Shahed Nasser
0462cc5acf
- Change existing data model guides and add new ones for DML - Change module's docs around service factory + remove guides that are now necessary - Hide/remove all mentions of module relationships, or label them as coming soon. - Change all data model creation snippets to use DML - use `property` instead of `field` when referring to a data model's properties. - Fix all snippets in commerce module guides to use new method suffix (no more main model methods) - Rework recipes, removing/hiding a lot of sections as a lot of recipes are incomplete with the current state of DML. ### Other changes - Highlight fixes in some guides - Remove feature flags guide - Fix code block styles when there are no line numbers. ### Upcoming changes in other PRs - Re-generate commerce module references (for the updates in the method names) - Ensure that the data model references are generated correctly for models using DML. - (probably at a very later point) revisit recipes
144 lines
4.3 KiB
Plaintext
144 lines
4.3 KiB
Plaintext
export const metadata = {
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title: `${pageNumber} Data Models`,
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}
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# {metadata.title}
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In this chapter, you’ll learn what data models are and how to create a data model.
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## What is a Data Model?
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A data model is a class that represents a table in the database. It's created in a module.
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---
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## How to Create a Data Model
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<Note title="Steps Summary">
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1. Create data model class in a module.
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2. Generate migration for the data model.
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4. Run migration to add table for data model in the database.
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</Note>
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A data model is created in a TypeScript or JavaScript file under a module's `models` directory. It's defined using the `model` utility imported from `@medjusajs/utils`.
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For example, create the file `src/modules/hello/models/my-custom.ts` with the following content:
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```ts title="src/modules/hello/models/my-custom.ts"
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import { model } from "@medusajs/utils"
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const MyCustom = model.define("my_custom", {
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id: model.id(),
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name: model.text(),
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})
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export default MyCustom
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```
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You define a data model using the `model`'s `define` method. It accepts two parameters:
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1. The first one is the name of the data model's table in the database.
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2. The second is an object, which is the data model's schema. The schema's properties are defined using the `model`'s methods.
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The example above defines the data model `MyCustom` with the properties `id` and `name`.
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### Create a Migration
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A migration defines changes to be made in the database, such as create or update tables.
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So, you must create a migration that creates a table for your data model in the database.
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A migration is a class created in a TypeScript or JavaScript file under a module's `migrations` directory. It has two methods:
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- The `up` method reflects changes on the database.
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- The `down` method reverts the changes made in the `up` method.
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<Details summaryContent="Generate Migration">
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To generate migrations:
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1. Create the file `src/modules/hello/migrations-config.ts` with the following content:
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```ts highlights={[["7", '"medusa-hello"', "Use any database name relevant for your module."]]}
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import { defineMikroOrmCliConfig } from "@medusajs/utils"
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import path from "path"
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import MyCustom from "./models/my-custom"
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export default defineMikroOrmCliConfig({
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entities: [MyCustom] as any[],
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databaseName: "medusa-hello",
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migrations: {
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path: path.join(__dirname, "migrations"),
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},
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})
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```
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2. Run the following command in the root directory of your Medusa application:
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```bash
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npx cross-env MIKRO_ORM_CLI=./src/modules/hello/migrations-config.ts mikro-orm migration:create
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```
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<Note title="Tip">
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Add this command as a script in `package.json` for easy usage in the future. Use this command whenever you want to generate a new migration in your module.
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</Note>
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After running the command, a migration file is generated under the `src/modules/hello/migrations` directory.
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</Details>
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For example:
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```ts title="src/modules/migrations/Migration20240429090012.ts"
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import { Migration } from "@mikro-orm/migrations"
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export class Migration20240624145652 extends Migration {
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async up(): Promise<void> {
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this.addSql("create table if not exists \"my_custom\" (\"id\" text not null, \"name\" text not null, \"created_at\" timestamptz not null default now(), \"updated_at\" timestamptz not null default now(), \"deleted_at\" timestamptz null, constraint \"my_custom_pkey\" primary key (\"id\"));")
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}
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async down(): Promise<void> {
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this.addSql("drop table if exists \"my_custom\" cascade;")
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}
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}
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```
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In the `up` method, you create the table `my_custom` and define its columns. In the `down` method, you drop the table.
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<Note title="Tip">
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The queries performed in each of the methods use PostgreSQL syntax.
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</Note>
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### Run Migration
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To reflect the changes in the migration, run the `migration` command:
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```bash npm2yarn
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npx medusa migrations run
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```
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If ran successfully, the `my_custom` table will be created in the database.
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---
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## When to Use Data Models
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<Note title="Use data models when" type="success">
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- You want to store data related to your customization in the database.
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</Note>
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<Note title="Don't use data models if" type="error">
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- You want to store simple key-value pairs related to an existing data model. Instead, use the `metadata` field that most existing models have, which is an object of custom key-value pairs.
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</Note>
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