Examine

The search engine used within Umbraco

• https://shazwazza.github.io/Examine/

Add custom field to the Index

IndexerComponent : IComponent

Public void Initialize()
{
   externalIndex.FieldDefinitionCollection.AddOrUpdate(new FieldDefinition("FieldName", "FieldDataOrContent"));
}

Add content to custom field

In the same file - IndexerComponent.cs

   private void IndexResourceSpecificProperties(IndexingItemEventArgs e, ResourceItem resourceItem)
        {
            try
            {
                var resourceDate = resourceItem.ResourceDate;
                e.ValueSet.Add(Constants.Resources.ResourceDateSortableExamineField, resourceDate.Ticks);