AbstractLabs: Using a builder like pattern with MVC Helper Methods

The Microsoft MVC framework is a powerful new technology but after some work I found the helper extension methods to be a little restrictive. While creating copious methods with overloads it dawned on me a string builder like pattern could be used

Here is a pseudo code example what was implemented.


//Example of builder class
using System.Web.Mvc;
 public class InlineTagBuilder : TagBuilder, IHelperBuilder
  where T : InlineTagBuilder
 {
  public InlineTagBuilder(HtmlHelper helper, string tagName, TagRenderMode mode)
   : base(tagName)
  {

   Helper = helper;
   Mode = mode;
  }

  protected TagRenderMode Mode { get; private set; }

  public HtmlHelper Helper { get; private set; }

  new public T AddCssClass(string value)
  {
   base.AddCssClass(value);
   return (T)this;
  }

  new public T MergeAttribute(string key, string value, bool replaceExisting)
  {
   base.MergeAttribute(key, value, replaceExisting);
   return (T)this;
  }

  new public T MergeAttribute(string key, string value)
  {
   base.MergeAttribute(key, value, false);
   return (T)this;
  }

  new public T MergeAttributes(IDictionary attributes, bool replaceExisting)
  {
   base.MergeAttributes(attributes, replaceExisting);
   return (T)this;
  }

  new public T MergeAttributes(IDictionary attributes)
  {
   base.MergeAttributes(attributes, false);
   return (T)this;
  }

  new public T SetInnerText(string innerText)
  {
   base.SetInnerText(innerText);
   return (T)this;
  }

  public T AppendAttributeValue(string key, string right)
  {
   string left;
   if (Attributes.TryGetValue(key, out left))
   {
    Attributes[key] = String.Concat(left, right);
   }
   else
   {
    Attributes.Add(key, right);
   }
   return (T)this;
  }

  public T InsertAttributeValue(string key, string left)
  {
   string right;
   if (Attributes.TryGetValue(key, out right))
   {
    Attributes[key] = String.Concat(left, right);
   }
   else
   {
    Attributes.Add(key, left);
   }
   return (T)this;
  }

  public T AppendEvent(string name, string body)
  {
   return AppendAttributeValue(name, body);
  }

  public T InsertEvent(string name, string body)
  {
   return InsertAttributeValue(name, body);
  }

  public T AppendStyle(string value)
  {
   if (value != null && !value.EndsWith(";"))
   {
    value = String.Concat(value, ';');
   }
   return AppendAttributeValue("style", value);
  }

  public T SetId(string id)
  {
   return MergeAttribute("id", id, true);
  }

  public T SetTitle(string title)
  {
   return MergeAttribute("title", title, true);
  }

  public T SetInnerHtml(string innerHtml)
  {
   base.InnerHtml = innerHtml;
   return (T)this;
  }

  public static implicit operator string(InlineTagBuilder builder)
  {
   return builder.ToString(builder.Mode);
  }
 }
 public class AnchorTagBuilder : InlineTagBuilder
 {
//Anchor Set Methods Here Each Method Returns This For Inline Stacking Of Method Calls...
        }
//Add extension class for easy access from the helper in the view
 public static class AnchorTagBuilderExtensions
 {
  public static AnchorTagBuilder Anchor(this HtmlHelper helper)
  {
   return new AnchorTagBuilder(helper);
  }
 }
//Example of what the view would look like
<html>
<body>

<%=Html.Anchor().MergeAttribute("href","http://www.microsoft.com").AddCssClass("footNote").AppendEvent("onclick","alert('Really Annoying Alert Box!')") %>

</body>
</html>

AbstractLabs

Thursday, July 30, 2009

Using a builder like pattern with MVC Helper Methods

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