103 lines
2.4 KiB
Plaintext
103 lines
2.4 KiB
Plaintext
export const metadata = {
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title: `${pageNumber} Common Data Model Definitions`,
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}
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# {metadata.title}
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In this chapter, you'll learn where to find resources on common data model definitions related to field's column types, relations, and indices.
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## MikroORM Learning Resources
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Refer to the following resources to learn about common definitions:
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1. [Field column types](https://mikro-orm.io/docs/defining-entities).
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2. [Creating indices](https://mikro-orm.io/docs/defining-entities#indexes).
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Refer to MikroORM's documentation for more details related to your use case.
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---
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## Relations Between Data Models
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You can build relations between data models in the same module.
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Refer to [MikroORM's relations definition](https://mikro-orm.io/docs/relationships)
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<Note>
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For building relationships between data models in different module, refer to the [Module Relationships chapter](../../modules/module-relationships/page.mdx) instead.
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</Note>
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---
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## Example Data Model
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The following example showcase a data model with common definitions:
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```ts
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import {
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BeforeCreate,
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Entity,
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Enum,
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OneToOne,
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PrimaryKey,
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Property,
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} from "@mikro-orm/core"
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import {
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createPsqlIndexStatementHelper,
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generateEntityId,
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} from "@medusajs/utils"
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import ProductVariant from "./product-variant"
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export enum MediaType {
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MAIN = "main",
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PREVIEW = "preview"
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}
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const VariantIdIndex = createPsqlIndexStatementHelper({
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name: "IDX_product_media_variant_id",
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tableName: "product_media",
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columns: "variant_id",
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}).MikroORMIndex
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@Entity({ tableName: "product_media" })
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export default class ProductMedia {
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@PrimaryKey({ columnType: "text" })
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id: string
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@Property({ columnType: "text" })
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name: string
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@Enum({ items: ["main", "preview"] })
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type: MediaType
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@Property({ columnType: "text" })
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file_key: string
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@Property({ columnType: "text" })
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mime_type: string
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@VariantIdIndex()
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@Property({ columnType: "text" })
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variant_id: string
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@OneToOne({
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entity: ProductVariant,
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onDelete: "cascade",
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})
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variant: ProductVariant
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@BeforeCreate()
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onCreate() {
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this.id = generateEntityId(this.id, "promed")
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}
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}
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```
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In the example above:
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- The `ProductMedia` data model has the columns `id`, `name`, `type`, `file_key`, `mime_type`, and `variant_id`.
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- The data model has an index on the `variant_id` column.
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- The data model has a one-to-one relation to the `ProductVariant` data model.
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