Entities
In this document, you'll learn what Entities are in Medusa.
What are Entities
Entities in medusa represent tables in the database as classes. An example of this would be the Order
entity which represents the order
table in the database. Entities provide a uniform way of defining and interacting with data retrieved from the database.
Aside from the entities in the Medusa core package, you can also create custom entities to use in your Medusa backend. Custom entities are TypeScript or JavaScript files located in the src/models
directory of your Medusa backend. You then transpile these entities to be used during the backend's runtime using the build
command, which moves them to the dist/models
directory.
Entities are based on Typeorm’s Entities and use Typeorm decorators. Each entity also require a repository to be created. A repository provides basic methods to access and manipulate the entity's data.
Base Entities
All entities must extend either the BaseEntity
or SoftDeletableEntity
classes. The BaseEntity
class holds common columns including the id
, created_at
, and updated_at
columns.
The SoftDeletableEntity
class extends the BaseEntity
class and adds another column deleted_at
. If an entity can be soft deleted, meaning that a row in it can appear to the user as deleted but still be available in the database, it should extend SoftDeletableEntity
.
metadata Attribute
Most entities in Medusa have a metadata
attribute. This attribute is an object that can be used to store custom data related to that entity. In the database, this attribute is stored as a JSON Binary (JSONB) column. On retrieval, the attribute is parsed into an object.
Some example use cases for the metadata
attribute include:
- Store an external ID of an entity related to a third-party integration.
- Store product customization such as personalization options.
Add and Update Metadata
You can add or update metadata entities either through the REST APIs or through create and update methods in the entity's respective service.
In the admin REST APIs, you'll find that in create or update requests of some entities you can also set the metadata
.
In services, there are typically create
or update
methods that allow you to set or update the metadata.
If you want to add a property to the metadata
object or update a property in the metadata
object, you can pass the metadata
object with the properties you want to add or update in it. For example:
If you want to remove a property from the metadata
object, you can pass the metadata
object with the property you want to delete. The property should have an empty string value. For example:
Custom Development
Developers can create custom entities in the Medusa backend, a plugin, or in a module, then ensure it reflects in the database using a migration.
Learn how to create an entity in Medusa.
Learn how to use a repository in Medusa.
Learn how to create migrations in Medusa.
Learn how to extend a core Medusa entity.
Learn how to extend a core Medusa repository.