Coveo Custom Computed Field

CoveoCustomComputedField.cs

using System;
using Sitecore.ContentSearch;
using Sitecore.Data.Fields;
using Sitecore.Data.Items;
using Sitecore.ContentSearch.Diagnostics;
using Sitecore.ContentSearch.ComputedFields;

namespace Balaone.Coveo {
    public abstract class BaseCoveoComputedField : IComputedIndexField
    {
        public string FieldName { get; set; }
        public string ReturnType { get; set; }
        public abstract Object ComputeFieldValue(IIndexable indexable);
        protected Item GetItemFromIndexable(IIndexable indexable)
        {
            try
            {
                string typeName = GetType().Name;
                if (indexable == null || !(indexable is SitecoreIndexableItem sitecoreIndexable))
                {
                    CrawlingLog.Log.Warn($"Indexable is null or non indexable for field {typeName}");
                }
                else if (indexable != null)
                {
                    return sitecoreIndexable.Item;
                }
            }
            catch (Exception ex)
            {
                CrawlingLog.Log.Error($"Error in GetItemFromIndexable method for field: {typeName}", ex);
            }
            return null;
        }
    }

    public class MyComputedField : BaseCoveoComputedField
    {
        public override object ComputeFieldValue(IIndexable indexable)
        {
            var item = GetItemFromIndexable(indexable);
            var isInherited = item?.InheritsTemplate("YOUR TEMPLATE GUID");
            if (item == null || !isInherited)
            {
                return null;
            }

            TextField field = item.Fields["MyFieldName"];
            if (field == null || string.IsNullOrEmpty(field.Value))
            {
                return null;
            }

            return field.Value;
        }
    }
}