7.2. Implement Value Accessor Converter

A converter is needed to convert a Sitecore item that represents a value accessor into a value accessor component for Data Exchange Framework.

1. In Visual Studio, add the following class:

   using Sitecore.Services.Core.Model;
   using System;
   
   namespace Examples.FileSystem.Models.ItemModels.DataAccess
   {
       public class ArrayValueAccessorItemModel : ItemModel
       {
           public const string Position = "Position";
       }
   }
   

   Note

   This class defines constants for the names of the fields from the value accessor template. These field names are referenced by the converter.

   In order for the converter to be able to run inside or outside of the Sitecore server, the type Sitecore.Services.Core.Model.ItemModel is used to represent Sitecore items. Fields on this type are accessed by name.

   This stands in contrast to how field are accessed on Sitecore.Data.Items.Item. In this type, fields can be accessed by name or ID, with ID being the preferred value since it is unlikely to change.

2. Add the following class:

   using Examples.FileSystem.Models.ItemModels.DataAccess;
   using Sitecore.DataExchange.Converters.DataAccess.ValueAccessors;
   using Sitecore.DataExchange.DataAccess;
   using Sitecore.DataExchange.DataAccess.Readers;
   using Sitecore.DataExchange.DataAccess.Writers;
   using Sitecore.DataExchange.Repositories;
   using Sitecore.Services.Core.Model;
   using System;
   
   namespace Examples.FileSystem.Converters.DataAccess.ValueAccessors
   {
       public class ArrayValueAccessorConverter : ValueAccessorConverter
       {
           private static readonly Guid TemplateId = Guid.Parse("[VALUE ACCESSOR TEMPLATE ID]");
           public ArrayValueAccessorConverter(IItemModelRepository repository) : base(repository)
           {
               this.SupportedTemplateIds.Add(TemplateId);
           }
           public override IValueAccessor Convert(ItemModel source)
           {
               var accessor = base.Convert(source);
               if (accessor == null)
               {
                   return null;
               }
               var position = base.GetIntValue(source, ArrayValueAccessorItemModel.Position);
               if (position <= 0)
               {
                   return null;
               }
               //
               //array position is 1-based in the Sitecore item but is 0-based in the reader/writer
               position--;
               //
               //unless a reader or writer is explicitly set use the property value
               if (accessor.ValueReader == null)
               {
                   accessor.ValueReader = new ArrayValueReader(position);
               }
               if (accessor.ValueWriter == null)
               {
                   accessor.ValueWriter = new ArrayValueWriter(position);
               }
               return accessor;
           }
   
       }
   }
   

   Important

   You must change the value of [VALUE ACCESSOR TEMPLATE ID] to match the id from the value accessor template you created named Array Value Accessor.

   Hint

   By inheriting from ValueAccessorConverter you get access to a number of methods that facilitate reading values from fields on a Sitecore item.

   In addition to being able to read simple values like strings, numbers and dates, methods are available to automatically convert referenced items into the appropriate Data Exchange Framework component.

   See the API documentation for more information.