---
title: Map custom member fields to contacts
related:
  - https://docs.kentico.com/documentation/developers-and-admins/development/registration-and-authentication/add-fields-to-member-objects.md
  - https://docs.kentico.com/documentation/developers-and-admins/digital-marketing-setup/contact-configuration.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).

When a visitor [registers](https://docs.kentico.com/documentation/developers-and-admins/development/registration-and-authentication.md) as a [member](https://docs.kentico.com/documentation/business-users/members.md), the system logs the _Member registration_ [activity](https://docs.kentico.com/documentation/business-users/digital-marketing/contact-activities.md). The activity is logged for a [contact](https://docs.kentico.com/documentation/business-users/digital-marketing/contact-management.md), not directly for the registered member.

As part of this process, the system maps the member data submitted during registration to the corresponding contact. By default, the member **email address** is mapped (for contacts with an empty value in their email field).  In their initial state, members contain a basic set of fields required for simple authentication scenarios, and only the email address is relevant for contacts.

If you have [added custom fields to the member object](https://docs.kentico.com/documentation/developers-and-admins/development/registration-and-authentication/add-fields-to-member-objects.md), for example a first and last name, you can extend the member-contact mapping behavior by creating and registering an `IMemberToContactMapper` implementation.

## Implement the custom member field mapper

We recommend extending the default implementation of the `IMemberToContactMapper` service using the [decorator customization pattern](https://docs.kentico.com/documentation/developers-and-admins/customization/decorate-system-services.md#decorate-services-via-dependency-injection). First map your custom member fields to the contact (without setting the `ContactInfo` object), and then call the default implementation to map the email address and save the contact details.

Start by preparing a separate project for custom classes in your Xperience solution:

1. Open your solution in Visual Studio.
2. [Add a custom assembly](https://docs.kentico.com/documentation/developers-and-admins/customization/integrate-custom-code.md) (_Class Library_ project) with class discovery enabled to the solution, or re-use an existing assembly.
3. Reference the project from your Xperience website project.

Continue by implementing the custom class:

1. Create a new custom class. For example, name the class `CustomMemberToContactMapper`.
2. Make the class implement the `IMemberToContactMapper` interface.
3. Add the `Map` method:

   - Get any required data from the `MemberInfo` parameter, and set the values into the `ContactInfo` parameter.
   - Use the [decorator customization pattern](https://docs.kentico.com/documentation/developers-and-admins/customization/decorate-system-services.md#decorate-services-via-dependency-injection) to call the default implementation of the `Map` method. This ensures mapping of the member email address (if the contact's email is empty), and then saves the `ContactInfo` object.

   > **Note:** The default implementation does not save any changes made to the `MemberInfo` object.
4. Register the implementation using the `RegisterImplementation` assembly attribute.

### Example

The following code example demonstrates how to implement contact mapping of custom _FirstName_ and _LastName_ member fields.

```csharp title="Mapping custom member fields to contact fields"
using CMS;
using CMS.ContactManagement;
using CMS.Membership;

using Kentico.OnlineMarketing.Web.Mvc;

[assembly: RegisterImplementation(typeof(IMemberToContactMapper), typeof(CustomMemberToContactMapper))]

public class CustomMemberToContactMapper : IMemberToContactMapper
{
    // Stores the default implementation of the IMemberToContactMapper service
    private readonly IMemberToContactMapper memberToContactMapper;

    public CustomMemberToContactMapper(IMemberToContactMapper memberToContactMapper)
    {
        this.memberToContactMapper = memberToContactMapper;
    }

    /// Maps the member's first and last name to the contact
    public void Map(MemberInfo member, ContactInfo contact)
    {
        // Gets the values from the member and sets them into the corresponding contact fields
        contact.ContactFirstName = member.GetValue<string>("FirstName", null);
        contact.ContactLastName = member.GetValue<string>("LastName", null);

        /* Calls the default IMemberToContactMapper.Map implementation
           This ensures mapping of the member email address (if the contact's email is empty) and saves the `ContactInfo` object
           If you choose not to call the default implementation, you need to manually:
            - Map the MemberEmail field to the ContactEmail field 
              We only recommend updating the contact email if the value is empty. Do not overwrite existing email address values.
            - Save the contact object (using the IInfoProvider<ContactInfo>.Set method)
        */
        memberToContactMapper.Map(member, contact);
    }
}
```

Now when a visitor submits your registration form, the values of the custom first name and last name member fields are automatically mapped to the contact for which the _Member registration_ activity is logged.