Extensibility overview

AL developers can extend the functionality of Business Central in several ways. They can extend tables, enumerations, application areas, pages, reports, code flows, and the security model. They can also request missing extensibility points or contribute application changes through the open-source BCApps repository.

This article provides an overview of the extensibility options available to AL developers in Business Central including examples on how to extend various features, such as extending item charges, best price calculations, and data archiving.

Extending AL objects and artifacts

The AL object model in Business Central supports many different ways for developers to extend objects and artifacts in an app.

Extending the Business Central application

The Business Central application consists of multiple layers:

• The System Application, which is a set of open-source modules that make it easier to build, maintain, and upgrade on-premises and online apps. These modules let you focus on the business logic and the needs of your users or customers.
• The Base Application, which is the business logic for the functionality in Business Central.

Contributing to Business Central applications

The BCApps repository includes the Base Application, Business Foundation, System Application, Microsoft's first-party apps, and developer tools. If you want to contribute code, determine the type of contribution:

1. Small bug fixes, product improvements, or customer conveniences; or
2. New capabilities or larger changes to the existing application platform.

Before opening a pull request (PR), Microsoft must approve the related GitHub issue. Learn more in Contribute a change yourself and the BCApps contribution guidelines.

If you need a missing event, public procedure, or another extensibility point, create an extensibility request.

Learn more about the System Application, its module architecture, and how to modify or create new modules in Creating new modules in the system application.

Extending the Business Central base application

For more information on how to get started on extending functionality in the base application by extending AL objects and using events, see:

• Application reference for Dynamics 365 Business Central
• The Microsoft_Application.app file
• Publishing a code-customized base application
• Extending application areas

Extension objects in the same app

From runtime 13.0 and onwards, large applications have the ability to maintain a separation of concerns. This is achieved by permitting extension objects to coexist with their target within the same app. This facilitates the development of multiple extensions for a single target, all within the same app.

When table extensions live in the same app as their target, their fields and keys are integrated into the base table. This integration eliminates the need for SQL-joins during runtime.

All types of extension objects; enums, pages, reports, tables, and XMLports, can coexist with their target within the same app. This allows for various combinations, such as a single table with its table extension, a single page with multiple page extensions, multiple enum extensions, and so forth. This flexibility supports a wide range of application structures and functionalities.

Permitting extension objects to coexist with their target within the same app is useful for nondisruptive code refactoring within an app. It allows for dividing objects into modules based on specific functionalities, or for preparing to move objects into a separate app in anticipation of future releases.

With runtime 13.0, extension objects from a specific app are applied to the target based on the extension object ID. This introduces the following new compiler validations:

• Base objects are prohibited from referencing members from extension objects.
• An extension object can only reference members from other extension objects within the same app if the other extension object has a lower object ID.

Examples

Numerous examples demonstrate how to extend various features in Business Central:

• Extending item charges
• Extending best price calculations
• Extending pages based on date virtual table
• Data archive extension
• Extending document sharing with OneDrive
• Extending templates
• Extending email

These resources provide a comprehensive overview of the extensibility options available to AL developers in Business Central.

• Extending item charge distribution methods
• Extending price calculations
• Extending pages previously based on the Date virtual table
• Extending data archiving
• Extending document sharing and OneDrive integration
• Extending customer, vendor, and item templates
• Extending email capabilities
• Extending G/L entry aggregations when posting invoices
• Extending the Shopify Connector

Related information

Extending AL objects and artifacts

• Extending application areas
• Extending enumerations
• Extending AL code flows: events
• Extending pages
• Extending reports
• Extending the security model
• Extending tables

Extending the base application

• Contribute a change yourself
• Create an extensibility request
• BCApps contribution guidelines
• Application reference for Dynamics 365 Business Central
• The Microsoft_Application.app file
• Publishing a code-customized base application

Examples

• Example: extending item charge distribution methods
• Example: extending price calculations
• Example: extending pages previously based on the Date virtual table
• Example: extending data archiving
• Example: extending document sharing and OneDrive integration
• Example: extending customer, vendor, and item templates
• Example: extending email capabilities
• Example: extending G/L entry aggregations when posting invoices
• Example: extending the Shopify Connector