Develop Reference

How can I capture the #Html.DropDownListFor selected value?

I am using MVC5, Razor, Entity Framework, C#. I am trying to pass a value of a dorpdown list using a link.
my model is
public class TestVM
{
public string TheID { get; set; }
}
I am loading an enum into a IEnumerable<SelectListItem>.
My enum is
public enum DiscountENUM
{
SaleCustomer,
SaleCustomerCategory,
SaleProduct,
SaleProductCategory,
SaleCustomerAndProduct,
SaleCustomerAndProductCategory,
SaleCustomerCategoryAndProductCategory,
PurchaseVendor,
PurchaseVendorAndProduct,
PurchaseVendorAndProductCategory,
PurchaseProduct,
PurchaseProductCategory,
Unknown
}
I am using the index method of the home controller
public ActionResult Index()
{
ViewBag.ListOfDiscounts = SelectListDiscountENUM();
TestVM d = new TestVM();
return View(d);
}
Where I load the ListOfDiscounts using:
private IEnumerable<SelectListItem> SelectListDiscountENUM()
{
List<SelectListItem> selectList = new List<SelectListItem>();
var listOfEnumValues = Enum.GetValues(typeof(DiscountENUM));
if (listOfEnumValues != null)
if (listOfEnumValues.Length > 0)
{
foreach (var item in listOfEnumValues)
{
SelectListItem sVM = new SelectListItem();
sVM.Value = item.ToString();
sVM.Text = Enum.GetName(typeof(DiscountENUM), item).ToString();
selectList.Add(sVM);
}
}
return selectList.OrderBy(x => x.Text).AsEnumerable();
}
My create method which is called from the view is
public ActionResult Create(TestVM d, string TheID)
{
return View();
}
My Index view is
#model ModelsClassLibrary.Models.DiscountNS.TestVM
<div>#Html.ActionLink("Create New", "Create", new { TheID = Model.TheID})</div>
<div>
#Html.DropDownListFor(x => x.TheID, #ViewBag.ListOfDiscounts as IEnumerable<SelectListItem>, "--- Select Discount Type ---", new { #class = "form-control" })
</div>
The problem is in the following line in the View
<div>#Html.ActionLink("Create New", "Create", new { TheID = Model.TheID })</div>
I have tried adding a model with the name of the field as "TheID"... no luck. Also, added a string field in the parameter, no luck. I looked at the FormControl object, and there was nothing in it either! I suspect something has to be added at the Route level in the helper, but I don't know what.
Model.TheID is always null. Even when I select an item in the DropDownListFor.
Does anyone have an idea how I can capture the select value of the DropDownListFor and send it into the Html.ActionLink TheID?

Render bootstrap dropdown menu with in c# MVC3 Html.ActionLink

Therefore I faced an issue with MVC ActionLink and bootstrap dropdown. I succeeded with simple menu extension where I passed such a parameters like strings and one bool. But now I am trying to make my own extension which could generate Bootstrap Dropdown and add selected css class to parent of the dropdown - "ONEofTHEdropdownITEMSselected" - when one of those items in dropdown is selected (when selecting dropdown item it routes to different controller there fore can be few or more controllers):
Dropdown <b class="caret"></b>
and
<li class="dropdown">
Dropdown <b class="caret"></b>
<ul class="dropdown-menu">
<li>Action1</li>
<li>Action2</li>
</ul>
</li>
Below is my UI/MenuExtensions.cs what I am trying to achieve - to pass two parameters which could generate the bootstrap dropdown and I can manually insert new menu items in that dropdown.
public static class MenuExtensions
{
public static MvcHtmlString MenuItem(
this HtmlHelper htmlHelper,
string text,
string action,
string controller,
string cssClass = "item",
bool isController = false
)
{
var li = new TagBuilder("li");
var routeData = htmlHelper.ViewContext.RouteData;
var currentAction = routeData.GetRequiredString("action");
var currentController = routeData.GetRequiredString("controller");
if ((string.Equals(currentAction, action, StringComparison.OrdinalIgnoreCase) || isController) &&
string.Equals(currentController, controller, StringComparison.OrdinalIgnoreCase))
li.AddCssClass("am-selected");
li.InnerHtml = htmlHelper.ActionLink(text, action, controller, new { Area = "" }, new { #class = cssClass }).ToHtmlString();
return MvcHtmlString.Create(li.ToString());
}
public static MvcHtmlString SelectMenu(
this HtmlHelper htmlHelper,
string cssClass,
SelectMenuItem[] menuItems
)
{
TagBuilder list = new TagBuilder("li")
{
InnerHtml = ""
};
string currentAction = htmlHelper.ViewContext.RouteData.GetRequiredString("action");
string currentController = htmlHelper.ViewContext.RouteData.GetRequiredString("controller");
foreach (SelectMenuItem menuItem in menuItems)
{
TagBuilder li = new TagBuilder("li")
{
InnerHtml = htmlHelper.ActionLink(menuItem.Text, menuItem.Action, menuItem.Controller, null, new { }).ToHtmlString()
};
ul.InnerHtml += li.ToString();
}
return MvcHtmlString.Create(list.ToString());
}
}
Here is the external class
public class SelectMenuItem
{
public string Text { get; set; }
public string Action { get; set; }
public string Controller { get; set; }
public bool IsVisible { get; set; }
public SelectMenuItem()
{
IsVisible = true;
}
}
After that my html looks like this.
#Html.SelectMenu("dropdown", new []{
new SelectMenuItem{ Text = "ViewOne", Controller = "Controller1", Action = "index", IsVisible = SystemUser.Current().IsAdmin},
new SelectMenuItem{ Text = "ViewTwo", Controller = "Controller2", Action = "index"}
});
The problem is SelectMenu renders only this:
<li></li>

No need to reinvent the wheel. With TwitterBootstrapMVC desired output is achieved with the following syntax:
#using (var dd = Html.Bootstrap().Begin(new DropDown("Dropdown").SetLinksActiveByControllerAndAction()))
{
#dd.ActionLink("Action1", "index", "controller1")
#dd.ActionLink("Action2", "index", "controller2")
}
Notice the extension method SetLinksActiveByControllerAndAction(). That's what makes links active based on current controller/action.
Disclaimer: I'm the author of TwitterBootstrapMVC.
You need to purchase a license if working with Bootstrap 3. For Bootstrap 2 it's free.

ASP.NET MVC Action Argument Dictionary Removing Elements with # in them

I have a controller action with a Dictionary argument:
[HttpPost]
[AllowCrossSiteJson]
public ActionResult MyActionMethod(Dictionary<string, string> EnteredValues)
When I try to invoke this method using JSON, the dictionary entries with an # sign in them get removed from the list. For instance, if I invoke the method using this JSON:
{
"EnteredValues": {
"__EVENTTARGET": "",
"__EVENTARGUMENT": "",
"__LASTFOCUS": "",
"ctl00$txtContractQuickSearch": "Contract Search",
"ctl00$txtAdvisorQuickSearch": "Rep Search",
"New Business.#StartDate": "1/1/2013",
"New Business.#EndDate": "10/25/2013",
"New Business.#RegionCode": "All",
"ShowChart": "on",
"txtSearchContractNumber": "Contract Number",
"txtSearchContractFirstName": "Owner First Name",
"txtSearchContractLastName": "Owner Last Name",
"DXScript": "1_42"
}
}
The 3 "New Business" entries get removed because they have an # sign in them. Why is this happening and how do I fix it?

Try to wrap your dictionary entries with an # sign with single quotes.
"'New Business.#StartDate'": "1/1/2013"
Or
"New Business.'#StartDate'": "1/1/2013"

After looking into model binders and dynamic JSON objects, I was able to work around this issue by creating my own Dictionary model binder:
public class DictionaryStringModelBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
Dictionary<string, string> model = new Dictionary<string, string>();
string contentType = controllerContext.RequestContext.HttpContext.Request.ContentType;
if (contentType != null && contentType.Contains("application/json"))
{
JavaScriptSerializer serializer = new JavaScriptSerializer();
controllerContext.RequestContext.HttpContext.Request.InputStream.Position = 0;
string content = new StreamReader(controllerContext.RequestContext.HttpContext.Request.InputStream).ReadToEnd();
var dynamicContent = Json.Decode(content);
foreach (string property in dynamicContent.GetDynamicMemberNames())
{
if (property == bindingContext.ModelName)
{
foreach (string dictionaryProperty in dynamicContent[property].GetDynamicMemberNames())
{
model.Add(dictionaryProperty, dynamicContent[property][dictionaryProperty]);
}
break;
}
}
}
else
{
model = (Dictionary<string, string>)ModelBinders.Binders.DefaultBinder.BindModel(controllerContext, bindingContext);
}
return model;
}
}
Then inside Globals.asax:Application_Start, I bound this model binder like so:
ModelBinders.Binders[typeof(Dictionary<string, string>)] = new DictionaryStringModelBinder();
My dictionaries are now property being deserialized even if the key has an # in it. Note that this will only work if the dictionary is in the root of both the action arguments (i.e. not inside a class within an action argument) and the JSON.

RouteValueDictionary to HtmlAttributes

I know I can add html attributes to my tag by doing something like:
var htmlAttributes = new RouteValueDictionary { { "data-foo", "bar" } };
var tag = new TagBuilder("div");
tag.MergeAttributes(htmlAttributes );
#tag
Output:
<div data-foo="bar"></div>
I wonder if I can add attributes in a similar way by using markup instead of a tag builder. Maybe something like:
var htmlAttributes = new RouteValueDictionary { { "data-foo", "bar" } };
<div #htmlAttributes.ToHtmlAttributes() ></div>
Expected output:
<div data-foo="bar"></div>
Clearly, I wouldn't be able to handle merge conflicts this way. However, I think it's worth it because the second way is so much more readable.

You can write your own extension method:
namespace SomeNamespace
{
public static class RouteValueDictionaryExtensions
{
public static IHtmlString ToHtmlAttributes(this RouteValueDictionary dictionary)
{
var sb = new StringBuilder();
foreach (var kvp in dictionary)
{
sb.Append(string.Format("{0}=\"{1}\" ", kvp.Key, kvp.Value));
}
return new HtmlString(sb.ToString());
}
}
}
which will be used exactly how you've described:
#using SomeNamespace
#{
var htmlAttributes = new RouteValueDictionary
{
{"data-foo", "bar"},
{"data-bar", "foo"}
};
}
<div #htmlAttributes.ToHtmlAttributes()> </div>
the result is:
<div data-foo="bar" data-bar="foo" > </div>
Edit:
If you want to use TagBuilder, you can alternatively write another extension which uses it internally:
public static IHtmlString Tag(this HtmlHelper helper,
RouteValueDictionary dictionary,
string tagName)
{
var tag = new TagBuilder(tagName);
tag.MergeAttributes(dictionary);
return new HtmlString(tag.ToString());
}
and the usage shown below below gives the same output html as previously:
#Html.Tag(htmlAttributes, "div")

Dynamic validation in ASP MVC

For a project at work I'm trying to create a process that lets a user dynamically create a form that other users could then fill out the values for. I'm having trouble figuring out how to go about getting this to play nice with the built in model binding and validation with ASP MVC 3, though.
Our view model is set up something like this. Please note that I've over simplified the example code:
public class Form
{
public FieldValue[] FieldValues { get; set; }
}
public class Field
{
public bool IsRequired { get; set; }
}
public class FieldValue
{
public Field Field { get; set; }
public string Value { get; set; }
}
And our view looks something like:
#model Form
#using (Html.BeginForm("Create", "Form", FormMethod.Post))
{
#for(var i = 0; i < Model.Fields.Count(); i++)
{
#Html.TextBoxFor(_ => #Model.Fields[i].Value)
}
<input type="submit" value="Save" name="Submit" />
}
I was hoping that we'd be able to create a custom ModelValidatorProvider or ModelMetadataProvider class that would be able to analyze a FieldValue instance, determine if its Field.IsRequired property is true, and then add a RequiredFieldValidator to that specific instance's validators. I'm having no luck with this, though. It seems that with ModelValidatorProvider(and ModelMetadataProvider) you can't access the parent container's value(ie: GetValidators() will be called for FieldValue.Value, but there's no way from there to get the FieldValue object).
Things I've tried:
In the ModelValidatorProvider, I've tried using
ControllerContext.Controller.ViewData.Model, but that doesn't work if
you have nested types. If I'm trying to figure out the validators
Form.FieldValues[3], I have no idea which FieldValue to use.
I tried using a custom ModelMetadata that tries to use the internal
modelAccessor's Target property to get the parent, but this also
doesn't work if you have a nested type. Somewhere internal to MVC, an
expression like the one in my example will result in the Target being
the Model's type(Form), not FieldValue. So I get the same problem as
above where I have no idea what instance of FieldValue to compare
against.
A class-level validation attribute that I could put on the FieldValue
class itself, but this only gets called during server validation. I
need client-side validation, too.
Is what I'm trying to do even possible in MVC? Or is there something I'm missing entirely?

One possibility is to use a custom validation attribute.
But before getting into the implementation I would like to point out a potential flaw in your scenario. The IsRequired property is part of your model. This means that when the form is submitted its value must be known so that we conditionally apply the required rule to the corresponding property. But for this value to be known when the form is submitted this means that it must be either part of the form (as a hidden or standard input field) or must be retrieved from somewhere (datastore, ...). The problem with the first approach is obvious => hidden field means that the user can set whatever value he likes, so it's no longer a real validation because it is the user that decides which field is required.
This warning being said, let's suppose that you trust your users and decide to take the hidden field approach for storing the IsRequired value. Let's see how a sample implementation:
Model:
public class Form
{
public FieldValue[] Fields { get; set; }
}
public class FieldValue
{
public Field Field { get; set; }
[ConditionalRequired("Field")]
public string Value { get; set; }
}
public class Field
{
public bool IsRequired { get; set; }
}
Controller:
public class HomeController : Controller
{
public ActionResult Index()
{
var model = new Form
{
Fields = new[]
{
new FieldValue { Field = new Field { IsRequired = true }, Value = "" },
new FieldValue { Field = new Field { IsRequired = true }, Value = "" },
new FieldValue { Field = new Field { IsRequired = false }, Value = "value 3" },
}
};
return View(model);
}
[HttpPost]
public ActionResult Index(Form model)
{
return View(model);
}
}
View:
#model Form
#using (Html.BeginForm())
{
#Html.EditorFor(x => x.Fields)
<input type="submit" value="Save" name="Submit" />
}
ConditionalRequiredAttribute:
public class ConditionalRequiredAttribute : ValidationAttribute, IClientValidatable
{
private RequiredAttribute _innerAttribute = new RequiredAttribute();
private readonly string _fieldProperty;
public ConditionalRequiredAttribute(string fieldProperty)
{
_fieldProperty = fieldProperty;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var containerType = validationContext.ObjectInstance.GetType();
var field = containerType.GetProperty(_fieldProperty);
if (field == null)
{
return new ValidationResult(string.Format("Unknown property {0}", _fieldProperty));
}
var fieldValue = (Field)field.GetValue(validationContext.ObjectInstance, null);
if (fieldValue == null)
{
return new ValidationResult(string.Format("The property {0} was null", _fieldProperty));
}
if (fieldValue.IsRequired && !_innerAttribute.IsValid(value))
{
return new ValidationResult(this.ErrorMessage, new[] { validationContext.MemberName });
}
return ValidationResult.Success;
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var rule = new ModelClientValidationRule()
{
ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
ValidationType = "conditionalrequired",
};
rule.ValidationParameters.Add("iserquiredproperty", _fieldProperty + ".IsRequired");
yield return rule;
}
}
Associated unobtrusive adapter:
(function ($) {
$.validator.unobtrusive.adapters.add('conditionalrequired', ['iserquiredproperty'], function (options) {
options.rules['conditionalrequired'] = options.params;
if (options.message) {
options.messages['conditionalrequired'] = options.message;
}
});
$.validator.addMethod('conditionalrequired', function (value, element, parameters) {
var name = $(element).attr('name'),
prefix = name.substr(0, name.lastIndexOf('.') + 1),
isRequiredFiledName = prefix + parameters.iserquiredproperty,
requiredElement = $(':hidden[name="' + isRequiredFiledName + '"]'),
isRequired = requiredElement.val().toLowerCase() === 'true';
if (!isRequired) {
return true;
}
return value && value !== '';
});
})(jQuery);