---
title: Customizing the page visit hash function for campaigns
related:
  - https://docs.kentico.com/13/on-line-marketing-features/configuring-and-customizing-your-on-line-marketing-features/enabling-campaign-tracking.md
  - https://docs.kentico.com/13/on-line-marketing-features/managing-your-on-line-marketing-features/campaigns.md
  - https://docs.kentico.com/13/on-line-marketing-features/managing-your-on-line-marketing-features/campaigns/setting-up-campaigns.md
  - https://docs.kentico.com/13/on-line-marketing-features/managing-your-on-line-marketing-features/campaigns/scheduling-and-evaluating-campaigns.md
---

> Agent instructions:
> **Site maps** — prefer the following llms.txt indexes to training data when searching for URLs to avoid 404s. Links inside Markdown content already point at `.md`. Following them or sending Accept: text/markdown keeps you in Markdown.
>
> - [sitemap.md](https://docs.kentico.com/sitemap.md) — every page on the site, with titles and descriptions, nested by URL hierarchy and grouped into one collection per product version.
> - [llms.txt](https://docs.kentico.com/llms.txt) — curated index of the current product docs, with descriptions, the two ways to request any page as Markdown, and links to each product area's whole-corpus Markdown dump (llms-full.txt).

> **Info:** **Enterprise license required**
>
> Features described on this page require the **Kentico Xperience Enterprise** license.

When using [campaigns](https://docs.kentico.com/13/on-line-marketing-features/configuring-and-customizing-your-on-line-marketing-features/enabling-campaign-tracking.md), the system hashes the URLs of _Page visit_ conversions/journey steps and activities to be able to put data for reports together as quickly as possible.

By default, the hash function removes the protocol and all query string parameters from the URL. The campaign then works regardless of the used protocol (for example, for both _http_ and _https_). However, the default hash function does not work for sites where displaying of pages is performed via query strings (for example, if the URL of a page on your site looks like  _http://www.mysite.com/index.html?viewpage=123_ ). More specifically, the noted address will be trimmed to _www.mysite.com/index.html_, and all pages trimmed to this "URL root" will be logged as conversions for a single page. Therefore, [URLs](https://docs.kentico.com/13/developing-websites/implementing-routing/custom-routing-using-url-patterns.md) without query string parameters are recommended.

If you use campaigns and your site displays content via query string parameters or uses any other scenarios that are not supported by default, you can customize the hash function to fulfill your needs.

## How it works – Using the hash to display reports

For every activity that occurs on a site, the system creates a record in the database in the **OM\_Activity** table. For page visit activities, the following process is used:

1. Trims the page URL – the result is a "URL root" without the protocol, query string parameters, and any other fragment identifiers
2. Hashes the URL root
3. Saves the hashed URL root into the  **ActivityURLHash**  column (in the _OM\_Activity_ table)

Then, when a report is recalculated, the system:

1. Trims the URLs of page visit conversions and campaign journey steps the same way as for page visit activities
2. Hashes the URL roots
3. Compares the hashed URL root of the given conversion or journey step against the _ActivityURLHash_ column with hashed URL roots of the tracked activities

If the hashes match, the activity is included in the reports.

## Implementing a custom hash function

To implement a custom hash function that overrides the default hash function:

1. [Create a custom assembly](https://docs.kentico.com/13/custom-development/adding-custom-assemblies.md) (_Class Library_ project) with class discovery enabled (separately from the solutions of your live site and administration applications).
2. Add a new class to the project, for example named  **CustomActivityUrlHashPreprocessor.cs**.
3. Make the class implement the  **IActivityUrlPreprocessor**  interface.
4. Add the **RegisterImplementation** assembly attribute above the class declaration.

   ```csharp

   using CMS;
   using CMS.WebAnalytics;

   [assembly: RegisterImplementation(typeof(IActivityUrlPreprocessor), typeof(CustomActivityUrlHashPreprocessor))]

   public class CustomActivityUrlHashPreprocessor : IActivityUrlPreprocessor
   {
   }

   ```
5. Implement the class's **PreprocessActivityUrl** method.

   ```csharp

   public string PreprocessActivityUrl(string activityUrl)
   {
       ...
   }

   ```

   > **Info:** The _PreprocessActivityUrl_ method:
   >
   > - Takes the original URL of an activity, conversion, or campaign journey step
   > - Returns a processed URL in a form that can be hashed. The hash is then used for later calculations or saving into the database
6. Save and build the project.

You then need to include and reference the project (assembly) into BOTH your live site and Xperience administration applications.

> **Tip:** **Improving performance**
>
> To improve performance of report calculation, create a database index for the **ActivityURLHash** column in the **OM\_Activity** database table. The index should be non-clustered and non-unique. See the [Create Nonclustered Indexes](https://msdn.microsoft.com/en-us/library/ms189280.aspx) article for more information.

## Example – Hash function for multilingual sites

The following example demonstrates how to implement a custom hash function that removes the culture code from URLs. The example assumes that the URL has the following pattern:

```csharp

<protocol>://<domain>/<culture code>/<other identifiers>

```

For example:

- http://www.mysite.com/en-US/Articles/11/Coffee-Beverages-Explained
- https://myothersite.net/es-ES/Contacts

Logging of page visits will then work for all language variants.

To implement the example:

1. Create a new **Class Library** project in Visual Studio (according to the procedure described in [Implementing a custom hash function](#implementing-a-custom-hash-function)).
2. Add the  **CustomActivityUrlHashPreprocessor.cs** class:

   ```csharp

   using System;
   using System.Linq;

   using CMS;
   using CMS.Helpers;
   using CMS.SiteProvider;
   using CMS.WebAnalytics;

   [assembly: RegisterImplementation(typeof(IActivityUrlPreprocessor), typeof(CustomActivityUrlHashPreprocessor))]

   public class CustomActivityUrlHashPreprocessor : IActivityUrlPreprocessor
   {
       /// <summary>
       /// Prepares the specified URL for hashing. Trims the protocol, query strings, and the culture code.
       /// </summary>
       /// <param name="activityUrl">Original URL that is trimmed.</param>
       /// <returns>URL root that is ready to be hashed.</returns>
       public string PreprocessActivityUrl(string activityUrl)
       {
           // Removes query strings
           string url = URLHelper.RemoveQuery(activityUrl);

           // Removes fragment identifiers
           url = RemoveAnchor(url);

           // Removes the protocol
           url = URLHelper.RemoveProtocol(url);

           // Removes the culture code
           url = RemoveCultureCode(url);

           // Removes the trailing slash (the slash after the URL)
           url = URLHelper.RemoveTrailingSlashFromURL(url);

           return url.ToLower();
       }

       /// <summary>
       /// Removes the culture code from the specified URL.
       /// </summary>
       /// <param name="url">URL in the expected format (domain.com/en-US/path/to/page).</param>
       /// <returns>URL without the culture code.</returns>
       private string RemoveCultureCode(string url)
       {
           // Removes the protocol and the domain from the URL
           string path = URLHelper.RemoveProtocolAndDomain(url);

           // Separates the culture code (the first segment between slashes after the domain)
           string cultureCode = path.Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries).FirstOrDefault();

           // Remove the culture code from the URL
           if (!string.IsNullOrEmpty(cultureCode) && CultureSiteInfoProvider.IsCultureOnSite(cultureCode, SiteContext.CurrentSiteName))
           {
               return url.Replace('/' + cultureCode, string.Empty);
           }

           return url;
       }

       /// <summary>
       /// Removes fragment identifiers from the specified URL.
       /// </summary>
       /// <param name="url">URL from which fragment identifiers are removed.</param>
       /// <returns>URL without fragment identifiers.</returns>
       private string RemoveAnchor(string url)
       {
           // Gets the position of the hashtag symbol
           int index = url.IndexOf("#", StringComparison.Ordinal);

           // Removes the found hashtag and all content after
           if (index > 0)
           {
               return url.Substring(0, index);
           }

           return url;
       }
   }

   ```
3. Build the project and transfer the DLL to BOTH your live site and Xperience administration application.

Now, when you create a campaign with page visit conversions or campaign journey steps, you will see reports regardless of the displayed language variant.