In this article I will explain with an example, how to pass and show Exception (Error) message from Controller to View in ASP.Net MVC Razor.
The Exception (Error) message will be displayed from Controller to View using Html.ValidationSummary Html Helper function in ASP.Net MVC Razor.
 
 
Configuring Bundles and enabling Client Side Validation
Please refer the following article for complete information on how to configure Bundles and enable Client Side validation in ASP.Net MVC project.
Using Bundles (ScriptBundle) in ASP.Net MVC Razor
Note: By default the validation done using Data Annotation attributes is Server Side. And hence to make it work Client Side, the Client Side validation must be enabled.
 
 
Model
The following Model class consists of one property Age to which the following validation Data Annotation attributes have been applied.
The Required Data Annotation attribute has been specified with a property Error Message with a string value. As the name suggests, this string value will be displayed to the user when the respective validation fails.
public class PersonModel
{
    [Display(Name = "Age")]
    [Required(ErrorMessage = "Age is required.")]
    public string Age { get; set; }
}
 
 
Controller
The Controller consists of two Action methods.
Action method for handling GET operation
Inside this Action method, simply the View is returned.
 
Action method for handling POST operation
This action method handles the POST operation and when the form is submitted, the object of the PersonModel class is sent to this method.
The value of the Age is converted to Integer format in the Try block and in case any error occurs it is handled by the Catch block.
Inside the Catch block, the Exception details are extracted from the Exception class object to form an HTML string message and finally the HTML string message is passed as parameter to the ModelState.AddModelError function.
public class HomeController : Controller
{
    // GET: Home
    public ActionResult Index()
    {
        return View();
    }
 
    [HttpPost]
    public ActionResult Index(PersonModel person)
    {
        try
        {
            int age = int.Parse(person.Age);
        }
        catch (Exception ex)
        {
            string message = string.Format("<b>Message:</b> {0}<br /><br />", ex.Message);
            message += string.Format("<b>StackTrace:</b> {0}<br /><br />", ex.StackTrace.Replace(Environment.NewLine, string.Empty));
            message += string.Format("<b>Source:</b> {0}<br /><br />", ex.Source.Replace(Environment.NewLine, string.Empty));
            message += string.Format("<b>TargetSite:</b> {0}", ex.TargetSite.ToString().Replace(Environment.NewLine, string.Empty));
            ModelState.AddModelError(string.Empty, message);
        }
 
        return View();
    }
}
 
 
View
Inside the View, in the very first line the PersonModel class is declared as Model for the View.
The View consists of an HTML Form which has been created using the Html.BeginForm method with the following parameters.
ActionName–Name of the Action. In this case the name is Index.
ControllerName – Name of the Controller. In this case the name is Home.
FormMethod – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
Inside the View, the following six HTML Helper functions are used:-
1. Html.LabelFor – Displaying the Model property name.
2. Html.TextBoxFor – Creating a TextBox for the Model property.
3. Html.ValidationMessageFor – Displaying the Validation message for the property.
4. Html.Raw – Rendering HTML content in View.
5. HttpUtility.HtmlDecode – Decoding the HTML string.
6. Html.ValidationSummary – The ValidationSummary will be used for displaying the Exception Error message from the Controller. Since the Exception Error message is in HTML format, the output from the Html.ValidationSummary is decoded using HttpUtility.HtmlDecode method and then displayed using Html.Raw Helper method.
There is also Submit button which when clicked, the Form gets submitted.
The jQuery and the jQuery Validation script bundles are rendered at the end of the Model using the Scripts.Render function.
@model MobileNumber_Validation_MVC.Models.PersonModel
 
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width"/>
    <title>Index</title>
    <style type="text/css">
        body {
            font-family: Arial;
            font-size: 10pt;
        }
        .error {
            color: red;
        }
        .exception {
            color: brown;
        }
    </style>
</head>
<body>
    @using (Html.BeginForm("Index", "Home", FormMethod.Post))
    {
        <table>
            <tr>
                <td>@Html.LabelFor(m => m.Age)</td>
                <td>@Html.TextBoxFor(m => m.Age)</td>
                <td>@Html.ValidationMessageFor(m => m.Age, "",new { @class = "error" })</td>
            </tr>
            <tr>
                <td></td>
                <td><input type="submit" value="Submit"/></td>
                <td></td>
            </tr>
        </table>
        @Html.Raw(HttpUtility.HtmlDecode((Html.ValidationSummary(false, "", new { @class = "exception" })).ToHtmlString()))
    }
</body>
@Scripts.Render("~/bundles/jquery")
@Scripts.Render("~/bundles/jqueryval")
</html>
 
 
Screenshot
Pass (Show) Exception Error Message from Controller to View in ASP.Net MVC
 
 
Downloads
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