mvc: How do I add a initial Item to a DropDownList with Key of 0 and Description of 'Show All'

Question

Here is an extract of my FormViewModel :

    public SummaryFormViewModel(IEnumerable<Site> sites, IEnumerable<Landowner> landowners)
    {

        var sitesValues = sites
            .OrderBy(s => s.SiteDescription)
            .Select(s => new KeyValuePair<int, string>(s.SiteId, s.SiteDescription));
        this.Sites = new SelectList(sitesValues, "Key", "Value");

I'd like to insert (as the first item) a value that will automatically be the default. It is to have a key of 0 and a description of 'Show All'

Basically i'm offering combo boxes to the user to allow them to filter results.

I'm needing a neat way to add this initial row to the SelectList

Can anyone Advise me please, thanks in Advance

J

Answer 1

You can use .ToList() then .Insert() to add in a new value.

Example:

    var sitesValues = sites
        .OrderBy(s => s.SiteDescription)
        .Select(s => new KeyValuePair<int, string>(s.SiteId, s.SiteDescription))
        .ToList();
    sitesValues.Insert(0, new KeyValuePair<int, string>(0, "Show All"));

    this.Sites = new SelectList(sitesValues, "Key", "Value");

Answer 2

One of the overloads of the HTML.Dropdown method accepts a label for the first item. Something like:

Html.Dropdown("MyDropdown", Model.Sites, "Show All")

See http://msdn.microsoft.com/en-us/library/dd492883.aspx