Validation Summary for Collections - asp.net-mvc

Question

EDIT: upgraded this question to MVC 2.0
With asp.net MVC 2.0 is there an existing method of creating Validation Summary that makes sense for models containing collections? If not I can create my own validation summary
Example Model:
public class GroupDetailsViewModel
{
public string GroupName { get; set; }
public int NumberOfPeople { get; set; }
public List<Person> People{ get; set; }
}
public class Person
{
[Required(ErrorMessage = "Please enter your Email Address")]
[RegularExpression(#"^([a-zA-Z0-9_\-\.]+)#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$", ErrorMessage = "Please enter a valid Email Address")]
public string EmailAddress { get; set; }
[Required(ErrorMessage = "Please enter your Phone Number")]
public string Phone { get; set; }
[Required(ErrorMessage = "Please enter your First Name")]
public string FirstName { get; set; }
[Required(ErrorMessage = "Please enter your Last Name")]
public string LastName { get; set; }
}
The existing summary <%=Html.ValidationSummary %> if nothing is entered looks like this.
The following error(s) must be corrected before proceeding to the next step
* Please enter your Email Address
* Please enter your Phone Number
* Please enter your First Name
* Please enter your Last Name
* Please enter your Email Address
* Please enter your Phone Number
* Please enter your First Name
* Please enter your Last Name
The design calls for headings to be inserted like this:
The following error(s) must be corrected before proceeding to the next step
Person 1
* Please enter your Email Address
* Please enter your Phone Number
* Please enter your First Name
* Please enter your Last Name
Person 2
* Please enter your Email Address
* Please enter your Phone Number
* Please enter your First Name
* Please enter your Last Name
Answer Based on Pharcyde's answer.
public static MvcHtmlString NestedValidationSummary(this HtmlHelper helper)
{
if (helper.ViewData.ModelState.IsValid)
return MvcHtmlString.Empty;
// create datastructure to group error messages under a given key (blank key is for general errors)
var errors = new Dictionary<string,List<string>>();
foreach (KeyValuePair<string, ModelState> keyPair in helper.ViewData.ModelState)
{
foreach (ModelError error in keyPair.Value.Errors)
{
//determine the 'key' for the group in which this error belongs
var key = keyPair.Key.Split(']')[0];
if (key.Contains("People["))
key = "Person " + key.Split('[')[1];
else
key = string.Empty;
if(!errors.ContainsKey(key))
errors.Add(key,new List<string>());
//now add message using error.ErrorMessage property
errors[key].Add(error.ErrorMessage);
}
}
// generate the HTML
var ul = new TagBuilder("ul");
foreach (KeyValuePair<string, List<string>> errorPair in errors.OrderBy(p=>p.Key))
{
var li = new TagBuilder("li");
if(!string.IsNullOrEmpty(errorPair.Key))
li.InnerHtml += string.Format("<p class=\"no-bottom-margin\"><strong>{0}</strong></p>",errorPair.Key);
var innerUl = new TagBuilder("ul");
foreach (var message in errorPair.Value)
{
var innerLi = new TagBuilder("li");
innerLi.InnerHtml = message;
innerUl.InnerHtml += innerLi.ToString(TagRenderMode.Normal);
}
li.InnerHtml += innerUl.ToString(TagRenderMode.Normal);
ul.InnerHtml += li.ToString(TagRenderMode.Normal);
}
return MvcHtmlString.Create(ul.ToString(TagRenderMode.Normal));
}

Answer 1

You are going to have to extend the HtmlHelper methods and roll your own. Heres the bit of code that is important for your situation where you need a group by:
//HtmlHelper being extended
if(helper.ViewData.ModelState.IsValid)
{
foreach(KeyValuePair<string,ModelState> keyPair in helper.ViewData.ModelState)
{
//add division for group by here using keyPair.Key property (would be named "Person" in your case).
foreach(ModelError error in keyPair.Value.Errors)
{
//now add message using error.ErrorMessage property
}
}
}