EditorFor IEnumerable<T> with TemplateName
There, now I only owe Darin 9999 beers.
public static MvcHtmlString EditorForMany<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, IEnumerable<TValue>>> expression, string templateName = null) where TModel : class
{
StringBuilder sb = new StringBuilder();
// Get the items from ViewData
var items = expression.Compile()(html.ViewData.Model);
var fieldName = ExpressionHelper.GetExpressionText(expression);
var htmlFieldPrefix = html.ViewContext.ViewData.TemplateInfo.HtmlFieldPrefix;
var fullHtmlFieldPrefix = String.IsNullOrEmpty(htmlFieldPrefix) ? fieldName : String.Format("{0}.{1}", htmlFieldPrefix, fieldName);
int index = 0;
foreach (TValue item in items)
{
// Much gratitude to Matt Hidinger for getting the singleItemExpression.
// Current html.DisplayFor() throws exception if the expression is anything that isn't a "MemberAccessExpression"
// So we have to trick it and place the item into a dummy wrapper and access the item through a Property
var dummy = new { Item = item };
// Get the actual item by accessing the "Item" property from our dummy class
var memberExpression = Expression.MakeMemberAccess(Expression.Constant(dummy), dummy.GetType().GetProperty("Item"));
// Create a lambda expression passing the MemberExpression to access the "Item" property and the expression params
var singleItemExpression = Expression.Lambda<Func<TModel, TValue>>(memberExpression,
expression.Parameters);
// Now when the form collection is submitted, the default model binder will be able to bind it exactly as it was.
var itemFieldName = String.Format("{0}[{1}]", fullHtmlFieldPrefix, index++);
string singleItemHtml = html.EditorFor(singleItemExpression, templateName, itemFieldName).ToString();
sb.AppendFormat(singleItemHtml);
}
return new MvcHtmlString(sb.ToString());
}
Is it any other, cleaner solution to do this?
The simple answer is no, it sucks badly, I completely agree with you, but that's how the designers of the framework decided to implement this feature.
So what I do is I stick to the conventions. Since I have specific view models for each views and partials it's not a big deal to have a corresponding editor template, named the same way as the type of the collection.