Sitecore How-To: Add A Computed Index Field to Lucene

• Overview
• How-To
• Step-by-step guide

Overview

This is an article in a series of Sitecore how-to articles. These articles are meant to be quick guides to accomplish various tasks within Sitecore. The how-to articles have proven to be very helpful internally at One North Interactive https://www.onenorth.com. These articles assume working Sitecore knowledge. I just wanted to share the articles with the community. Hopefully you find them helpful.

How-To

Computed index fields allow you to index values that are calculated during the indexing process.

Implementation may vary depending on Sitecore version. The below applies to Sitecore 7.0 to 9.0.

Step-by-step guide

1. Create a class that derives from IComputedIndexField, which will contain the logic for the computed index field.

    using Sitecore.ContentSearch;
    using Sitecore.ContentSearch.ComputedFields;
    using Sitecore.Data.Items;
    using Sitecore.Diagnostics;
       
    namespace Website.ComputedFields
    {
        public class MyComputedIndexField : IComputedIndexField
        {
            public string FieldName { get; set; }
       
            public string ReturnType { get; set; }
       
            public object ComputeFieldValue(IIndexable indexable)
            {
                Assert.ArgumentNotNull(indexable, "indexable");
                SitecoreIndexableItem scIndexable = indexable as SitecoreIndexableItem;
                Item item = (Item)scIndexable;
                Sitecore.Context.Database = item.Database;
       
                if (item != null)
                {
                    // This is for indexing the master database. We dont not want to index unpublishable items.
                    if (item.Publishing.IsPublishable(System.DateTime.Now, false))
                    {
                        // TODO: computed logic goes here. Return whatever value you want to be indexed.
                        // Caution: performance is critical. Keep your logic simple and stay away from ORMs if you can.
                    }
                }
       
                return null;
            }
        }
    }
   

2. Add the new computed index field to the configuration.

   1. Add the new field to the raw:AddFieldByFieldName section. This is where you will specify the storage type, index type, etc. The details of those settings are not covered in this article.

       <fieldNames hint="raw:AddFieldByFieldName">
         <field fieldName="myComputedIndexFieldName" storageType="YES" indexType="TOKENIZED" vectorType="NO" boost="1f" type="System.String" settingType="Sitecore.ContentSearch.LuceneProvider.LuceneSearchFieldConfiguration, Sitecore.ContentSearch.LuceneProvider" />
       </fieldNames>
      

   2. Add the new field to the fields hint=”raw:AddComputedIndexField” section. This is where you will specify the class that contains the computed logic.

       <fields hint="raw:AddComputedIndexField">
         <field fieldName="myComputedIndexFieldName">Website.ComputedFields.MyComputedIndexField, Website</field>
       </fields>