---
title: Create a computed field for a referenced item
slug: '2238'
canonical_url: https://docs.coveo.com/en/2238/
collection: coveo-for-sitecore-v5
source_format: adoc
---
# Create a computed field for a referenced item
A Sitecore field can reference another Sitecore item, which contains several fields of its own.
Sometimes, you may need to retrieve a field from the referenced item to use it in a computed field.

![Logic behind Coveo for Sitecore out-of-the-box computed fields | Coveo for Sitecore 5](https://docs.coveo.com/en/assets/images/c4sc-v5/out-of-the-box-computed-fields.png)

This can be done using the [`referencedfieldcomputedfield`](https://docs.coveo.com/en/2623#the-referencedfieldcomputedfield-computed-field) computed field.

This article provides an example showing how to use the out-of-the-box `ReferencedFieldComputedField` computed field.

## Scenario

Your content tree contains items of type _Flight_ and items of type _Airport_.

A _Flight_ contains the following fields:

|===
| Field name | Field type | Example value

| Flight Number
| Single-Line Text
| 3836

| Departure Airport
| Droptree (reference)
| Airports/2/3/8/2/0/Amsterdam Airport Schiphol (raw value is actually \{23820EE7-87A3-4265-B785-2A1D25C98F72}).

| Departure Time
| Datetime
| 5/23/2014 10:01 PM

| Arrival Airport
| Droptree (reference)
| Airports/9/C/2/F/4/Los Angeles International Airport (raw value is actually \{9C2F4988-0951-443C-9526-5DBB5D8D9C02}).

| Arrival Time
| Datetime
| 5/24/2014 12:16 AM

| Price
| Single-Line Text
| 586
|===

An _Airport_ contains the following fields:

|===
| Field name | Field type | Example value

| Airport Name
| Single-Line Text
| Amsterdam Airport Schiphol

| Airport Code
| Single-Line Text
| AMS

| City
| Single-Line Text
| Amsterdam

| State
| Single-Line Text
|

| Country
| Single-Line Text
| Netherlands

| Time Zone
| Droplink
| (+1:00) Central Europe Standard Time

| Latitude
| Number
| 52

| Longitude
| Number
| 5

| Aliases
| Single-Line Text
|
|===

Your goal is to populate a `departureairportcity` field in _Flight_ items by retrieving the content of the `City` field from a referenced _Airport_ item.
In other words, you want to do this:

![Logic behind ReferencedFieldComputedField in flight and airport example | Coveo for Sitecore 5](https://docs.coveo.com/en/assets/images/c4sc-v5/out-of-the-box-referenced-field.png)

## Step 1: Configure the computed field

Configure your computed field in the Coveo Search Provider configuration file.

. Using a text editor, open the `Coveo.SearchProvider.Custom.config` file (typically located under `App_Config\Include\Coveo`).
. Locate the `fields` element with a `hint` attribute equal to `raw:AddComputedIndexField`.
. Insert the configuration required for your computed field as shown below (that is, just the inner `field` element).

```xml
 <fields hint="raw:AddComputedIndexField">
   <field fieldName="departureairportcity" sourceField="Departure Airport" referencedFieldName="City">Coveo.SearchProvider.ComputedFields.ReferencedFieldComputedField, Coveo.SearchProviderBase</field>
 </fields>
```

Here are the available options for your computed field configuration:


<div class="table-wrap" style="display: block;" >
<table>
<colgroup>
<col style="width: 33%" />
<col style="width: 33%" />
<col style="width: 33%" />
</colgroup>
<thead>
<tr>
<th>Name</th>
<th>Description</th>
<th>Example value</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>fieldName</code></td>
<td>The name of the new field to create</td>
<td><code>departureairportcity</code></td>
</tr>
<tr>
<td><code>sourceField</code></td>
<td>The field containing the referenced item's ID</td>
<td>Departure Airport</td>
</tr>
<tr>
<td><code>referencedFieldName</code></td>
<td>The name of the field on the referenced item</td>
<td>City</td>
</tr>
<tr>
<td><code>returnType</code></td>
<td>Return type of the field</td>
<td>The possible values are: <code>Integer</code>, <code>Number</code>, <code>date</code>, <code>datetime</code>, and <code>string</code>.</td>
</tr>
</tbody>
</table>
</div>


> **Note**
>
> This configuration lets you create and index the computed field.
> To apply special settings to that field (for example, to use it as a facet or to sort results), you also need to [add a configuration in the `fieldNames` section](https://docs.coveo.com/en/2166/) of the configuration file.

## Step 2: Rebuild your indexes

> **Important**
>
> To have the computed field created, the related `sourceField` and `referencedFieldName` fields must be in [the `<include>` fields list](https://docs.coveo.com/en/2566#fields).

To be able to use your newly created computed field, you now need to perform an indexing action.
[Rebuild your search indexes](https://docs.coveo.com/en/2426#rebuilding-a-search-index-manually), or at least [re-index the Sitecore items which need the new field](https://docs.coveo.com/en/2426#re-indexing-a-section-of-your-content-tree-in-the-content-editor).

## Step 3: Validate the computed field has been added

Validate that your new field has been added on your items using the [**Content Browser**](https://platform.cloud.coveo.com/admin/#/orgid/content/browser/) ([platform-ca](https://platform-ca.cloud.coveo.com/admin/#/orgid/content/browser/) | [platform-eu](https://platform-eu.cloud.coveo.com/admin/#/orgid/content/browser/) | [platform-au](https://platform-au.cloud.coveo.com/admin/#/orgid/content/browser/)).

In this example, Flight items should now have a field named `departureairportcity` that contains the city of the departure airport.

![Flight departure airport city computed field value in Content Browser | Coveo for Sitecore 5](https://docs.coveo.com/en/assets/images/c4sc-v5/out-of-the-box-referenced-field-result.png)

## Step 4: Use the computed field

You can now use your computed field in your layouts and [result templates](https://docs.coveo.com/en/2834/).