How to create a fluent style MVC 2 Html.Helper?

Question

Hi! Could someone point me in the right direction on how would I go about creating htmlhelpers that you could call in the view something like the code below.

   <% using (Html.BeginSvg())
   {%>
   <% using (Html.BeginGroup("Group1")) {%>
        <%= Html.SvgLine("Line1").Class("blueLine").Style("stroke-width:2px").X1(25).Y1(25).X2(25).Y2(25).Transform().Scale(-2)%>
        <%= Html.SvgLine("Line1").Class("blueLine").Style("stroke-width:2px").X1(100).Y1(25).X2(100).Y2(125).Transform().Scale(-2)%>
   <%} %>
   <%= Html.SvgRect("box").Class("redBox").X(12).Y(10).Width(234).Height(200) %>
<%} %>

Is it possible? is it sane? :) is there something like this already implemented?

Cheers Si

Answer 1

I don't know if it's been done but Fluent Interfaces are awesome...here's a very basic implementation for you.

public static class SvgLineHelper {
    public static SvgLine SvgLine(this HtmlHelper helper, string name) {
        return new SvgLine(name);
    }
}

public class SvgLine {
    string _name;
    int _x;
    int _y;
    int _width;
    int _height;
    IList<string> _styles;

    public SvgLine(string name) {
        _styles = new List<string>();
        _name = name;
    }

    public static SvgLine Create(string name) {
        return new SvgLine(name);
    }

    public SvgLine X(int x) {
        this._x = x;
        return this;
    }

    public SvgLine Width(int width) {
        this._width = width;
        return this;
    }

    public SvgLine Style(string style) {
        this._styles.Add(style);
        return this;
    }

    public override string ToString() {
        //create your string from this object here
        return string.Format("x:{0}, width:{1}, style:{2}", _x, _width, _styles[0]);
    }
}

And here's how you use it in your html

<% Html.SvgLine("test").X(100).Width(50).Style("stroke-width:2px").ToString() %>

You have to call the tostring method as the last call (or another method that finalizes your fluent interface - the one that returns a string representation of your object)

Answer 2

Html helpers called with <%= must return string or MvcHtmlString. So the API you propose won't work unless you add a ToString or something at the end, like:

<%= Html.SvgLine("Line1").Class("blueLine").ToMvcHtmlString() %>

Alternately, you could pass a fluent config object as an argument to SvgLine:

<%= Html.SvgLine(With().Name("Line1").Class("blueLine")) %>

Either way would work. Pick whichever you like.