Blog: The Sitecore Gutter.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Sitecore.Shell.Applications.ContentEditor.Gutters;
using Sitecore.Data.Items;
using Sitecore.Diagnostics;
using Sitecore.Data.Fields;
using Sitecore.Rules;

namespace RuleBasedGutterRenderer
{
    public class RuleBased : GutterRenderer
    {
        protected override GutterIconDescriptor GetIconDescriptor(Item item)
        {
            Assert.ArgumentNotNull(item, "item");
            string datasource = Parameters["datasource"];
            string fieldName = Parameters["fieldname"];
            Assert.IsNotNull(datasource, "No datasource set on this rule based gutter renderer");
            Assert.IsNotNull(fieldName, "No field name set on this rule based gutter renderer");
            Item dsItem = item.Database.GetItem(datasource);

            Assert.IsNotNull(dsItem, string.Format("Datasource '{0}' is not valid", datasource));
            Assert.IsNotNull(dsItem.Fields[fieldName], string.Format("Item '{0}' does not have a field named '{1}'", item.ID, fieldName));

            RuleList<RuleContext> rules = RuleFactory.GetRules<RuleContext>(new Item[] { dsItem }, fieldName);
            RuleContext ctx = new RuleContext() { Item = item };
            RuleStack ruleStack = new RuleStack();
            foreach (Rule<RuleContext> rule in rules.Rules)
            {
                rule.Condition.Evaluate(ctx, ruleStack);
            }

            if ((bool)ruleStack.Pop())
            {
                GutterIconDescriptor descriptor = new GutterIconDescriptor();
                descriptor.Icon = dsItem.Appearance.Icon;
                descriptor.Tooltip = string.Format("This item matches the rules as configured in {0} (field={1}).", dsItem.Paths.FullPath, fieldName);
                return descriptor;
            }

            return null;
        }
    }
}