c90191eb7e
* revamp create endpoint docs * docs: revamped endpoints, services, and entities * eslint fixes * fix metadata * fix missing closing tag * fixes to create migration doc * fixes to create endpoint doc * small fix in create service doc
145 lines
6.0 KiB
Markdown
145 lines
6.0 KiB
Markdown
---
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description: 'Learn how to create a migration in Medusa. This guide explains how to write and run migrations.'
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addHowToData: true
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---
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# How to Create Migrations
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In this document, you’ll learn how to create a [Migration](./overview.mdx) using [Typeorm](https://typeorm.io) in Medusa.
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## Step 1: Create Migration File
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There are two ways to create a migration file: create and write its content manually, or create and generate its content.
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If you're creating a custom entity, then it's recommended to generate the migration file. However, if you're extending an entity from Medusa's core, then you should create and write the migration manually.
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### Option 1: Generate Migration File
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:::warning
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Generating migration files for extended entities may cause unexpected errors. It's highly recommended to write them manually instead.
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:::
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Typeorm provides a `migration:generate` command that allows you to pass it a Typeorm [DataSource](https://typeorm.io/data-source). The `DataSource` includes database connection details, as well as the path to your custom entities.
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Start by creating the file `datasource.js` in the root of your Medusa backend project with the following content:
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```js
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const { DataSource } = require("typeorm")
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const AppDataSource = new DataSource({
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type: "postgres",
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port: 5432,
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username: "<YOUR_DB_USERNAME>",
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password: "<YOUR_DB_PASSWORD>",
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database: "<YOUR_DB_NAME>",
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entities: [
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"dist/models/*.js",
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],
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migrations: [
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"dist/migrations/*.js",
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],
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})
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module.exports = {
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datasource: AppDataSource,
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}
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```
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Make sure to replace `<YOUR_DB_USERNAME>`, `<YOUR_DB_PASSWORD>`, and `<YOUR_DB_NAME>` with the necessary values for your database connection.
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Then, after creating your entity, run the `build` command:
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```bash npm2yarn
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npm run build
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```
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Finally, run the following command to generate a migration for your custom entity:
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```bash
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npx typeorm migration:generate -d datasource.js src/migrations/PostCreate
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```
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This will generate the migration file in the path you specify, where `PostCreate` is just an example of the name of the migration to create. The migration file must be inside the `src/migrations` directory. When you run the build command, it will be transpiled into the `dist/migrations` directory.
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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](../../plugins/create.mdx).
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You can now continue to [step 2](#step-2-build-files) of this guide.
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### Option 2: Write Migration File
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With this option, you'll use Typeorm's CLI tool to create the migration file, but you'll write the content yourself.
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Run the following command in the root directory of your Medusa backend project:
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```bash
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npx typeorm migration:create src/migrations/PostCreate
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```
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This will create the migration file in the path you specify, where `PostCreate` is just an example of the name of the migration to create. The migration file must be inside the `src/migrations` directory. When you run the build command, it will be transpiled into the `dist/migrations` directory.
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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](../../plugins/create.mdx).
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If you open the file, you'll find `up` and `down` methods. The `up` method is used to reflect the changes on the database. The `down` method is used to revert the changes, which will be executed if the `npx medusa migrations revert` command is used.
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In each of the `up` and `down` methods, you can write the migration either with [SQL syntax](https://www.postgresql.org/docs/current/sql-syntax.html), or using the [migration API](https://typeorm.io/migrations#using-migration-api-to-write-migrations).
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For example:
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<!-- eslint-disable max-len -->
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```ts
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import { MigrationInterface, QueryRunner } from "typeorm"
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export class AddAuthorsAndPosts1690876698954 implements MigrationInterface {
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name = "AddAuthorsAndPosts1690876698954"
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public async up(queryRunner: QueryRunner): Promise<void> {
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await queryRunner.query(`CREATE TABLE "post" ("id" character varying NOT NULL, "created_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(), "updated_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(), "title" character varying NOT NULL, "author_id" character varying NOT NULL, "authorId" character varying, CONSTRAINT "PK_be5fda3aac270b134ff9c21cdee" PRIMARY KEY ("id"))`)
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await queryRunner.query(`CREATE TABLE "author" ("id" character varying NOT NULL, "created_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(), "updated_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(), "name" character varying NOT NULL, "image" character varying, CONSTRAINT "PK_5a0e79799d372fe56f2f3fa6871" PRIMARY KEY ("id"))`)
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await queryRunner.query(`ALTER TABLE "post" ADD CONSTRAINT "FK_c6fb082a3114f35d0cc27c518e0" FOREIGN KEY ("authorId") REFERENCES "author"("id") ON DELETE NO ACTION ON UPDATE NO ACTION`)
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}
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public async down(queryRunner: QueryRunner): Promise<void> {
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await queryRunner.query(`ALTER TABLE "post" DROP CONSTRAINT "FK_c6fb082a3114f35d0cc27c518e0"`)
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await queryRunner.query(`DROP TABLE "author"`)
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await queryRunner.query(`DROP TABLE "post"`)
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}
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}
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```
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:::warning
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If you're copying the code snippet above, make sure to not copy the class name or the `name` attribute in it. Your migration should keep its timestamp.
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:::
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---
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## Step 2: Build Files
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Before you can run the migrations, you need to run the build command to transpile the TypeScript files to JavaScript files:
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```bash npm2yarn
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npm run build
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```
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---
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## Step 4: Run Migration
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The last step is to run the migration with the command detailed earlier
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```bash
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npx medusa migrations run
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```
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If you check your database now you should see that the change defined by the migration has been applied successfully.
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---
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## See Also
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- [Create a Plugin](../../plugins/create.mdx)
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