Best practice for ASP.NET MVC resource files

Question

What are the best usage of the following resource files.

1. Properties → Resources (Phil used this resource for localization in DataAnnotation)
2. App_GlobalResources folder
3. App_LocalResources folder

I also would like to know what is the difference between (1) and (2) in asp.net mvc application.

Solution 1

You should avoid App_GlobalResources and App_LocalResources. Like Craig mentioned, there are problems with App_GlobalResources/App_LocalResources because you can't access them outside of the ASP.NET runtime. A good example of how this would be problematic is when you're unit testing your app.

K. Scott Allen blogged about this a while ago. He does a good job of explaining the problem with App_GlobalResources in ASP.NET MVC here.

Solution 2

If you go with the recommended solution (1) (i.e. as in K. Scott Allen's blog):

For those of you trying to use explicit localization expressions (aka declarative resource binding expressions), e.g. <%$ Resources, MyResource:SomeString %>

public class AppResourceProvider : IResourceProvider
{
    private readonly string _ResourceClassName;
    ResourceManager _ResourceManager = null;

    public AppResourceProvider(string className)
    {
        _ResourceClassName = className;
    }

    public object GetObject(string resourceKey, System.Globalization.CultureInfo culture)
    {
        EnsureResourceManager();
        if (culture == null)
        {
            culture = CultureInfo.CurrentUICulture;
        }
        return _ResourceManager.GetObject(resourceKey, culture);
    }

    public System.Resources.IResourceReader ResourceReader
    {
        get
        {
            // Not needed for global resources
            throw new NotSupportedException();
        }
    }

    private void EnsureResourceManager()
    {
        var assembly = typeof(Resources.ResourceInAppToGetAssembly).Assembly;
        String resourceFullName = String.Format("{0}.Resources.{1}", assembly.GetName().Name, _ResourceClassName);
        _ResourceManager = new global::System.Resources.ResourceManager(resourceFullName, assembly);
        _ResourceManager.IgnoreCase = true;
    }
}

public class AppResourceProviderFactory : ResourceProviderFactory
{
    // Thank you, .NET, for providing no way to override global resource providing w/o also overriding local resource providing
    private static Type ResXProviderType = typeof(ResourceProviderFactory).Assembly.GetType("System.Web.Compilation.ResXResourceProviderFactory");
    ResourceProviderFactory _DefaultFactory;

    public AppResourceProviderFactory()
    {
        _DefaultFactory = (ResourceProviderFactory)Activator.CreateInstance(ResXProviderType);
    }

    public override IResourceProvider CreateGlobalResourceProvider(string classKey)
    {
        return new AppResourceProvider(classKey);
    }

    public override IResourceProvider CreateLocalResourceProvider(string virtualPath)
    {
        return _DefaultFactory.CreateLocalResourceProvider(virtualPath);
    }
}

Then, add this to your web.config:

    <globalization requestEncoding="utf-8" responseEncoding="utf-8" fileEncoding="utf-8" culture="en-US" uiCulture="en"
                   resourceProviderFactoryType="Vendalism.ResourceProvider.AppResourceProviderFactory" />

Solution 3

Properties → Resources can be seen outside of your views and strong types are generated when you compile your application.

App_* is compiled by ASP.NET, when your views are compiled. They're only available in the view. See this page for global vs. local.

Comments

[ProfK]

What is Resources.ResourceInAppToGetAssembly? It doesn't compile and I can't find any reference to it but in this example? Is it a pseudonym for the actual resources class you're using?