---
title: Pass custom parameters to computed fields
slug: '2410'
canonical_url: https://docs.coveo.com/en/2410/
collection: coveo-for-sitecore-v5
source_format: adoc
---
# Pass custom parameters to computed fields
Sometimes, you may want to pass custom parameters to a computed field through the configuration.
For example, following the [Create a computed date field](https://docs.coveo.com/en/2237/) tutorial, you may want to control when the `archivedate` field is created on items.
This tutorial shows how to configure the number of days before an item is archived.

## Prerequisite

You have already completed the [Create a computed date field](https://docs.coveo.com/en/2237/) tutorial.

## Step 1: Update the Coveo.Custom project

. Using Visual Studio, [open the ArchiveDateField class](https://docs.coveo.com/en/2237#step-1-create-the-required-c-project).
. Add a constructor to accept additional XML configuration.

[source,c#]
```
 private readonly XmlNode m_Configuration;
 public ArchiveDateField(XmlNode p_Configuration)
 {
     m_Configuration = p_Configuration;
 }
```

. Add a method to parse the configuration XML attributes and return their value.

[source,c#]
```
 protected string GetConfigurationValue(string p_ConfigurationKey)
 {
     string configurationValue = null;
     if (m_Configuration != null && m_Configuration.Attributes != null) {
         XmlAttribute configurationAttribute = m_Configuration.Attributes[p_ConfigurationKey];
         if (configurationAttribute != null) {
             configurationValue = configurationAttribute.Value;
         }
     }
     return configurationValue;
 }
```

. Add a property to retrieve the configuration value formatted as an integer.

[source,c#]
```
 protected int DaysBeforeArchiving
 {
     get {
         int daysCount;
         if (!Int32.TryParse(GetConfigurationValue("daysBeforeArchiving"), out daysCount)) {
             daysCount = 365; // One year by default
         }
         return daysCount;
     }
 }
```

. Change the `ComputeFieldValue` method to use the `DaysBeforeArchiving` property.

[source,c#]
```
 /// <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);
             return itemCreationDate.AddDays(DaysBeforeArchiving).ToString(COVEO_INDEX_DATE_FORMAT);
         }
     }
     return null;
 }
```

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

## Step 2: Update the computed field configuration

Open your `Coveo.SearchProvider.Custom.config` file and add the `daysBeforeArchiving` parameter as an XML attribute.

```xml
 <field fieldName="archivedate" daysBeforeArchiving="30">Coveo.Custom.ArchiveDateField, Coveo.Custom</field>
```

## 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 values

Validate the `archivedate` field values 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/)).
There should now be a difference of 30 days between the `created` and `archivedate` fields values.

![Screenshot of the item in the Coveo Administration Console highlighting the archivedate and created field values | Coveo](https://docs.coveo.com/en/assets/images/c4sc-v5/35455016.png)

> **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.