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How to Create an Entity

In this document, you’ll learn how you can create a custom Entity.

Step 1: Create the Entity​

To create an entity, create a TypeScript file in src/models. For example, here’s a Post entity defined in the file src/models/post.ts:

src/models/post.ts
import { 
  BeforeInsert, 
  Column, 
  Entity, 
  PrimaryColumn,
} from "typeorm"
import { BaseEntity } from "@medusajs/medusa"
import { generateEntityId } from "@medusajs/medusa/dist/utils"

@Entity()
export class Post extends BaseEntity {
  @Column({ type: "varchar" })
  title: string | null

  @BeforeInsert()
  private beforeInsert(): void {
    this.id = generateEntityId(this.id, "post")
  }
}

This entity has one column title defined. However, since it extends BaseEntity it will also have the id, created_at, and updated_at columns.

Medusa’s core entities all have the following format for IDs: <PREFIX>_<RANDOM>. For example, an order might have the ID order_01G35WVGY4D1JCA4TPGVXPGCQM.

To generate an ID for your entity that matches the IDs generated for Medusa’s core entities, you should add a BeforeInsert event handler. Then, inside that handler use Medusa’s utility function generateEntityId to generate the ID. It accepts the ID as a first parameter and the prefix as a second parameter. The Post entity IDs will be of the format post_<RANDOM>.

If you want the entity to also be soft deletable then it should extend SoftDeletableEntity instead:

import { SoftDeletableEntity } from "@medusajs/medusa"

@Entity()
export class Post extends SoftDeletableEntity {
  // ...
}

You can learn more about what decorators and column types you can use in Typeorm’s documentation.

Step 2: Create a Migration​

Additionally, you must create a migration for your entity. Migrations are used to update the database schema with new tables or changes to existing tables.

You can learn more about Migrations, how to create or generate them, and how to run them in the Migration documentation.

Step 3: Create a Repository​

Entities data can be easily accessed and modified using Typeorm Repositories. To create a repository, create a file in src/repositories. For example, here’s a repository PostRepository created in src/repositories/post.ts:

src/repositories/post.ts
import { Post } from "../models/post"
import { 
  dataSource,
} from "@medusajs/medusa/dist/loaders/database"

export const PostRepository = dataSource
  .getRepository(Post)

export default PostRepository

The repository is created using the getRepository method of the data source exported from the core package in Medusa. This method accepts the entity as a parameter.

A data source is Typeorm’s connection settings that allows you to connect to your database. You can learn more about it in Typeorm’s documentation.

If you want to add methods to that repository or override Typeorm's Repository methods, you can do that using the extend method:

src/repositories/post.ts
import { Post } from "../models/post"
import { 
  dataSource,
} from "@medusajs/medusa/dist/loaders/database"

export const PostRepository = dataSource
  .getRepository(Post)
  .extend({
    customFunction(): void {
      // TODO add custom implementation
      return
    },
  })

export default PostRepository

You can learn about available Repository methods in Typeorm's documentation.

Step 4: Run Migrations​

Before you start using your entity, make sure to run the migrations that reflect the entity on your database schema.

To do that, run the build command that transpiles your code:

npm run build

Then, run the migration command:

medusa migrations run

You should see that your migration have executed.

Step 5: Use Your Entity​

You can access your custom entity data in the database in services or subscribers using the repository. For example, here’s a service that lists all posts:

import { TransactionBaseService } from "@medusajs/medusa"

class PostService extends TransactionBaseService {
  constructor({ postRepository, manager }) {
    super({ postRepository, manager })

    this.postRepository = postRepository
    this.manager_ = manager
  }

  async list() {
    const postRepo = this.manager_
      .withRepository(this.postRepository)
    return await postRepo.find()
  }
}

export default PostService

In the constructor, you can use dependency injection to get access to instances of services and repositories. Here, you initialize class fields postRepository and manager. The manager is a Typeorm Entity Manager.

Then, in the method list, you can create an instance of the PostRepository using the this.manager_.withRepository method passing it this.postRepository as a parameter.

After getting an instance of the repository, you can then use Typeorm’s Repository methods to perform Create, Read, Update, and Delete (CRUD) operations on your entity. You can also use any custom methods that you defined in the Repository.

This same usage of repositories can be done in other resources such as subscribers or endpoints.

Delete a Soft-Deletable Entity​

To delete soft-deletable entities that extend the SoftDeletableEntity class, you can use the repository method softDelete method:

await postRepository.softDelete(post.id)

See Also​