Computed Fields in Sitecore

Greetings,

I will be providing a comprehensive overview of computed fields both in a general context and specifically in the context of the Sitecore platform. This discussion will encompass practical scenarios, illustrative examples from real-life requirements, and the accompanying code implementations.

Understanding Computed Fields

At its core, a computed field is a dynamic field that calculates its value based on the values of other fields, parameters, or custom logic. Unlike regular fields, computed fields do not store a specific value in the database. Instead, they generate their value on-the-fly when queried or displayed. This makes them extremely flexible, as their output can change in real-time based on changing conditions.

How Computed Fields Work in Sitecore 

Computed fields in Sitecore are created using .NET code, making use of Sitecore's API and libraries. Essentially, you define a custom logic that determines how the computed field's value should be calculated. This logic is executed whenever the computed field's value is requested. Computed fields can be used in various contexts, including content items, search indexes, and reports.

Creating Computed Fields in Sitecore

Creating computed fields in Sitecore involves defining a class that implements the Sitecore.ContentSearch.ComputedFields.IComputedIndexField interface. This class should contain the logic to calculate the field's value. You'll also need to configure the computed field in Sitecore's configuration files.

Imagine you're working with a Sitecore template that boasts two distinct fields: a Single Line Text field and a Multilist field. When you proceed to index this template and its corresponding items, the Solr index will create fields for each entry.

By navigating to the Solr admin, you can scrutinize these fields.

Notably, you can execute queries like _groupby : "ItemID" or _template:"TemplateID", ensuring that the lowercase format with hyphens and braces for ItemID or TemplateID is maintained. This method effectively unveils these fields within the Solr index.

However, a challenge emerges when dealing with the Multilist field. Currently, the Solr index showcases the Item IDs of the selected items within this field. The desire, however, is to retrieve the title field of the selected item within the Multilist, as opposed to its Item ID.

In order to surmount this obstacle, Sitecore offers a solution in the form of computed fields. By utilizing these fields, it's feasible to manipulate the information within the Solr index to align with specific requirements. This functionality empowers the extraction of the desired title field from the Multilist, effectively enhancing the precision and relevance of search results..

1.Create a Computed Field Class:

Create a class that inherits from Sitecore.ContentSearch.ComputedFields.IComputedIndexField. This class will calculate the values for the computed field.

using Sitecore.ContentSearch;
using Sitecore.ContentSearch.ComputedFields;
using Sitecore.Data.Fields;
using Sitecore.Data.Items;
public class MultilistNamesComputedField : IComputedIndexField
{
public string FieldName { get; set; }
public string ReturnType { get; set; }
public object ComputeFieldValue(IIndexable indexable)
{
Item item = indexable as SitecoreIndexableItem;
MultilistField multilistField = item.Fields[FieldName];
if (multilistField == null)
{
return null;
}
var names = new List<string>();
foreach (var targetID in multilistField.TargetIDs)
{
Item targetItem = item.Database.GetItem(targetID);
if (targetItem != null)
{
names.Add(targetItem["Title"]); // Assuming the name field is "Title"
}
}
return names;
}
}

2.Configure the Computed Field:

 In your Solr indexing configuration, define the computed field in your Sitecore.ContentSearch.Solr.IndexConfiguration.config or equivalent configuration file:

<fieldMap>

    <fieldNames hint="raw:AddFieldByFieldName">

        <!-- ... other field mappings ... -->

        <field fieldName="multilistnames" returnType="stringCollection">YourNamespace.MultilistNamesComputedField, YourAssembly</field>

    </fieldNames>

</fieldMap>

Use the Computed Field in Search:

After indexing, you can use the computed field in your search queries. In a Solr search query, you can include the multilistnames field to retrieve the concatenated names of the items in the multilist.

Your field will appear as multilistnames.

Happy coding!