Question

In this post I wondered about cleaner code when internationalising an app. that leads to this second query… supposing I wanted to call a function like this:

@Html.RenderWithTags("Help",
    new Dictionary<string, string>() { "HelpPage", "@Html.ActionLink(...)" }
)

such that I look up a string in my local resource file containing embedded “tags” e.g. resource name “Help” contains:

We suggest you read our [HelpPage]
before proceeding

and then my .RenderWithTags() method will expand the tags but dynamically executing the code in the dictionary passed e.g. replace [HelpPage] with whatever @Html.ActionLink(...) produces.

I know I can use Microsoft.CSharp.CSharpCodeProvider().CreateCompiler() to compile C# code on the fly, but what about Razor code?

Answer 1

in the end, the solution turned out pretty slick. would not have been possible without SLaks, I’m much obliged for the help (though I didn’t end up using inline helpers (but thanks for the intro (they’re very cool))).
Now my page contains this:

@{
    Dictionary<string, MvcHtmlString> tokenMap = new Dictionary<string, MvcHtmlString>() {
        {"HelpPage", Html.ActionLink("help page", "Help", "Home") }
    };
}

and somewhere below I have:

@this.Resource("Epilogue", tokenMap)

To accomplish this simplicity:

public static class PageExtensions
{
    public static MvcHtmlString Resource(this WebViewPage page, string key)
    {
        HttpContextBase http = page.ViewContext.HttpContext;
        string ret = (string) http.GetLocalResourceObject(page.VirtualPath, key);
        return MvcHtmlString.Create(ret);
    }

    public static MvcHtmlString Resource(
        this WebViewPage page, string key, 
        Dictionary<string, MvcHtmlString> tokenMap
    ) {
        HttpContextBase http = page.ViewContext.HttpContext;
        string text = (string) http.GetLocalResourceObject(page.VirtualPath, key);
        return new TagReplacer(text, tokenMap).ToMvcHtmlString();
    }
}

…and:

public class TagReplacer
{
    Dictionary<string, MvcHtmlString> tokenmap;
    public string Value { get; set; } 

    public TagReplacer(string text, Dictionary<string, MvcHtmlString> tokenMap)
    {
        tokenmap = tokenMap;

        Regex re = new Regex(@"\[.*?\]", RegexOptions.IgnoreCase);
        Value = re.Replace(text, new MatchEvaluator(this.Replacer));
    }

    public string Replacer(Match m)
    {
        return tokenmap[m.Value.RemoveSet("[]")].ToString();
    }

    public MvcHtmlString ToMvcHtmlString()
    {
        return MvcHtmlString.Create(Value);
    }
}

…with a little extra help:

public static class ObjectExtensions
{
    public static string ReplaceSet(this string text, string set, string x)
    {
        for (int i = 0; i < set.Length; i++)
        {
            text = text.Replace(set[i].ToString(), x);
        }
        return text;
    }
    public static string RemoveSet(this string text, string set)
    {
        return text.ReplaceSet(set, "");
    }
}

comments or feedback on how it could have been better most welcome!