The accepted answer is great if the type is an integer, but a lot of ids wind up being typed as a string to prevent losing leading zeros.  You can format a string by breaking it up into pieces with `Substring` and make it reusable by sticking it in a DisplayTemplate.

Inside `/Shared/DisplayTemplates/`, add a template named `Phone.vbhtml`:



    @ModelType String
    @If Not IsNothing(Model) AndAlso Model.Length = 10 Then
        @<span>@String.Format("({0}) {1}-{2}",
                  Model.Substring(0, 3),
                  Model.Substring(3, 3),
                  Model.Substring(6, 4))</span>
    Else
        @Model
    End If

You can invoke this in a couple ways:

1. Just annotate the property on your model with a data type of the same name:

    
    
        <DataType("Phone")> _
        Public Property Phone As String

   And then call using a simple `DisplayFor`:

    
    
         @Html.DisplayFor(Function(model) model.Phone)

2. Alternatively, you can specify the DisplayTemplate you'd like to use by name:

    
    
         @Html.DisplayFor(Function(model) model.VimsOrg.Phone, "Phone")

Is there a way I can use the `DisplayFormat` attribute on a view model property to apply a `DataFormatString` format for a social security number or a phone number?  I know I could do this with javascript, but would prefer to have the model handle it, if possible.

    [DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "???????")]
    public string Ssn { get; set; }



DisplayFormat.DataFormatString for a phone number or social security number

Here's [Maxim Gershkovich's solution][1] spelled out a little more:



    jQuery.validator.methods.date = function (value, element) {
        if (value) {
            try {
                $.datepicker.parseDate('dd/mm/yy', value);
            } catch (ex) {
                return false;
            }
        }
        return true;
    };


**Notes**:

* This depends on the [jQuery datepicker][2] method that comes with jQuery UI
* This is actually more robust that the native date validation that comes with jQueryValidate.   

  According to the docs on [date validation][3]:
  
  > Returns true if the value is a valid date. Uses JavaScript's built-in Date to test if the date is valid, and therefore **does no sanity checks**. Only the format must be valid, not the actual date, eg 30/30/2008 is a valid date.

  Whereas [`parseDate`][4] will check that the date is valid and actually exists.

[1]: https://stackoverflow.com/questions/15706455/1366033#comment39467632_15707341
[2]: http://jqueryui.com/datepicker/
[3]: http://jqueryvalidation.org/date-method/
[4]: http://api.jqueryui.com/datepicker/#utility-parseDate

I'm doing a simple MVC4 Internet application, which allows to add some items to the categories.

Here is what i've done so far.

I've a datepicker in mvc view. The script for the datepicker is like this.

    <script src="@Url.Content("~/Scripts/jquery-1.7.1.min.js")" type="text/javascript"></script>
    <script src="@Url.Content("~/Scripts/jquery-ui-1.8.20.min.js")" type="text/javascript"></script>
    @Scripts.Render("~/bundles/jqueryval")
    <script type="text/javascript">
        $(function () {
            $('#dtItemDueDate').datepicker({
                dateFormat: 'dd/mm/yy',
                minDate: 0
            });
        });
    </script>

My model property :

            [DisplayName("Item DueDate")]
            [Required]
            [DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}",ApplyFormatInEditMode = true)]
            [DataType(DataType.DateTime)]
            public DateTime? dtItemDueDate { get; set; }
            public char charCompleted { get; set; }

and in my view i've done this:

    @Html.TextBoxFor(m => m.dtItemDueDate)
    @Html.ValidationMessageFor(m => m.dtItemDueDate)

The error is like this:

    The field Item DueDate must be a date.

The strange this is that it does work in IE and mozilla, but doesnot work in Chrome.

I found many posts on SO, but none of them help

Any ideas/suggestions ?

The field date must be a date in mvc in chrome

You can also set the property type to [`Nullable<T>`][1], and then just manually enforce any required validation you might need to do before working with the database.



    public int? Id {get;set;}

**Further Reading**:

* [Unrequired property keeps getting data-val-required attribute][2]
* [ASP.NET MVC optional field being treated as required][3]
* ["The Id field is required" validation message on Create][4]



[1]: https://msdn.microsoft.com/en-us/library/b3h38hb0.aspx
[2]: https://stackoverflow.com/q/4700172/1366033
[3]: https://stackoverflow.com/q/13293207/1366033
[4]: https://stackoverflow.com/q/2142990/1366033

 I have a Model Like this

    public int Id {get;set;}

    [Required]
    public string FirstName{get; set}
    [Required]
    public string LastName{get; set}

The Id is auto generate in DB. when I want call Create action The ModelState says that "The Id field is required"!!!! I Found [this][1] for my problem but it not clean solution.
Is there an other way to solve this?

Is there a way that I change Mvc ModelBinder behavior for value types?


  [1]: https://stackoverflow.com/questions/2142990/asp-mvc-the-id-field-is-required-validation-message-on-create-id-not-set-to

Why MVC Model Binder set required for int, long values?

Here's another approach from [How to create custom validation attribute for MVC][1], which is adapted from this article on [ASP.NET MVC Custom Validation][2]:

    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false)]
    public class AlphaNumericAttribute: RegularExpressionAttribute
    {
        private const string pattern = "^[-A-Za-z0-9]+$";
    
        public AlphaNumericAttribute() : base(pattern)
        {
            // necessary to enable client side validation
            DataAnnotationsModelValidatorProvider.RegisterAdapter(
                typeof(AlphaNumericAttribute), 
                typeof(RegularExpressionAttributeAdapter));
        }
    }

By using [`RegisterAdapter`][3], you can leverage the integrations that already exist for regular expressions for your own inherited type.

[1]: https://stackoverflow.com/a/5954452/1366033
[2]: http://haacked.com/archive/2009/11/19/aspnetmvc2-custom-validation.aspx/
[3]: https://msdn.microsoft.com/en-us/library/system.web.mvc.dataannotationsmodelvalidatorprovider.registeradapter(v=vs.118).aspx

I have created the following custom RegularExpressionAttribute

    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false)]
    public class AlphaNumericAttribute: RegularExpressionAttribute, IClientValidatable
    {
        public AlphaNumericAttribute()
          : base("^[-A-Za-z0-9]+$")
        {
        }

       public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
       {
          yield return new ModelClientValidationRule { ErrorMessage =  FormatErrorMessage(metadata.GetDisplayName()), ValidationType = "alphanumeric" };
       }
    }

The field in the ViewModel is decorated with my AlphaNumeric attribute:

    [AlphaNumeric(ErrorMessageResourceType = typeof(Resources), ErrorMessageResourceName = Resources.DriverLicenseNumber_RegexError_)]
    public string DriverLicenseNumber { get; set; }

The field is built in the view:

    @using (Html.BeginForm("Index", "Application", FormMethod.Post, new { id = "applicationDataForm", autocomplete = "off" }))
    {
        @Html.LabelFor(m => m.DriverLicenseNumber)
        @Html.ValidationMessageFor(m => m.DriverLicenseNumber)
        @Html.TextBoxFor(m => m.DriverLicenseNumber)
    }

This should yield the proper *"data-"* validation attributes on my html input tag.  However, the rendered tag looks like this:

    <input data-val="true" data-val-alphanumeric="Please enter a valid driver's license number." id="DriverLicenseNumber" name="DriverLicenseNumber" type="text" value="" maxlength="20" class="valid">

Conspicuously absent are the *data-val-regex* and *data-val-regex-pattern* attributes that are supposed be rendered.  

I have built other validators with the exact same structure, and they work correctly, like this SSN validation which handles masked spaces for a masked input using jquery masking:

    public class SsnAttribute : RegularExpressionAttribute, IClientValidatable
    {
      public SsnAttribute()
      : base("^([0-9]{3}–[0-9]{2}–[0-9]{4})|([ ]{3}–[ ]{2}–[ ]{4})|([0-9]{9,9})$")
    {
    }

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
      yield return new ModelClientValidationRule { ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()), ValidationType = "ssn" };
    }
  }

With the accompanying application on the ViewModel:

    [Ssn(ErrorMessageResourceType = typeof(Resources), ErrorMessageResourceName = Resources.SocialSecurity_RegexError_)]
    public new string SocialSecurityNumber { get; set; }

The field is built in the view:
    
    @using (Html.BeginForm("Index", "Application", FormMethod.Post, new { id = "applicationDataForm", autocomplete = "off" }))
    {
        @Html.LabelFor(m => m.SocialSecurityNumber)
        @Html.ValidationMessageFor(m => m.SocialSecurityNumber)
        @Html.TextBoxFor(m => m.SocialSecurityNumber)
    }

This validation attribute correctly renders the data-val-regex and data-val-regex-pattern attributes:

    <input class="SSNMask valid" data-val="true" data-val-regex="Please enter a valid social security number." data-val-regex-pattern="^([0-9]{3}–[0-9]{2}–[0-9]{4})|([ ]{3}–[ ]{2}–[ ]{4})|([0-9]{9,9})$" id="SocialSecurityNumber" name="SocialSecurityNumber" type="text" value="" maxlength="22">

<br/><br/>
I cannot figure out what I am missing with the AlphaNumeric attribute that it does not render the appropriate html attributes.

Custom RegularExpressionAttribute missing data-val-regex-pattern for client-side validation

That's because `OnSuccess` vs `OnFailure` aren't hooked up to `ModeState.IsValid` in any way.

Per the [`AjaxOptions` docs][1]:

> [`OnSuccess`][2]: This function is called if the response status **is** in the 200 range.  
> [`OnFailure`][3]: This function is called if the response status **is not** in the 200 range.

In other words, you have to manually specify that there was a failure when returning your ActionResult by changing the `Response.StatusCode` and then returning whatever values you're expecting in your `OnFailure` js method.

    [HttpPost]
    public ActionResult Search(Person model) 
    {
      if (ModelState.IsValid) {
        // if valid, return a HTML view inserted by AJAX helper
        var results = PersonRepository.Get(model)
        return PartialView("Resulsts", vm);
        
      } else {
      	// if invalid, return a JSON object and handle with OnFailure method
        Response.StatusCode = (int)HttpStatusCode.BadRequest;
        return Json(new { errors = ModelState.Values.SelectMany(v => v.Errors) });
    
      }
    }


**Further Reading**: 

* [MVC 4 Ajax.BeginForm and ModelState.AddModelError][4]
* [ASP.NET MVC “Ajax.BeginForm” executes OnSuccess even though model is not valid][5]


[1]: https://msdn.microsoft.com/en-us/library/system.web.mvc.ajax.ajaxoptions.aspx
[2]: https://msdn.microsoft.com/en-us/library/system.web.mvc.ajax.ajaxoptions.onsuccess.aspx
[3]: https://msdn.microsoft.com/en-us/library/system.web.mvc.ajax.ajaxoptions.onfailure.aspx
[4]: https://stackoverflow.com/q/21311026/1366033
[5]: https://stackoverflow.com/q/7328977/1366033

This is a well-worn topic apparently but I've not been able to come up with a solution perusing previous posts. Hoping someone can tell me the "right way" to do this, since I need to do a lot of it. 

Main issue: When Ajax.Beginform post ModelState is invalid, it still triggers OnSuccess method. I know this is correct behavior, but my OnSuccess method does things that only make sense when (go figure) post is "successful." 

How best to manage redisplaying form with validation errors in this case? How do I return a success=false from my controller along with the view to be redisplayed? 

It's not specifically relevant to the question, but fyi what I'm doing here is somewhat analagous to trying to display a form in a Bootstrap Modal, which I gave up on. 

1) calling controller via ajax to load form in div. 

    $(function addpaneevent() {
        $('.addpane').on("click", function () {
            var url = '/QuizPane/QuickPane?quizId=' + $(this).data("quizid");
            $.ajax({
                url: url,
                type: 'GET',
                contentType: 'application/json',
                success: function (result) {
                    $('#overlay').html(result);
                },
                error: function (result) {
                    console.log("bummer",result);
                }
            });
        });
    });

2) return partial view containing form

    public ActionResult QuickPane(int quizId)
    {
        var model = *querytogetmodel*
        return PartialView("QuickPane",model);
    }


    @using (Ajax.BeginForm("QuickPane", "QuizPane", FormMethod.Post,
        new AjaxOptions
        {
                                InsertionMode = InsertionMode.Replace,
                                HttpMethod = "POST",
                                OnSuccess = "updatePaneList(data)",
                                OnFailure = "massivefail(data)",
        }))
    {
       @Html.ValidationSummary(true)
    
        <fieldset>
            @Html.HiddenFor(model => model.QuizID)
            <div class="editor-label">
                @Html.LabelFor(model => model.Title)
            </div>
            <div class="editor-field">
                @Html.TextBoxFor(model => model.Title, new { @autofocus = "autofocus" })
                @Html.ValidationMessageFor(model => model.Title)
            </div>
            ...more of the same
            <input type="submit" value="Create" class="btn btn-primary"/>
        </fieldset>
    }

3) On submit call post

    [HttpPost]
    public ActionResult QuickPane(QuizPane quizpane)
    {
        if (ModelState.IsValid)
        {
            db.QuizPanes.Add(quizpane);
            db.SaveChanges();
             return PartialView("_quizpanelist", quizpane);
        }
        return View(quizpane); //tried a few different things here
     }

4) On success I'm adding the new record to a table and removing the div containing the input form. 

    function updatePaneList(data) {
        $("#overlay").remove();
        var rowcount = $(".expanded #panetable tr:last").count;
        $('.expanded #panetable  tbody:last').append(data);        
    };





Ajax.Beginform post validation when Model.State invalid triggers OnSuccess function

Inlining Stephen Muecke's answer to [MVC5 Razor html.dropdownlistfor set selected when value is in array][1]

>Unfortunately `@Html.DropDownListFor()` behaves a little differently than other helpers when rendering controls in a loop. This has been previously reported as an issue on CodePlex (not sure if its a bug or just a limitation)

>The are 2 options to solve this to ensure the correct option is selected based on the model property

>---

>### **Option 1**  - Use an `EditorTemplate`

>Create a custom `EditorTemplate` for the type in the collection. Create a partial in `/Views/Shared/EditorTemplates/AggregationLevelConfiguration.cshtml` (note the name must match the name of the type


> 
    
>     @model yourAssembly.AggregationLevelConfiguration
    @Html.DropDownListFor(m => m.HelperCodeType, (SelectList)ViewData["CodeTypeItems"])
    .... // other properties of AggregationLevelConfiguration

> and then in the main view, pass the `SelectList` to the `EditorTemplate` as `additionalViewData`

> 

>     @using (Html.BeginForm())
    {
      ...
      @Html.EditorFor(m => m.Configurations , new { CodeTypeItems = Model.CodeTypeItems })
      ...

>---

>### **Option 2** - Generate a new `SelectList` in each iteration and set the `selectedValue`

>In this option your property `CodeTypeItems` should to be `IEnumerable<GenericIdNameType>`, not a `SelectList` (or just make `codeTypes` a public property). Then in the main view

> 

>     @Html.DropDownListFor(m => m.Configurations[0].HelperCodeType, new SelectList(Model.CodeTypeItems, "Id", "Name", Model.Configurations[0].HelperCodeType)

>**Side note**: there is no need to use `new { id = "Configurations[0].HelperCodeType"` - the `DropDownListFor()` method already generated that `id` attribute


Note: Also double check that you don't have other non-list related binding issues as described in these questions:

* [Html.DropdownListFor selected value not being set][2]
* [DropDownListFor Not Selecting Value][3]

[1]: https://stackoverflow.com/a/37411482/1366033
[2]: https://stackoverflow.com/q/19476530/1366033
[3]: https://stackoverflow.com/q/2278056/1366033

I have problems to set the default selected value of a DropDownList with DropDownListFor in ASP MVC 4.

When the property which I want to preselect is in a list it's never selected by default as expected.

Here is my code reduced to the important stuff:

Models:

    public class Renter
    {
	    ...
	    public virtual List<RentLine> RentLines { get; set; }
	    ...
	
        public Renter()
	    {
		    ...
            RentLines = new List<RentLine>();
		    ...
        }
    }
    
    public class RentLine
    {
        ...
        public Guid RenterId { get; set; }
        public virtual Renter Renter { get; set; }	
        public Guid GarageId { get; set; }
        public virtual Garage Garage { get; set; }
        ...
        
        public RentLine()
        {
            //
            // Testcase for default value in dropdownlist
            //
            GarageId = new Guid("e926dcac-05ac-4fc1-92a2-014345e6e11c");
        }
    }

Controller:

    public ActionResult Hinzufuegen()
    {
        var model = new AddRenterViewModel();
        return View(model);
    }

ViewModel:

	public class AddRenterViewModel
	{
		public Renter Renter { get; set; }
		
		public List<SelectListItem> RentableGarageItems { get; set; }
		
		...
		
		public AddRenterViewModel()
		{
			Renter = new Renter();
			Renter.RentLines.Add(new RentLine());
			
			RentableGarageItems = new List<SelectListItem>();
			foreach (var garage in Singleton.Instance.Entities.GetRentableGarages().OrderBy(g => g.No))
			{
				RentableGarageItems.Add(new SelectListItem{Text = garage.No.ToString(), Value = garage.Id.ToString()});
			}
		}	
	}

View:

	@model Grossgaragenverwaltung.ViewModels.AddRenterViewModel
	...
	Garage Nr. @Html.DropDownListFor(m => m.Renter.RentLines[0].GarageId, Model.RentableGarageItems) @* No selected value *@
			   @Html.TextBoxFor(m => m.Renter.RentLines[0].GarageId) @* Shows the id 'e926dcac-05ac-4fc1-92a2-014345e6e11c' as set in the constructor *@
	...

Here is the result, no selected value:

	Garage Nr.
	<select id="Renter_RentLines_0__GarageId" name="Renter.RentLines[0].GarageId" data-val-required="Das Feld "GarageId" ist erforderlich." data-val="true">
	<option value="225a761d-7d12-4e02-9d72-d54fb6934f05">1</option>
	<option value="d28fb4fb-d65b-4674-90d6-a4ab9636be80">2</option>
	<option value="e06b520b-e876-4870-b321-dc65f77967a7">3</option>
	<option value="56832d98-aa5a-4e1a-af44-2d7e00f2bb3a">4</option>
	<option value="551f1fa9-13a5-40ce-b795-50063e605027">5</option>
	<option value="bace4b40-92ab-4757-9716-2a2878c2c9e8">6</option>
	<option value="f9baf45b-96bf-463e-a234-a1522bfc9b9b">7</option>
	<option value="91d1d866-6346-4ab0-b2aa-35b56eeaf2b0">8</option>
	<option value="62eb3727-eab2-4180-90cd-7dc59119f44e">9</option>
	<option value="59768097-c772-4421-b907-a24397a106f5">10</option>
	<option value="270acf6b-e4e3-41c3-86dd-4381a313848a">11</option>
	<option value="923269cd-1ead-4346-90ce-6344acda5b1b">12</option>
	<option value="981ee61e-408b-4b08-a7d3-26c909f04a9d">13</option>
	<option value="f1c5043c-fe41-4a8e-8c58-e88363885de4">14</option>
	<option value="e926dcac-05ac-4fc1-92a2-014345e6e11c">15</option>
	<option value="5577dc00-7cfa-4bcd-99ad-3f356e4325ae">16</option>
	</select>
	<input id="Renter_RentLines_0__GarageId" type="text" value="e926dcac-05ac-4fc1-92a2-014345e6e11c" name="Renter.RentLines[0].GarageId">

How can i get this work?

UPDATE:
Here is a working example where everything works like expected, the problem occurs only in the case you see above:


	public class Renter
	{
		...
		public Salutation Salutation { get; set; }
		...

		public Renter()
		{
			...
			Salutation = Salutation.Male;
			...
		}
	}

	public ActionResult Hinzufuegen()
	{
		var model = new AddRenterViewModel();
		return View(model);
	}

	public class AddRenterViewModel
	{
		public Renter Renter { get; set; }

		public List&lt;SelectListItem&gt; SalutationItems { get; set; }

		...

		public AddRenterViewModel()
		{
			Renter = new Renter();
			Renter.RentLines.Add(new RentLine());

			SalutationItems = new List&lt;SelectListItem&gt;();
			foreach (Salutation salutation in Enum.GetValues(typeof(Salutation)))
			{
			   SalutationItems.Add(new SelectListItem { Text = NameEnum.GetName(salutation), Value = salutation.ToString() });
			}
		}   
	}

	@Html.DropDownListFor(m =&gt; m.Renter.Salutation, Model.SalutationItems)

	&lt;select id="Renter_Salutation" name="Renter.Salutation" data-val-required="Das Feld "Salutation" ist erforderlich." data-val="true"&gt;
	&lt;option value="Company"&gt;Firma&lt;/option&gt;
	&lt;option value="Male" selected="selected"&gt;Männlich&lt;/option&gt;
	&lt;option value="Female"&gt;Weiblich&lt;/option&gt;
	&lt;/select&gt;


DropDownListFor selected value does not work with property in list

Just to clarify the solution for other people hitting this question. The ajax helper fires `OnSuccess` vs `OnFailure` based on the returned HTTP Code per the [`AjaxOptions` docs][1]:

> [`OnSuccess`][2]: This function is called if the response status **is** in the 200 range.  
> [`OnFailure`][3]: This function is called if the response status **is not** in the 200 range.

In other words, you have to manually specify that there was a failure when returning your ActionResult by changing the `Response.StatusCode` and then returning whatever values you're expecting in your `OnFailure` js method.  You can drive that based on any business logic you want (i.e. `catch Exception ex)` or `!ModelState.IsValid` ...)

    [HttpPost]
    public ActionResult Search(Person model) 
    {
      if (ModelState.IsValid) {
        // if valid, return a HTML view inserted by AJAX helper
        var results = PersonRepository.Get(model)
        return PartialView("Resulsts", vm);
        
      } else {
      	// if invalid, return a JSON object and handle with OnFailure method
        Response.StatusCode = (int)HttpStatusCode.BadRequest;
        return Json(new { errors = ModelState.Values.SelectMany(v => v.Errors) });
    
      }
    }


**Further Reading**: 

* [MVC 4 Ajax.BeginForm and ModelState.AddModelError][4]
* [ASP.NET MVC “Ajax.BeginForm” executes OnSuccess even though model is not valid][5]


[1]: https://msdn.microsoft.com/en-us/library/system.web.mvc.ajax.ajaxoptions.aspx
[2]: https://msdn.microsoft.com/en-us/library/system.web.mvc.ajax.ajaxoptions.onsuccess.aspx
[3]: https://msdn.microsoft.com/en-us/library/system.web.mvc.ajax.ajaxoptions.onfailure.aspx
[4]: https://stackoverflow.com/q/21311026/1366033
[5]: https://stackoverflow.com/q/7328977/1366033

I'm trying to get errors to show up after an ajax submit has returned an error. I'm not sure what I'm missing, but I can't get it to work. This question is basically the same thing - https://stackoverflow.com/questions/10406998/modelstate-addmodelerror-is-not-being-displayed-inside-my-view but I'm still not having any luck. My experience with Ajax and MVC (any version) is still a bit limited. Here is a very simple example, most of which I took from the previous link. 

View: test.cshtml

    @model TestProject.VisitLabResult

    @Scripts.Render("~/Scripts/jquery.unobtrusive-ajax.min.js")
    @Scripts.Render("~/Scripts/ckeditor/ckeditor.js")

    @{
        AjaxOptions ajaxOpts = new AjaxOptions
        {
            Url = Url.Action("test"),
            HttpMethod = "Post",
            LoadingElementId = "loading",
            LoadingElementDuration = 500,
            OnSuccess = "processData"
        };
    }
    @Html.ValidationMessage("CustomError")


    <div id="loading" class="load" style="display:none">
        <p>Saving...</p>
    </div>

    <table>
    @for (int item = 0; item < 10; item++)
    {
        <tr id = @item>
        @using (Ajax.BeginForm(ajaxOpts))
        {  
            @Html.ValidationSummary(true)

            @Html.AntiForgeryToken()
        
            <td>
                <input type="submit" value="Create" />
            </td>

            <td id = @(item.ToString() + "td")>
            </td>
        }
        </tr>
        }
    </table>

Controller: HomeController.cs

    public ActionResult test()
    {
        return View();
    }
    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult test(VisitLabResult vlr, int visitid = 28)
    {
        try
        {
            if (ModelState.IsValid)
            {
                if (Request.IsAjaxRequest())
                {
                    throw new Exception("error");
                }
                else
                    return View(vlr);
            }
            else
                return View(vlr);
        }
        catch (Exception ex)
        {
            ModelState.AddModelError("CustomError", "The Same test Type might have been already created, go back to the Visit page to see the available Lab Tests");
            return View(vlr);
        }
    }

Model 

    public class VisitLabResult
    {
        public int visitid { get; set; }
    }


If it is an Ajax request I throw an error and it's caught and an error is added to ModelState. That error never shows up on the page though. Am I approaching this the right way at all? Or do I need to take a different route? I appreciate any help.

MVC 4 Ajax.BeginForm and ModelState.AddModelError

If you look at the Description for the [`ShortName` property][1] on the [`Display` Attribute][2] you'll see that it has a pretty limited scope out of the box:

![Short Name Description][3]

Of course, that doesn't limit you from leveraging that value on your Model Metadata, but there aren't any native helpers that do so.

[Starting with MVC 2][4], [`ModelMetadata`][5] provides two methods to access the underlying data: `FromStringExpression` and `FromLambdaExpression`, so you don't really need to start from scratch in writing your own helper or extension method.

If you *hate* writing HTML helper methods, you can do this all inline:



    @ModelMetadata.FromLambdaExpression<RegisterModel, string>( 
                model => model.TransferDate, ViewData).ShortDisplayName} )  

But it's also perfectly valid to add an extension method for consistency of access, deduplication of code, and improved error handling


    
    public static class MvcHtmlHelpers
    {
       public static MvcHtmlString ShortNameFor<TModel, TValue>(this HtmlHelper<TModel> self, 
               Expression<Func<TModel, TValue>> expression)
       {
           var metadata = ModelMetadata.FromLambdaExpression(expression, self.ViewData);
           var name = metadata.ShortDisplayName ?? metadata.DisplayName ?? metadata.PropertyName;
    
           return MvcHtmlString.Create(string.Format(@"<span>{0}</span>", name));
       }
    }

And then use like any other helper method:



    @Html.ShortNameFor(model => model.TransferDate)




**Further Reading**:

* [How do I display the DisplayAttribute.Description attribute value?][9]
* MVC has long subsisted on custom extension methods, like [needing DisplayNameFor before it was added in MVC 4][6]  
* See this question for a quick [breakdown of the differences between `[Display(name="")]` vs. `[DisplayName("")]` attributes][7]  
* See this answer for [working with ASP.NET MVC 6 / Core 1][8]

[1]: https://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.displayattribute.shortname.aspx
[2]:https://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.displayattribute.aspx "System.ComponentModel.DataAnnotations.DisplayAttribute"
[3]: http://i.stack.imgur.com/PwPkI.png
[4]: http://bradwilson.typepad.com/blog/2009/10/aspnet-mvc-2-templates-part-2-modelmetadata.html
[5]: https://msdn.microsoft.com/en-us/library/system.web.mvc.modelmetadata.aspx "System.Web.Mvc.ModelMetadata"
[6]: https://stackoverflow.com/q/3885796/1366033
[7]: https://stackoverflow.com/q/5243665/1366033
[8]: https://stackoverflow.com/a/35294035/1366033
[9]: https://stackoverflow.com/a/6578828/1366033

Name attribute works proper, but ShortName doesn't work. 

    [Display(Name = "Date of the transfer the task", ShortName = "Trans date")]
    public DateTime TransferDate { get; set; }

Even when I delete Name attribute, ShortName is ignored ("TransferDate" displays in the column header).

In the view I do this:

    @Html.DisplayNameFor(model => model.TransferDate)



ShortName in the Display attribute (DataAnnotations)

### The Problem

As [Thomas pointed out][1], [Chris's answer][2] works in some cases, but runs into trouble when using a ViewModel because the nested properties don't enjoy the same automatic resolution.  This works if your model type is `IEnumerable<Type>`, because the DisplayNameFor lambda can still access properties on the model itself:

![Model vs Enum<Model>][3]

However, if the `ClientDetail` collection is nested inside of a ViewModel, we can't get to the item properties from the collection itself:

[![Collection inside ViewModel][4]][4]

### The Solution

As pointed out in [DisplayNameFor() From List<Object> in Model][5], your solution is actually perfectly fine.  This won't cause any issues if the collection is null because the lambda passed into `DisplayNameFor` is never actually executed. It's only uses it as an expression tree to identify the type of object.

*So any of the following will **work just fine**:*



    @Html.DisplayNameFor(model => model.Details[0].ClientNumber)

    @Html.DisplayNameFor(dummy => Model.Details.FirstOrDefault().ClientNumber)

    @{ ClientDetail dummyModel = null; }
    @Html.DisplayNameFor(dummyParam => dummyModel.ClientNumber)


### Further Explanation
If we want to see some of the fancy footwork involved in passing an expression, just look at the source code on [DisplayNameFor][6] or custom implementations like [DescriptionFor][7]. Here's an simplified example of what happens when we call DisplayNameFor with the following impossible expression:  



     @Html.DisplayNameFor3(model => model.Details[-5].ClientNumber)

![Dissecting the Expression Tree][8]

Notice how we go from `model.Details.get_Item(-5).ClientNumber` in the lambda expression, to being able to identify just the member (`ClientNumber`) without executing the expression.  From there, we just use reflection to find the `DisplayAttribute` and get its properties, in this case `Name`.


  [1]: https://stackoverflow.com/questions/24738908/best-way-to-get-table-header-names-in-mvc-4#comment58664893_24741861
  [2]: https://stackoverflow.com/questions/24738908/best-way-to-get-table-header-names-in-mvc-4#24741861
  [3]: https://i.stack.imgur.com/TFCo1.png
  [4]: https://i.stack.imgur.com/3SpDq.png
  [5]: https://stackoverflow.com/a/20808067/1366033
  [6]: https://github.com/aspnet/Mvc/blob/rel/1.0.1/src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/HtmlHelperOfT.cs#L139
  [7]: https://stackoverflow.com/a/6578828/1366033
  [8]: https://i.stack.imgur.com/vPob2.png

I'm trying to display a list of objects in a table.  I can iterate over each individual item to find it's value (using an for loop or a [DisplayTemplate][1]), but how do I abitriarily pick one to display headers for the whole group.

Here's an simplified example:

**Model**:



    public class ClientViewModel
    {
        public int Id { get; set; }
        public List<ClientDetail> Details { get; set; }
    }
    public class ClientDetail
    {
        [Display(Name="Client Number")]
        public int ClientNumber { get; set; }
        [Display(Name = "Client Forname")]
        public string Forname { get; set; }
        [Display(Name = "Client Surname")]
        public string Surname { get; set; }
    }

**View**



    @model MyApp.ViewModel.ClientViewModel
    
    @{ var dummyDetail = Model.Details.FirstOrDefault(); }

    <table>
        <thead>
            <tr>
                <th>@Html.DisplayNameFor(model => dummyDetail.ClientNumber)</th>
                <th>@Html.DisplayNameFor(model => dummyDetail.Forname)</th>
                <th>@Html.DisplayNameFor(model => dummyDetail.Surname)</th>
            </tr>
        </thead>
        <tbody>
            @for (int i = 0; i < Model.Details.Count; i++)
            {
                  <tr>
                    <td>@Html.DisplayFor(model => model.Details[i].ClientNumber)</td>
                    <td>@Html.DisplayFor(model => model.Details[i].Forname)</td>
                    <td>@Html.DisplayFor(model => model.Details[i].Surname)</td>
                </tr>
            }
        </tbody>
    </table>

*Notice*: I'm using `var dummyDetail = Model.Details.FirstOrDefault();` to get a single item whose properties I can access in `DisplayNameFor`.

* What would be the best way to access those headers ?
* Will this break if the collection is null?
* Should I just replace them with hard coded plain text labels?


  [1]: https://stackoverflow.com/a/11261629/875708

Best way to get table header names in MVC 4

Add a button to your rows like this:



    <td class="dropdown">
        <a class="btn btn-default actionButton" data-toggle="dropdown" href="#">
            Action
        </a>
    </td>

Dropdown will only automatically position itself when it is right after the `data-toggle` that's opening it.  To avoid having to write a lot of positioning code, you can just move the dropdown menu before you open it:



    //save the selector so you don't have to do the lookup everytime
    $dropdown = $("#contextMenu");

    $(".actionButton").click(function() {
        //get row ID
        var id = $(this).closest("tr").children().first().html();

        //move dropdown menu
        $(this).after($dropdown);

        //update links
        $dropdown.find(".payLink").attr("href", "/transaction/pay?id="+id);
        $dropdown.find(".delLink").attr("href", "/transaction/delete?id="+id);

        //show dropdown
        $(this).dropdown();
    });

### [Demo in jsFiddle](http://jsfiddle.net/KyleMit/K65ww/)

I have a table of transactions, and I would like to add a small button to each row. When clicked, a small drop down should appear with two menu items, something like this:



    <ul id="contextMenu" class="dropdown-menu" role="menu" style="display:none" >
        <li><a tabindex="-1" href="#">Pay</a></li>
        <li><a tabindex="-1" href="#">Delete</a></li>
    </ul>


However, my table can have between zero and potentially hundreds of rows, so repeating the code, PLUS the button that has to create the drop down, would be a lot of page size addition.

Is there a way to have that code once, and somehow, from the button click, use the same code from each row? Additionally, I would need to change the href value for each row, based on the ID of that row. So the href would actually be something like:



    \transaction\pay?id=10

With the ID changing for each row.

Re-use dropdown menu across multiple Table rows

What was happening in this case was that when the CustomErrors tried to route to the `NotFound` action on the `Error` controller, it could only supply the default constructor.  Not finding one, it bypassed the controller altogether and went directly to the error page which already had the model it wanted to pass ready.


As a small Proof of Concept, passing both parameters is definitely possible as evidenced by this example

**TestModel.vb**:



    Public Class TestModel
        Public Property ModelInfo As String
    End Class

**TestController.vb**:



    Public Class TestController :  Inherits System.Web.Mvc.Controller

        Function Index() As ActionResult
            Dim model As New TestModel With {.ModelInfo = "Hello"}
            ViewData("ViewDataInfo") = "World"
            Return View("Index", model)
        End Function

    End Class

**Test\Index.vbhtml**:

    @ModelType TestModel
    
    @Model.ModelInfo @ViewData("ViewDataInfo")

Can I use a hybrid approach that passes information in the ViewBag (C#) / ViewData (VB) but also includes a model

For example, I started passing a simple title through an error controller to an error view:



    Function NotFound() As ActionResult
        Response.StatusCode = 404
        ViewData.Add("Title", "404 Error")
        Return View("Error")
    End Function

This worked fine and the View had access to the property `@ViewData("Title")`

Then I wanted to include some of the exception information that is automatically routed by Custom Errors in the [`HandleErrorInfo`][1] object like this:



<pre><code>Function NotFound(<b>exception As HandleErrorInfo</b>) As ActionResult
    Response.StatusCode = 404
    ViewData.Add(&quot;Title&quot;, &quot;404 Error&quot;)
    ViewData.Add(&quot;Message&quot;, &quot;Sorry, the requested page could not be found.&quot;)
    Return View(&quot;Error&quot;<b>, exception</b>)
End Function
</code></pre>

Then, on the View, I declared a Model like this:

    @ModelType System.Web.Mvc.HandleErrorInfo

Now I can access properties like `@Model.Exception.Message` but my `@ViewData("Title")` has disappeared.

The [`WebViewPage(Of TModel)`][2] still has a `ViewData` property, but it looks like I can't pass anything to it from the controller unless it's explicitly in the model.

Of course, as a workaround, I could create a base class that can strongly type storage for each object, but that seems a little heavy handed when all I want to pass in through the ViewBag is the title.

Is there a way to use both ViewBag AND the Model at the same time?


[1]: http://msdn.microsoft.com/en-us/library/system.web.mvc.handleerrorinfo.aspx
[2]: http://msdn.microsoft.com/en-us/library/system.web.mvc.webviewpage.aspx

Can I pass both the ViewBag AND a Model to a View

Here are a couple solutions, but I prefer the second one.

### Solution 1 <sup>(okay)</sup>

As this appears to be a bug with the MVC Web Application project type itself, you can add the report to a different project type (like Class Library).  As described in the post [Visual Studio 2010 Report Viewer - Object Datasource][1], just create a separate library for the project and add the rdlc file there.  The data source configuration wizard should now look like this:

![data source configuration wizard][3]

### Solution 2 <sup>(better)</sup>

As figured out in [Can't see or add Website Data Sources in RDLC report in ASP.NET MVC][2], you can just add an **aspx** page anywhere to the MVC project to trick Visual Studio into pulling in the right design time libraries. 

Just do the following:

* Close all windows
* Clean & Rebuild Solution
* Add WebForm1.aspx to the Project
* Open up the RDLC file and choose a DataSource from the dropdown:

  ![DataSource Dropdown][4]


[1]: http://wraithnath.blogspot.com/2011/02/visual-studio-2010-report-viewer-object.html
[2]: https://stackoverflow.com/q/2923569/1366033
[3]: http://i.imgur.com/n44iRKu.png
[4]: http://i.imgur.com/qGkHTNu.png

I have a MVC4 application in Visual Studio 2010 which contains plenty of classes.  I'm trying to use them to pass in as the DataSource for a Report Definition Language Client ([RDLC][1]) file. But I can't access the classes from my assembly anywhere in the data source designer

According to the MSDN Walkthrough on [Using a Business Object Data Source with the ReportViewer Web Server Control in Local Processing Mode][2], I should be able to do so in the Dataset Properties page

> In the **Dataset Properties** page, in the **Data source** box, select **global**.

According to this Stackoverflow question on [How to use an Object data source in report (.rdlc)][3], when in Dataset Properties page, I should be able to create a new data source like this:

>**Creating a New Data source**: 

>* Select **Object** and click Next.
* Browse the solution tree and select the class(es) you want to bind to.
* Click Finish.

**But neither of these present as options...**

When I create a new dataset, nothing shows up under Data Source:

![DataSet Properties][4]

When I click New to create a New DataSource, I just get a connection Wizard that forces me to connect to a database:

![Data Source Configuration Wizard][5]

**Where can I add classes from my assembly?**

As a trivial example, here's an example of an object I have built into the assembly that I would expect to show up:



    Public Class Employee
        Public Property Name As String
        Public Property ID As Integer
    End Class

I would eventually like to populate this information programmatically like this:



    Dim lr As New LocalReport
    lr.ReportPath = Server.MapPath("~\Reports\Report1.rdlc")
    lr.DataSources.Add(New ReportDataSource("Data", New Employee("Kyle",27)))


[1]: http://msdn.microsoft.com/en-us/library/ms252067.aspx
[2]: http://msdn.microsoft.com/en-us/library/ms251692(v=vs.100).aspx
[3]: https://stackoverflow.com/q/3717517/1366033
[4]: http://i.imgur.com/wJgW17y.png
[5]: http://i.imgur.com/AP58Hmx.png