using a viewmodel to assign values from a soap web service to a dropdownlist - web-services

Question

I need some advice on getting values from a soap web service to display in a dropdownlist using a viewmodel, I currently receive the data for the various dropdownlists from a service class found in a service class library project (n-tier application).
The code for the dropdownlist service follows a similar format to the code below:
public IEnumerable<SelectListItem> getValuesAsSelectItems(string selected)
{
var items = new List<SelectListItem>();
items.Add(new SelectListItem { Text = "Please Select", Value = string.Empty, Selected = (selected == string.Empty) });
foreach (var value in this.getValues())
{
items.Add(new SelectListItem { Text = value.Value, Value = value.Value, Selected = (selected == value.Value) });
}
return new SelectList(items, "Value", "Text");
}
I need a way of passing the values from this service to the viewmodel I have then created 7 controllers for each of the dropdownlist which will all link to partial views that I can reuse throughout the application, dropdownlists include titles, countries, states and others.

Answer 1

An approach you could take is to extract the drop down list values into a viewmodel of their own. So:
Step 1: Create a view model (ItemsViewModel) that encapsulates the drop down list items:
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web;
using System.Web.Mvc;
namespace Models
{
public class DropDownListItem
{
public string Text { get; set; }
public string Value { get; set; }
}
public class ItemsViewModel
{
private readonly List<DropDownListItem> _items;
// The selected item:
public string SelectedItem { get; set; }
// The items:
public IEnumerable<SelectListItem> Items
{
get
{
var allItems = _items.Select(i => new SelectListItem
{
Value = i.Value,
Text = i.Text
});
return DefaultItem.Concat(allItems);
}
}
// Default item (i.e. the "select" text) if none selected
public IEnumerable<SelectListItem> DefaultItem
{
get
{
return Enumerable.Repeat(new SelectListItem
{
Value = "-1",
Text = "Select an item"
}, count: 1);
}
}
public ItemsViewModel()
{
}
// Constructor taking in items from service and selected item string:
public ItemsViewModel(List<DropDownListItem> items, string selected)
{
_items = items;
SelectedItem = selected;
}
}
}
Step 2: Create a partial view in the Views folder that binds to the ItemsViewModel:
#model Models.ItemsViewModel
#Html.DropDownListFor(m => m.SelectedItem, Model.Items)
Step 3: In the appropriate controller (e.g. HomeController), place the child action that pulls the data from the service, the view model and the partial view together:
[ChildActionOnly]
public ActionResult DropDownList(string type, string selected)
{
// If you need to call different services based on the type (e.g. Country), then pass through "type" and base the call on that
var items = new ItemsViewModel(
(from g in _service.getTitles() select new DropDownListItem { Text = g.Text, Value = g.Value }).ToList(),
selected);
return PartialView("DropDownPartial", items);
}
Step 4: Drop this line of code into the view where you need the drop down list:
#Html.Action("DropDownList", "Home", new { selected = "2", type = "country" })
Note that selected and type are to be determined whichever way you see fit and are optional.
Hopefully this gives you some inspiration.