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How to Create Migrations

In this document, you’ll learn how to create a Migration using Typeorm in Medusa.

Step 1: Create Migration File​

To create a migration that makes changes to your Medusa schema, run the following command:

npx typeorm migration:create src/migrations/UserChanged

This will create the migration file in the path you specify. You can use this without the need to install Typeorm's CLI tool. You can then go ahead and make changes to it as necessary.

The migration file must be inside the src/migrations directory. When you run the build command, it will be transpiled into the directory dist/migrations. The migrations run command can only pick up migrations under the dist/migrations directory on a Medusa backend. This applies to migrations created in a Medusa backend, and not in a Medusa plugin. For plugins, check out the Plugin's Structure section.

Generating Migrations for Entities

You can alternatively use Typeorm's generate command to generate a Migration file from existing entity classes. As of v1.8, Medusa uses Typeorm v0.3.x. You have to create a DataSource first before using the migration:generate command.

For example, create the file datasource.js in the root of your Medusa server with the following content:

const { DataSource } = require("typeorm")

const AppDataSource = new DataSource({
  type: "postgres",
  port: 5432,
  username: "<YOUR_DB_USERNAME>",
  password: "<YOUR_DB_PASSWORD>",
  database: "<YOUR_DB_NAME>",
  entities: [
    "dist/models/*.js",
  ],
  migrations: [
    "dist/migrations/*.js",
  ],
})

module.exports = {
  datasource: AppDataSource,
}

Make sure to replace <YOUR_DB_USERNAME>, <YOUR_DB_PASSWORD>, and <YOUR_DB_NAME> with the necessary values for your database connection.

Then, after creating your entity, run the build command:

npm run build

Finally, run the following command to generate a Migration for your new entity:

npx typeorm migration:generate -d datasource.js src/migrations/PostCreate

Where PostCreate is just an example of the name of the migration to generate. The migration will then be generated in src/migrations/<TIMESTAMP>-PostCreate.ts. You can then skip to step 3 of this guide.

Step 2: Write Migration File​

The migration file contains the necessary commands to create the database columns, foreign keys, and more.

You can learn more about writing the migration file in You can learn more about writing migrations in Typeorm’s Documentation.

Step 3: Build Files​

Before you can run the migrations you need to run the build command to transpile the TypeScript files to JavaScript files:

npm run build

Step 4: Run Migration​

The last step is to run the migration with the command detailed earlier

medusa migrations run

If you check your database now you should see that the change defined by the migration has been applied successfully.

See Also​