Asp.net-mvc – ASP.NET MVC – TempData – Good or bad practice

asp.net-mvctempdata

I'm using the AcceptVerbs method detailed in Scott Gu's Preview 5 blog post for dealing with form entries in ASP.NET MVC:

User gets an empty form via GET
User posts the filled in form via POST to the same Action
The Action validates data, takes appropriate action, and redirects to a new view

So I don't have to use TempData. That said, I now have to add a 'confirm' step to this process, and it seems to require the use of TempData.

For some reason, I have an aversion to using TempData — that it is something to be designed around.

Is this at all a valid concern, or am I making it up?

Best Answer

No need to have an aversion to TempData... But if not used correctly it could surely be an indication of poor design. If you are using RESTful URL's, TempData is a best practice for transfering messages from your POST Actions to your GET Actions. Consider this:

You have a form at URL Products/New. The form Posts to Products/Create, which validates the form and creates the Product, On Success the Controller redirects to URL Products/1 and on error would redirect back to products/New to display Error Messages.

Products/1 is just the standard GET action for the product, but we would like a message to display indicating the insert was a success. TempData is perfect for this. Add the message to TempData in the Post Controller and put some if logic in the view and your done.

On failure I've been adding the values entered in the formCollection and a collection of error Messages to TempData in the Post Action, and redirecting to the intial Action Prodcuts/New. I've added logic to the view to populate the form inputs with the previously entered values along with any error messages. Seems nice and clean to me!

Related Solutions

Asp.net-mvc – Compile Views in ASP.NET MVC

From the readme word doc for RC1 (not indexed by google)

ASP.NET Compiler Post-Build Step

Currently, errors within a view file are not detected until run time. To let you detect these errors at compile time, ASP.NET MVC projects now include an MvcBuildViews property, which is disabled by default. To enable this property, open the project file and set the MvcBuildViews property to true, as shown in the following example:

<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <MvcBuildViews>true</MvcBuildViews>
  </PropertyGroup>

Note Enabling this feature adds some overhead to the build time.

You can update projects that were created with previous releases of MVC to include build-time validation of views by performing the following steps:

Open the project file in a text editor.
Add the following element under the top-most <PropertyGroup> element: <MvcBuildViews>true</MvcBuildViews>
At the end of the project file, uncomment the <Target Name="AfterBuild"> element and modify it to match the following:

<Target Name="AfterBuild" Condition="'$(MvcBuildViews)'=='true'">
    <AspNetCompiler VirtualPath="temp" PhysicalPath="$(ProjectDir)\..\$(ProjectName)" />
</Target>

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

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