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 your own entities to use in your Medusa backend. Custom entities are TypeScript or JavaScript files located in the src/models directory of your Medusa backend. These entities are then transpiled to the dist/models directory to be used during the backend's runtime.

Entities are TypeScript files and they are based on Typeorm’s Entities and use Typeorm decorators.

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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.

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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:

{
  // other data
  "metadata": {
    "is_b2b": true
  }
}

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:

{
  // other data
  "metadata": {
    "is_b2b": "" // this deletes the `is_b2b` property from `metadata`
  }
}

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What are Repositories

Repositories provide generic helper methods for entities. For example, a list method to retrieve all entities with pagination, or retrieve to retrieve a single entity record.

Repostories are Typeorm repositories, so you can refer to Typeorm's documentation on all available methods.

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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.

Create an Entity

Learn how to create an entity in Medusa.

Create a Migration

Learn how to create migrations in Medusa.

Extend an Entity

Learn how to extend a core Medusa entity.

Extend a Repository

Learn how to extend a core Medusa repository.