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## Resource: About Data Extension Schemas

## Article: About Data Extension Schemas

## Article Link: https://dev.wix.com/docs/develop-websites-sdk/code-your-site/extend-wix-business-solutions/data-extension-schemas/about-data-extension-schemas.md

## Article Content:

# About Data Extension Schemas

Every Wix API has a Wix object with predefined fields. Depending on your use case, you might want to add custom fields to an object. [Data extension schemas](https://dev.wix.com/docs/api-reference/business-management/data-extension-schema/introduction.md) let you define the structure of custom fields and add them to Wix objects for a specific site. 

For example, if you run a furniture store, you might offer extended warranties. Using a data extension schema, you can define and add a `warranty` field to the [product](https://dev.wix.com/docs/api-reference/business-solutions/stores/catalog-v3/products-v3/introduction.md) object.

## Supported IDEs

You can work with data extension schemas in:

+ The editor (Wix Studio and Wix Editor)
+ The Wix IDE (Wix Studio)
+ Your local IDE (Wix Studio and Wix Editor)

## Supported objects

You can only extend objects that support data extension schemas. For the list of supported objects, see the [Data Extension Schema API](https://dev.wix.com/docs/api-reference/business-management/data-extension-schema/introduction.md).

## How extended fields work

Supported objects contain an `extendedFields` property. When you create a data extension schema, you define extended fields that are stored in `extendedFields`. Extended fields can exist at the following levels:

* **Root level:** Extended fields appear directly in the object's `extendedFields` property.
* **Nested in an existing field:** Extended fields appear in the `extendedFields` property of items in an array. For example, each line item in an order has its own `extendedFields` property.

## Data extension schema management  

You can manage extended fields for a site in the following ways:

* **Data Extension Schema API:** [define and manage](https://dev.wix.com/docs/api-reference/business-management/data-extension-schema/introduction.md) the schema of extended fields.
* **Site dashboard:** create and manage extended fields through the site dashboard. For example, Wix users can add extended fields to the checkout flow under **Settings** > **Checkout** > **Checkout form**.

Schemas added using these methods are stored in the `_user_fields` [namespace](https://dev.wix.com/docs/api-reference/business-management/data-extension-schema/introduction/.md#namespaces).

## Extended fields structure

The structure of extended fields is defined using a subset of [JSON Schema](https://dev.wix.com/docs/api-reference/business-management/data-extension-schema/the-json-schema.md). This schema acts as a blueprint that defines the data types and constraints for your extended fields. 

## Use cases

The following are possible use cases for data extension schemas: 

**Root-level extensions**
* Add accessories, such as sports equipment, in the [Booking](https://dev.wix.com/docs/rest/business-solutions/bookings/bookings/bookings-writer-v2/booking-object.md) object.
* Add a warranty field to the eCommerce [Order](https://dev.wix.com/docs/api-reference/business-solutions/e-commerce/orders/orders/order-object.md) object.
* Add a field to the [Checkout](https://dev.wix.com/docs/api-reference/business-solutions/e-commerce/purchase-flow/checkout/checkout/checkout-object.md) object giving users the option to send products as a gift.

**Nested field extensions**
* Add customization options (color, size, personalization) to individual line items in an [Order](https://dev.wix.com/docs/api-reference/business-solutions/e-commerce/orders/orders/order-object.md).
* Include rental duration or condition tracking for each line item in a [Booking](https://dev.wix.com/docs/rest/business-solutions/bookings/bookings/bookings-writer-v2/booking-object.md)'s equipment list at [Checkout](https://dev.wix.com/docs/api-reference/business-solutions/e-commerce/purchase-flow/checkout/checkout/checkout-object.md).
* Add delivery preferences or special handling instructions to specific line items at [Checkout](https://dev.wix.com/docs/api-reference/business-solutions/e-commerce/purchase-flow/checkout/checkout/checkout-object.md).


## See also

* [Data Extension Schema API](https://dev.wix.com/docs/api-reference/business-management/data-extension-schema/introduction.md)
* [JSON Schema reference](https://dev.wix.com/docs/develop-websites-sdk/code-your-site/extend-wix-business-solutions/data-extension-schemas/the-json-schema.md)
* [Extend an object with custom fields](https://dev.wix.com/docs/develop-websites-sdk/code-your-site/extend-wix-business-solutions/data-extension-schemas/extend-an-object-with-custom-fields.md)
* [Sample flows](https://dev.wix.com/docs/api-reference/business-management/data-extension-schema/sample-flows.md)
* [FAQ](https://dev.wix.com/docs/build-apps/develop-your-app/extensions/backend-extensions/schema-plugins/schema-plugin-faq.md)