---
title: Create a computed date field
slug: '2237'
canonical_url: https://docs.coveo.com/en/2237/
collection: coveo-for-sitecore-v5
source_format: adoc
---
# Create a computed date field
Suppose you want to create some kind of archiving system in Sitecore by adding a computed field.
For example, you would like to add an `archivedate` whose value would be one year after the item creation date (that is, `created` field in the example below).

![The Coveo Administration Console showing a difference of one year between the archivedate and created field values of an item](https://docs.coveo.com/en/assets/images/c4sc-v5/35455011.png)

This article provides the steps to achieve this.

> **Important**
>
> The [Coveo Platform](https://docs.coveo.com/en/186/) system date field and Coveo for Sitecore date field formats are incompatible.
> You can't use a mapping to populate a [Coveo Platform](https://docs.coveo.com/en/186/) system date field with a Coveo for Sitecore computed date field.

> **Note**
>
> If necessary, see [Implement and configure a computed field in your index](https://docs.coveo.com/en/2320/) for more details on each step.

## Step 1: Create the required C# project

. Create a new C# project named `Coveo.Custom` that references the `Sitecore.ContentSearch` and `Sitecore.Kernel` assemblies.

. Create a new class named `ArchiveDateField` in the `Coveo.Custom` namespace with the following code.

[source,c#]
```
using System;
using Sitecore;
using Sitecore.ContentSearch;
using Sitecore.ContentSearch.ComputedFields;

namespace Coveo.Custom
{
    public class ArchiveDateField : IComputedIndexField
    {
        // The 'Z' at the end of the format string tells Coveo
        // that the date value represents Universal time.
        private const string COVEO_INDEX_DATE_FORMAT = "yyyy/MM/dd@HH:mm:ssZ";
        private const string SITECORE_CREATED_FIELD = "__Created";
        /// <inheritdoc />
        public string FieldName { get; set; }
        /// <inheritdoc />
        public string ReturnType
        {
            get
            {
                return "datetime";
            }
            set
            {
            }
        }
        /// <inheritdoc />
        public object ComputeFieldValue(IIndexable p_Indexable)
        {
            SitecoreIndexableItem indexableItem = p_Indexable as SitecoreIndexableItem;
            if (indexableItem != null)
            {
                IIndexableDataField dateField = indexableItem.GetFieldByName(SITECORE_CREATED_FIELD);
                if (dateField != null)
                {
                    DateTime itemCreationDate = DateUtil.ParseDateTime(dateField.Value.ToString(), DateTime.MaxValue);
                    // Ensure that the date uses universal time
                    if (itemCreationDate.Kind != DateTimeKind.Utc)
                    {
                        itemCreationDate = itemCreationDate.ToUniversalTime();
                    }
                    return itemCreationDate.AddYears(1).ToString(COVEO_INDEX_DATE_FORMAT);
                }
            }
            return null;
        }
    }
}
```

> **Important**
>
> To create a computed date field, the `ReturnType` property must return the `datetime` string and the `ComputeFieldValue` method must return the date formatted as `yyyy/MM/dd@HH:mm:ssZ`.

. Compile your project.

. Copy the resulting assembly (`Coveo.Custom.dll`) to the `bin` folder of your Sitecore instance.

## Step 2: Configure the computed field

. In `Coveo.SearchProvider.Custom.config`, add the following element as a child of the `<fields hint="raw:AddComputedIndexField">` element.

```xml
<field fieldName="archivedate">Coveo.Custom.ArchiveDateField, Coveo.Custom</field>
```

. In `Coveo.SearchProvider.Custom.config`, add the following element as a child of the `<fieldNames hint="raw:AddFieldByFieldName>` element.

```xml
<fieldType fieldName="archivedate" settingType="Coveo.Framework.Configuration.FieldConfiguration, Coveo.Framework" returnType="System.DateTime" />
```

## Step 3: Rebuild your indexes

[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 4: 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/)).
Its value should be one year after the item creation date.

> **Warning**
>
> When running computed field code, check your logs for computed field errors indicating items aren't being indexed.
> Implement proper exception handling to avoid these issues.
> For example, you might want to stop the process or set a fallback value for a computed field when suitable.