[html] How do I get the collection of Model State Errors in ASP.NET MVC?

How do I get the collection of errors in a view?

I don't want to use the Html Helper Validation Summary or Validation Message. Instead I want to check for errors and if any display them in specific format. Also on the input controls I want to check for a specific property error and add a class to the input.

P.S. I'm using the Spark View Engine but the idea should be the same.

So I figured I could do something like...

<if condition="${ModelState.Errors.Count > 0}">
  DispalyErrorSummary()
</if>

....and also...

<input type="text" value="${Model.Name}" 
       class="?{ModelState.Errors["Name"] != string.empty} error" />

....

Or something like that.

UPDATE

My final solution looked like this:

<input type="text" value="${ViewData.Model.Name}" 
       class="text error?{!ViewData.ModelState.IsValid && 
                           ViewData.ModelState["Name"].Errors.Count() > 0}" 
       id="Name" name="Name" />

This only adds the error css class if this property has an error.

This will give you one string with all the errors with comma separating

string validationErrors = string.Join(",",
                    ModelState.Values.Where(E => E.Errors.Count > 0)
                    .SelectMany(E => E.Errors)
                    .Select(E => E.ErrorMessage)
                    .ToArray());

Thanks Chad! To show all the errors associated with the key, here's what I came up with. For some reason the base Html.ValidationMessage helper only shows the first error associated with the key.

    <%= Html.ShowAllErrors(mykey) %>

HtmlHelper:

    public static String ShowAllErrors(this HtmlHelper helper, String key) {
        StringBuilder sb = new StringBuilder();
        if (helper.ViewData.ModelState[key] != null) {
            foreach (var e in helper.ViewData.ModelState[key].Errors) {
                TagBuilder div = new TagBuilder("div");
                div.MergeAttribute("class", "field-validation-error");
                div.SetInnerText(e.ErrorMessage);
                sb.Append(div.ToString());
            }
        }
        return sb.ToString();
    }

Got this from BrockAllen's answer that worked for me, it displays the keys that have errors:

    var errors =
    from item in ModelState
    where item.Value.Errors.Count > 0
    select item.Key;
    var keys = errors.ToArray();

Source: https://forums.asp.net/t/1805163.aspx?Get+the+Key+value+of+the+Model+error

If you don't know what property caused the error, you can, using reflection, loop over all properties:

public static String ShowAllErrors<T>(this HtmlHelper helper) {
    StringBuilder sb = new StringBuilder();
    Type myType = typeof(T);
    PropertyInfo[] propInfo = myType.GetProperties();

    foreach (PropertyInfo prop in propInfo) {
        foreach (var e in helper.ViewData.ModelState[prop.Name].Errors) {
            TagBuilder div = new TagBuilder("div");
            div.MergeAttribute("class", "field-validation-error");
            div.SetInnerText(e.ErrorMessage);
            sb.Append(div.ToString());
        }
    }
    return sb.ToString();
}

Where T is the type of your "ViewModel".

Here is the VB.

Dim validationErrors As String = String.Join(",", ModelState.Values.Where(Function(E) E.Errors.Count > 0).SelectMany(Function(E) E.Errors).[Select](Function(E) E.ErrorMessage).ToArray())

Putting together several answers from above, this is what I ended up using:

var validationErrors = ModelState.Values.Where(E => E.Errors.Count > 0)
    .SelectMany(E => E.Errors)
    .Select(E => E.ErrorMessage)
    .ToList();

validationErrors ends up being a List<string> that contains each error message. From there, it's easy to do what you want with that list.

Condensed version of @ChrisMcKenzie's answer:

var modelStateErrors = this.ModelState.Values.SelectMany(m => m.Errors);

To just get the errors from the ModelState, use this Linq:

var modelStateErrors = this.ModelState.Keys.SelectMany(key => this.ModelState[key].Errors);