ASP.Net MVC Dynamic DropDownList - how to create one

Question

I am using an Editor template - as I need to loop through my model, and display/edit many of the RatesList objects in my model.

This ensures the ID and Name are correct - so they bind back to my model on Post back to the controller.

However the drop down list, needs to be dynamic - so has to show from 0 to whatever my Model.TypeCount is.

Is there anyway of me using the @Html.DropDownListFor helper - so that the drop down list is named correctly? In my code below, it is just a select statement - as I don't know how to make the drop down list dynamic - but then the naming convention isn't used, and the drop down list is not binding back to my model. My Editor View is:

@model ebs.Models.RatesList
@{ Layout = null; }
<tr>
<td>
    @Html.TextBoxFor(modelItem => modelItem.TypeID)
</td>
<td>
    @{ var num = Model.TypeCount; }

    <select id="NumSelected" name="NumSelected">
        @for (var i = 0; i <= num; i++)
        {
            <option value="@i">@i</option>
        }
    </select>
</td>
</tr>

Thanks for any help,

Mark

Darin Dimitrov · Accepted Answer · 2014-02-16 16:19:19Z

6

@model ebs.Models.RatesList
@{ Layout = null; }
<tr>
    <td>
        @Html.TextBoxFor(modelItem => modelItem.TypeID)
    </td>
    <td>
        @Html.DropDownList(
            "NumSelected", 
            Enumerable
                .Range(0, Model.TypeCount)
                .Select(x => new SelectListItem 
                { 
                    Value = x.ToString(), 
                    Text = x.ToString() 
                })
        )
    </td>
</tr>

But obviously it would be much better to define this as part of your view model:

public class RatesList
{
    public int NumSelected { get; set; }
    public IEnumerable<SelectListItem> Values
    {
        get 
        {
            return Enumerable
                .Range(0, this.TypeCount)
                .Select(x => new SelectListItem 
                { 
                    Value = x.ToString(), 
                    Text = x.ToString() 
                })        
        }
    }

    ... some other properties
}

and then in your view you would simply bind the dropdown to the corresponding properties of your view model:

@model ebs.Models.RatesList
@{ Layout = null; }
<tr>
    <td>
        @Html.TextBoxFor(modelItem => modelItem.TypeID)
    </td>
    <td>
        @Html.DropDownListFor(modelType => modellType.NumSelected, Model.Values)
    </td>
</tr>

answered Feb 16, 2014 at 16:19

Darin Dimitrov

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1 Comment

Mark Over a year ago

Once again Darin - you've so eloquently coded a solution to a problem. Thanks a lot - I'll mark as the answer when stack overflow allows. Cheers, Mark

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