How to Extend a Service
In this document, you’ll learn how to extend a core service in Medusa.
Medusa’s core services cover a wide range of functionalities related to each domain or entity. You can extend these services to add custom methods or override existing methods.
Word of Caution about Overriding
Extending services to add new methods shouldn't cause any issues within your commerce application. However, if you extend them to override their existing methods, you should be aware that this could have negative implications, such as unanticipated bugs, especially when you try to upgrade the core Medusa package to a newer version.
Step 1: Create the Service File
In your Medusa backend, create the file
src/services/product.ts. This file will hold your extended service.
Note that the name of the file must be the same as the name of the original service in the core package. So, if you’re extending the
ProductService, the file’s name should be
product.ts. On the other hand, if you’re extending the
CustomerService, the file’s name should be
Step 2: Implementing the Service
In the file, you can import the original service from the Medusa core, then create your service that extends the core service.
For example, to extend the Product service:
Notice that you alias the
ProductService of the core to avoid naming conflicts.
Within the service, you can add new methods or extend existing ones.
You can also change the lifetime of the service:
You can learn more details about the service lifetime and other considerations when creating a service in the Create Service documentation.
Step 3: Test it Out
To test out your customization, start by transpiling your files by running the following command in the root directory of the Medusa backend:
Then, start the backend:
You should see the customizations you made in effect.