C# – ASP.NET MVC routing with one mandatory parameter and one optional parameter

asp.net-mvcasp.net-mvc-3asp.net-mvc-routingcurl-routing

I've been working on a large MVC application over the past month or so, but this is the first time I've ever needed to define a custom route handler, and I'm running into some problems. Basically I have two parameters to pass. The first one is required and the second one is optional.

I'm following this answer here.

Here is my custom route:

routes.MapRoute(
    "MyRoute",
    "{controller}/{action}/{param1}/{param2}",
    new { 
        controller = "MyController", 
        action = "MyAction", 
        param1 = "", 
        param2 = "" // I have also tried "UrlParameter.Optional" here.
    }
);

And my action method signature:

public ActionResult MyAction(string param1, string param2)

If I try the URL http://[myserver]/MyController/MyAction/Test1/Test2 then it works like I expect it to, with param1 = "Test1" and param2 = "Test2"

If I try the URL http://[myserver]/MyController/MyAction/Test1 then both parameters are null.

Hopefully somebody can tell me what I'm doing wrong here, because I'm lost.

Best Answer

I assume that you created new route and left the default one that is very similar to yours. You should be aware that collection of routes is traversed to find first matching route. So if you have left the default one:

routes.MapRoute(
            "Default", // Route name
            "{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
        );

above your route then it will match request to http://[myserver]/My/MyAction/Test1 and call MyController.MyAction and set "Text1" to parameter named id. Which will fail because this action is not declaring one named id.

What you need to do is to move your route as first in routes list and make it more specific then it is now:

routes.MapRoute(
            "Route",
            "My/{action}/{param1}/{param2}",
            new
            {
                controller = "My",
                action = "MyAction",
                param1 = "",
                param2 = ""
            });

This will force all traffic routed trough My to match this route.

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common

C# – How to handle multiple submit buttons in ASP.NET MVC Framework

Here is a mostly clean attribute-based solution to the multiple submit button issue based heavily on the post and comments from Maarten Balliauw.

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class MultipleButtonAttribute : ActionNameSelectorAttribute
{
    public string Name { get; set; }
    public string Argument { get; set; }

    public override bool IsValidName(ControllerContext controllerContext, string actionName, MethodInfo methodInfo)
    {
        var isValidName = false;
        var keyValue = string.Format("{0}:{1}", Name, Argument);
        var value = controllerContext.Controller.ValueProvider.GetValue(keyValue);

        if (value != null)
        {
            controllerContext.Controller.ControllerContext.RouteData.Values[Name] = Argument;
            isValidName = true;
        }

        return isValidName;
    }
}

razor:

<form action="" method="post">
 <input type="submit" value="Save" name="action:Save" />
 <input type="submit" value="Cancel" name="action:Cancel" />
</form>

and controller:

[HttpPost]
[MultipleButton(Name = "action", Argument = "Save")]
public ActionResult Save(MessageModel mm) { ... }

[HttpPost]
[MultipleButton(Name = "action", Argument = "Cancel")]
public ActionResult Cancel(MessageModel mm) { ... }

Update: Razor pages looks to provide the same functionality out of the box. For new development, it may be preferable.

Best Answer

Related Solutions

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

For MVC v5 use EnumHelper

For MVC 5 and lower

C# – How to handle multiple submit buttons in ASP.NET MVC Framework

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