGuestsArrivedInTimeframe)
@Html.ListBoxFor(m => m.IncludeGuestsArrivedInTimeframeMonths, Model.TimeframeMonths)
@*@Html.ListBoxFor(m => m.IncludeGuestsArrivedInTimeframeYears, Model.TimeframeYears)*@
@Html.ListBox("IncludeGuestsArrivedInTimeframeYears", Model.TimeframeYears)

What does Model.TimeframeYears return? I mean the values. It must return type of IEnumerable<SelectListItem> but I cannot see what values it has. — tugberk
– tugberk, Commented Jan 4, 2012 at 15:28
@tugberk The Model.TimeframeYears has the IList<SelectListItem> and the Value and Text of each SelectListItem are the year (2002) — Matt Millican
– Matt Millican, Commented Jan 4, 2012 at 15:46
Could you provide sample values illustrating the problem of the IncludeGuestsArrivedInTimeframeYears and TimeframeYears properties? — Darin Dimitrov
– Darin Dimitrov, Commented Jan 4, 2012 at 17:45
See my DDL tutorials asp.net/mvc/tutorials/javascript/… and blogs.msdn.com/b/rickandy/archive/2012/01/09/… — RickAndMSFT
– RickAndMSFT, Commented Feb 14, 2012 at 19:54

tugberk · Accepted Answer · 2012-01-04 18:34:46Z

4

You need to set Selected property of SelectItemList class to true for the options which you want to be pre-selected.

Example:

@{
    var foo = new List<SelectListItem> { 
        new SelectListItem { Text = "Foo 1", Value = "1", Selected = true },
        new SelectListItem { Text = "Foo 2", Value = "2" },
        new SelectListItem { Text = "Foo 3", Value = "3", Selected = true }
    };
}

@Html.ListBox("foo", foo)

In this case, Foo 1 and Foo 3 should appear as pre-selected. The above code generates the below html markup:

<select id="foo" multiple="multiple" name="foo">
    <option selected="selected" value="1">Foo 1</option>
    <option value="2">Foo 2</option>
    <option selected="selected" value="3">Foo 3</option>
</select>

Edit:

First of all, replace this code:

list.Add(new SelectListItem {
     Value = idx.ToString(),
     Text = idx.ToString(),
     Selected = selected != null && selected.Contains(idx.ToString())
});

with this code:

list.Add(new SelectListItem {
     Value = idx.ToString(),
     Text = idx.ToString(),
     Selected = true
});

Then run the app. If all the options are pre-selected, then I bet that this selected != null && selected.Contains(idx.ToString()) does not satisfy the condition.

edited Jan 4, 2012 at 18:34

answered Jan 4, 2012 at 16:01

tugberk

58.7k71 gold badges252 silver badges342 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Matt Millican Over a year ago

Okay, I changed it up a little bit. I have a method called GenerateYearDropdown which I modified to take an array of strings, which I pass in. The array is being passed in correctly, and setting the selected value of each list item, but it's not displaying those selections on the form.

tugberk Over a year ago

@mmillican did you try out the above code? It works on my machine and should work on yours, too. The problem is with your code, post it as well.

Matt Millican Over a year ago

I updated it and set Selected = true for all the entries and it's still not selecting them. Any other ideas? Sorry for the hassle!

Matt Millican Over a year ago

Looks like they're not being selected. I was hoping to be able to send it to the view from the controller but maybe I won't be able to do that. Thx!

olyv · Accepted Answer · 2014-07-01 16:14:57Z

1

Another way of doing it

@Html.ListBox("categoryId", new MultiSelectList(ViewData["categories"] as System.Collections.IEnumerable, "Id", "CategoryName", Model.tIdx_ProductCategories.Select(x => x.CategoryId).AsEnumerable()))

Explanation:

categoryId - would be name of control, when rendered as html
ViewData["categories"] - is list of categories with Id and CategoryName properties
Model.tIdx_ProductCategories carries the list of category ids to be selected in list box.

edited Jul 1, 2014 at 16:14

olyv

3,8275 gold badges39 silver badges70 bronze badges

answered Jul 1, 2014 at 15:51

Navpreet Singh

111 bronze badge

Comments

Community · Accepted Answer · 2017-05-23 11:48:33Z

0

As it seems (e.g. here Preselect Items in Multiselect-Listbox (MVC3 Razor)) the Razor engine happily ignores the Selected property and compares the list from the model and the supplied option list by calling ToString() on the objects from the model and using string comparison to select.

What I cannot explain to myself is why this behavior is used with Html.ListBox(), which does not use any model and expects a collection of SelectListItem.

Think it's a bug, but it does not seem to have been addressed recently.

edited May 23, 2017 at 11:48

CommunityBot

11 silver badge

answered Dec 23, 2013 at 14:04

Alex Mazzariol

2,5761 gold badge22 silver badges22 bronze badges

Collectives™ on Stack Overflow

ASP.NET MVC (razor) Listbox multiselect values to string

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related