How to set the textbox border color red when validation fails

asp.net, asp.net-mvc-3-areas, asp.net-mvc-4, jquery

Solution

public static List<string> GetTextBoxColor(this ModelStateDictionary ModelState)
    {
        string textBoxColor = string.Empty;
        int count = 1;
        List<string> list = new List<string>();
        var errorKeys = (from item in ModelState
                         where item.Value.Errors.Any()
                         select item.Key.Substring(item.Key.LastIndexOf('.')).Trim('.')).ToList();
        foreach (var item in errorKeys)
        {
            textBoxColor += string.Format("{0}.{1}</br>", count, item);
            list.Add(item);
            count++;
        }
        return list;

    }

Problem

I have got a task to set red color border for text box when the validation fails in .net mvc 4. BExtensionMethods.cs ``` public static string GetTextBoxColor(this ModelStateDictionary ModelState) { string textBoxColor = string.Empty; int count = 1; var errorKeys = (from item in ModelState where item.Value.Errors.Any() select item.Key).ToList(); foreach (var item in errorKeys) { textBoxColor += string.Format("{0}.{1}</br>", count, item); count++; } return textBoxColor; } ``` Here the json object contains the values.How can I filter it?

Original source