Disable enable dropdownlistfor based on model property in mvc

Question

I am trying to disable or enable a dropdownlistfor in my mvc application based on model property:-

what I am doing is :-

@Html.DropDownListFor(m => m.         


        

Answer 1

It is not possible to include the condition (if/ternary statement(s)) inside the call to the DropDownListFor helper method because you cannot pass a line of c# code (with your if condition) where it expects an object for html attributes. Also all of the below markups will render a disabled SELECT.

You can simply check the value of your Model property with an if condition and conditionally render the disabled version.

@if (!Model.IsReadOnly)
{
    @Html.DropDownListFor(s => s.ParentOrganisationID, 
                               new SelectList(Model.ParentOrganisations, "ID", "Name"))
}
else
{
    @Html.DropDownListFor(s => s.ParentOrganisationID, 
       new SelectList(Model.ParentOrganisations, "ID", "Name"),new {disabled="disabled"})
}

You may consider creating a custom html helper method which takes care of the if condition checking.

public static class DropDownHelper
{
    public static MvcHtmlString MyDropDownListFor
                 (this HtmlHelper htmlHelper, 
                  Expression> expression,
                  IEnumerable selectItems,
                  object htmlAttributes,
                  bool isDisabled = false)
    {
        ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression,
                                                                    htmlHelper.ViewData);

        IEnumerable items =
            selectItems.Select(value => new SelectListItem
            {
                Text = value.Text,
                Value = value.Value,
                Selected = value.Equals(metadata.Model)
            });
        var attributes = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
        if (isDisabled && !attributes.ContainsKey("disabled"))
        {
             attributes.Add("disabled", "disabled");
        }
        return htmlHelper.DropDownListFor(expression,items, attributes);
    }
}

Now in your razor view,call this helper

@Html.MyDropDownListFor(s=>s.ParentOrganisationID,
               new SelectList(Model.ParentOrganisations, "ID", "Name")
                                           ,new { @class="myClass"},Model.IsReadOnly)