private static object BindChoices(ModelBindingContext bindingContext)
{
// By convention we append .Id in the html inputs to emphasize that we are referring to entities by their Id.
string valueKey = string.Format("{0}.Id", bindingContext.ModelName);
var provider = bindingContext.ValueProvider.GetValue(valueKey);
string attemptedValuesString = provider != null ?
provider.AttemptedValue :
null;
Type choicesType = bindingContext.ModelType.GetGenericArguments().FirstOrDefault();
if (choicesType == null)
{
return(null);
}
var choices = bindingContext.Model ??
Activator.CreateInstance(typeof(Choices <>).MakeGenericType(choicesType));
if (!string.IsNullOrEmpty(attemptedValuesString))
{
var viewModelsList = Activator.CreateInstance(typeof(List <>).MakeGenericType(choicesType)) as IList;
// When the HTTP params contain more than one key-value pair with the same key, they are joined with commas
var attemptedValues = attemptedValuesString.Split(',');
foreach (string attemptedValue in attemptedValues)
{
int id = default(int);
bool success = false;
try
{
id = int.Parse(attemptedValue);
success = true;
}
catch (FormatException ex)
{
bindingContext.ModelState.AddModelError(valueKey, ex);
}
if (success)
{
var viewModel = Activator.CreateInstance(choicesType) as IEntityViewModel;
viewModel.Id = id;
viewModelsList.Add(viewModel);
}
}
GenericHelpers.SetChoicesSelection(choicesType, choices, viewModelsList);
}
return(choices);
}