medusa-store/www/apps/resources/app/commerce-modules/region/links-to-other-modules/page.mdx

import { CodeTabs, CodeTab } from "docs-ui"

export const metadata = {
  title: `Links between Region Module and Other Modules`,
}

# {metadata.title}

This document showcases the module links defined between the Region Module and other commerce modules.

## Summary

The Region Module has the following links to other modules:

<Note title="Tip">

Read-only links are used to query data across modules, but the relations aren't stored in a pivot table in the database.

</Note>

- [`Region` data model \<\> `Cart` data model of the Cart Module](#cart-module). (Read-only)
- [`Region` data model \<\> `Order` data model of the Order Module](#order-module). (Read-only)
- [`Region` data model \<\> `PaymentProvider` data model of the Payment Module](#payment-module).

---

## Cart Module

Medusa defines a read-only link between the `Region` data model and the [Cart Module](../../cart/page.mdx)'s `Cart` data model. This means you can retrieve the details of a region's carts, but you don't manage the links in a pivot table in the database. The region of a cart is determined by the `region_id` property of the `Cart` data model.

### Retrieve with Query

To retrieve the carts of a region with [Query](!docs!/learn/fundamentals/module-links/query), pass `carts.*` in `fields`:

<CodeTabs group="relation-query">
  <CodeTab label="query.graph" value="method">

```ts
const { data: regions } = await query.graph({
  entity: "region",
  fields: [
    "carts.*",
  ],
})

// regions.carts
```

  </CodeTab>
  <CodeTab label="useQueryGraphStep" value="step">

```ts
import { useQueryGraphStep } from "@medusajs/medusa/core-flows"

// ...

const { data: regions } = useQueryGraphStep({
  entity: "region",
  fields: [
    "carts.*",
  ],
})

// regions.carts
```

  </CodeTab>
</CodeTabs>

---

## Order Module

Medusa defines a read-only link between the `Region` data model and the [Cart Module](../../cart/page.mdx)'s `Cart` data model. This means you can retrieve the details of a region's orders, but you don't manage the links in a pivot table in the database. The region of an order is determined by the `region_id` property of the `Order` data model.

### Retrieve with Query

To retrieve the orders of a region with [Query](!docs!/learn/fundamentals/module-links/query), pass `orders.*` in `fields`:

<CodeTabs group="relation-query">
  <CodeTab label="query.graph" value="method">

```ts
const { data: regions } = await query.graph({
  entity: "region",
  fields: [
    "orders.*",
  ],
})

// regions.orders
```

  </CodeTab>
  <CodeTab label="useQueryGraphStep" value="step">

```ts
import { useQueryGraphStep } from "@medusajs/medusa/core-flows"

// ...

const { data: regions } = useQueryGraphStep({
  entity: "region",
  fields: [
    "orders.*",
  ],
})

// regions.orders
```

  </CodeTab>
</CodeTabs>

---

## Payment Module

You can specify for each region which payment providers are available for use.

Medusa defines a module link between the `PaymentProvider` and the `Region` data models.

![A diagram showcasing an example of how resources from the Payment and Region modules are linked](https://res.cloudinary.com/dza7lstvk/image/upload/v1711569520/Medusa%20Resources/payment-region_jyo2dz.jpg)

### Retrieve with Query

To retrieve the payment providers of a region with [Query](!docs!/learn/fundamentals/module-links/query), pass `payment_providers.*` in `fields`:

<CodeTabs group="relation-query">
  <CodeTab label="query.graph" value="method">

```ts
const { data: regions } = await query.graph({
  entity: "region",
  fields: [
    "payment_providers.*",
  ],
})

// regions.payment_providers
```

  </CodeTab>
  <CodeTab label="useQueryGraphStep" value="step">

```ts
import { useQueryGraphStep } from "@medusajs/medusa/core-flows"

// ...

const { data: regions } = useQueryGraphStep({
  entity: "region",
  fields: [
    "payment_providers.*",
  ],
})

// regions.payment_providers
```

  </CodeTab>
</CodeTabs>

### Manage with Link

To manage the payment providers in a region, use [Link](!docs!/learn/fundamentals/module-links/link):

<CodeTabs group="relation-link">
  <CodeTab label="link.create" value="method">

```ts
import { Modules } from "@medusajs/framework/utils"

// ...

await link.create({
  [Modules.REGION]: {
    region_id: "reg_123",
  },
  [Modules.PAYMENT]: {
    payment_provider_id: "pp_stripe_stripe",
  },
})
```

  </CodeTab>
  <CodeTab label="createRemoteLinkStep" value="step">

```ts
import { Modules } from "@medusajs/framework/utils"
import { createRemoteLinkStep } from "@medusajs/medusa/core-flows"

// ...

createRemoteLinkStep({
  [Modules.REGION]: {
    region_id: "reg_123",
  },
  [Modules.PAYMENT]: {
    payment_provider_id: "pp_stripe_stripe",
  },
})
```

  </CodeTab>
</CodeTabs>