gistfile1.txt

//references
//http://www.sitecore.net/Learn/Blogs/Technical-Blogs/John-West-Sitecore-Blog/Posts/2013/05/Sitecore-7-Enable-Default-Computed-Index-Fields.aspx
//http://kamsar.net/index.php/2014/05/indexing-subcontent/
//http://www.techphoria414.com/Blog/2013/November/Sitecore-7-Computed-Fields-All-Templates-and-Datasource-Content

public class SubcontentField : IComputedIndexField
    {
        public string FieldName { get; set; }
        public string ReturnType { get; set; }

        public object ComputeFieldValue(IIndexable indexable)
        {
            try
            {
                var sitecoreIndexable = indexable as SitecoreIndexableItem;

                if (sitecoreIndexable == null)
                {
                    return null;
                }

                // find renderings with datasources set
                var customDataSources = ExtractRenderingDataSourceItems(sitecoreIndexable.Item);

                // extract text from data sources
                var contentToAdd = customDataSources.SelectMany(GetItemContent).ToList();

                if (contentToAdd.Count == 0)
                {
                    return null;
                }

                return string.Join(" ", contentToAdd);
            }
            catch (Exception ex)
            {
                Log.Error($"An error occurred when indexing {indexable.Id}: {ex.Message}", ex, this);
            }
            return null;
        }

        /// <summary>
        /// Finds all renderings on an item's layout details with valid custom data sources set and returns the data source items.
        /// </summary>
        protected virtual IEnumerable<Item> ExtractRenderingDataSourceItems(Item baseItem)
        {
            //azadeh test
            //if (baseItem.ID == ID.Parse("{6A139D21-0EBB-469C-94A8-FC1C40E45EB9}"))
            //{
            //    Debugger.Break();
            //}

            //rendering
            var currentLayoutXml = LayoutField.GetFieldValue(baseItem.Fields[FieldIDs.LayoutField]);
            //final rendering
            var finalLayoutXml = LayoutField.GetFieldValue(baseItem.Fields[FieldIDs.FinalLayoutField]);

            var layoutXml = !string.IsNullOrEmpty(finalLayoutXml) ? finalLayoutXml: currentLayoutXml;

            if (string.IsNullOrEmpty(layoutXml))
            {
                yield break;
            }

            var layout = LayoutDefinition.Parse(layoutXml);

            // loop over devices in the rendering
            for (var deviceIndex = layout.Devices.Count - 1; deviceIndex >= 0; deviceIndex--)
            {
                var device = layout.Devices[deviceIndex] as DeviceDefinition;

                if (device == null)
                {
                    continue;
                }

                // loop over renderings within the device
                for (var renderingIndex = device.Renderings.Count - 1; renderingIndex >= 0; renderingIndex--)
                {
                    var rendering = device.Renderings[renderingIndex] as RenderingDefinition;

                    if (rendering == null)
                    {
                        continue;
                    }

                    // if the rendering has a custom data source, we resolve the data source item and place its text fields into the content to add
                    if (!string.IsNullOrWhiteSpace(rendering.Datasource))
                    {
                        //TODO:[Aza] - investigate on it - DataSourceHelper is a component of Blade
                        //var dataSource = DataSourceHelper.ResolveDataSource(rendering.Datasource, baseItem);

                        var dataSource = baseItem.Database.GetItem(rendering.Datasource);

                        if (dataSource != baseItem)
                        {
                            // Return the parent before its children
                            yield return dataSource;

                            if (dataSource.HasChildren) //TODO:[Aza] better logic check if datasource inherited from folder template 
                            {
                                foreach (Item item in dataSource.GetChildren())
                                {
                                    yield return item;
                                }
                            }
                        }
                    }
                }
            }

        }

        /// <summary>
        /// Extracts textual content from an item's fields
        /// </summary>
        protected virtual IEnumerable<string> GetItemContent(Item dataSource)
        {
            foreach (Field field in dataSource.Fields)
            {
                // this check is what Sitecore uses to determine if a field belongs in _content (see LuceneDocumentBuilder.AddField())
                if (!IndexOperationsHelper.IsTextField(new SitecoreItemDataField(field)))
                {
                    continue;
                }

               var fieldValue =(field.Value ?? string.Empty).StripTags();

                if (!string.IsNullOrWhiteSpace(fieldValue))
                {
                    yield return fieldValue;
                }
            }
        }

        
       
    }