Question

I have to write a lot of code that’s going to generate Knockout JS templates from classes.

Say something like this…

 <li><span>Surname</span> <span data-bind="text: SURNAME"></span></li>

which I’d like to invoke in a razor template with something like…

 @className.DisplayMeFor(c=>c.SURNAME)

or even

 @DisplayMeFor<className>(c=>c.SURNAME)

but I’m really stuck knowing where to start. I clearly need to do some reading up on generics but I thought it would be something like this…

public static class HtmlExtensions
{
    public static MvcHtmlString DisplayMeFor<TModel, TValue>(this TModel htmlHelper,   Expression<Func<TModel, TValue>> expression)
    {
        var s = expression.ToString(); //Clearly need a lot more code here to get name, DisplayName etc
        return MvcHtmlString.Create(s);
    }
}

but that’s not providing an extension to the model (i.e. @vmAppeal.DisplayMeFor(… does not compile.

Any pointers please ?

Answer 1

The solution I came up with was

public static class Exts
{
    private const string Input = @"<div><span>{0} : </span><input data-bind='value: {1}'></input></div>";
    private const string Display = @"<div><span>{0} : </span><span data-bind='text: {1}'></span></div>";
    private const string DatePicker = @"<div><span>{0} : </span><input data-bind='datepicker: {1}, datepickerOptions: {{  dateFormat: ""dd/mm/yy""}}' /></div>";

    public static MvcHtmlString TemplateFor<TModel>(Expression<Func<TModel, object>> expression, bool edit) where TModel : class  , new()
    {
        var data = new ViewDataDictionary<TModel>();
        var metadata = ModelMetadata.FromLambdaExpression(expression, data);
        var typ = metadata.ModelType;

        var s = edit? Input: Display;
        if (typ == typeof(System.DateTime) ||typ == typeof(System.DateTime?))
        {
            s = edit ? DatePicker : Display;
        }
        return MvcHtmlString.Create(string.Format(s, metadata.GetDisplayName(), metadata.PropertyName));
    }
}

which is called

@(Exts.TemplateFor<MyClass>(a=>a.MyField,true))