---
category: [Administration & Integrations, Administration & Integrations/Custom Integrations & Apps, Platform and Product Extensions, Platform and Product Extensions/Workday Extend, Platform and Product Extensions/Integration]
keyword: [Extend, Model Components]
nav: wcp_docs
parent_url: /wcp_docs/
title: >- 
  Concept: Update Model Components
layout: subsection
---

When you update an app with model components, you can:

-   Add new model components.
-   Add new fields to existing model components.
-   Add new security domains to business objects.
-   Add new security domains to individual fields on business objects.
-   Update page routes in business processes.


You can safely change the values in the `fields[]` section of a business object or attachment definition. This includes the ability to:

-   Change the `id` value of a field to a value that the model component has never used.
-   Change the `type` of a derived field.


However, you can't:

-   Change the `id` value of a model component. This `id` uniquely identifies your model components across all tenants.
-   Swap the `id` values between 2 fields of the same field type.
-   Change the `type` of a regular field.


Example: You can change the `label` of the Charity business object to Charitable Organization and then redeploy the app.

When you delete a model component from your app and then redeploy the app to a WCP Development tenant, Workday removes:

-   The deleted model component from the tenant.
-   All tenanted data associated with the deleted model component.


Example: You deploy the Charitable Donations app to your WCP Development tenant and create 1 or more Charity instances. If you delete the Charity business object from the app and then redeploy the app to the WCP Development tenant, Workday removes:

-   The Charity business object from the tenant.
-   The Charity instances that you created.


<b>Note:</b> After you promote an app, you can't:

-   Delete attachments, business objects, business processes, or regular fields.
-   Remove or change security domain assignments from attachment objects and business processes.


Workday recommends you develop your app as much as possible within a WCP Development tenant before you promote your app to an Implementation tenant. Example: Complete all unit testing in a Development tenant before you promote your app to an Implementation tenant for end-to-end testing.

### Related Information

[Reference: Allowed Updates After App Promotion](/wcp_docs/haf1635898070118.html)

[Tutorial: Extend Model Components Learning Program](https://wd5.myworkday.com/workday/learning/program/6a1b5a71c93c100094b72fead10f0000?type=2d29754fdb8e100008b50ff6bc94003b)

[Tutorial: Getting Started with Model Components](https://wd5.myworkday.com/workday/learning/course/84f2dcc34eff01f6facdbc20612cd98b?type=9882927d138b100019b928e75843018d)