CODEWITHSUNDEEP
c#asp.net-mvcasp.net-mvc-4profiling
uioporqwerty
uioporqwerty

Reputation: 317

Getting values for a Model property from a Web API call

Currently I'm populating dropdowns options using an API call. In my model I have something like this:

public List<SelectListItem> getOptions
        {
            get
            {
                var options = WebApiHelper.Download<IEnumerable<T>>(
                "Controller");
                var dropDownOptions = options.Select(x => new SelectListItem { Text = x.Name, Value = x.Id.Value }).ToList();
                return dropDownOptions;
            }
        }

And this is called in a couple of places in the .cshtml (e.g. see below):

 @Html.DropDownListFor(m => m.someProperty, Model.getOptions)

List<SelectListItem> GetDropdownOptions()
        {
            var currentDropdownItems = Model.getOptions;
            //some other code to modify dropdown options.
        }

Will the Web API only be hit once when I call Model.getOptions? Or will it be called every time since it is inside the get for that property? If it is the latter, what is a good work around for that issue?

Edit: thought about it a little more, would it be better to have these controller populate the values for that property? I have a feeling that an api call gets placed on every call to model.getoptions.

Upvotes: 2

Views: 1408

Answers (1)

user3559349
user3559349

Reputation:

You WebApiHelper.Download() will be called each time you access the property and, if you were editing a collection, your current implementation could seriously degrade performance.

While you could define a private field (say) private List<SelectListItem> _Options; and in the getter, check if its null and if so, populate it using your WebApiHelper.Download() method, and then return _Options; this is still not a preferred implementation since you cannot easily unit test your app.

private List<SelectListItem> _options;
public List<SelectListItem> getOptions
{
  get
  {
    if (_options == null)
    {
      _options = // call your service
    }
    return _options;
  }
}

Keep your view models as dumb as possible and make your property

public List<SelectListItem> Options { get; set; }

and in the controller, initialize your model and call WebApiHelper.Download() to populate the collection (and inject WebApiHelper into your controller)

Upvotes: 2

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