fb67d90b64
- Split Module and Module Links to their own chapters - Add new docs on db operations and transactions in modules, multiple services, links with custom columns, etc... - Added a list of registered dependencies in a module container
114 lines
3.7 KiB
Plaintext
114 lines
3.7 KiB
Plaintext
export const metadata = {
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title: `${pageNumber} Module Isolation`,
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}
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# {metadata.title}
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In this chapter, you'll learn how modules are isolated, and what that means for your custom development.
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<Note title="Summary">
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- Modules can't access resources, such as services or data models, from other modules.
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- Use Medusa's linking concepts, as explained in the [Module Links chapters](../../module-links/page.mdx), to extend a module's data models and retrieve data across modules.
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</Note>
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## How are Modules Isolated?
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A module is unaware of any resources other than its own, such as services or data models. This means it can't access these resources if they're implemented in another module.
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For example, your custom module can't resolve the Product Module's main service or have direct relationships from its data model to the Product Module's data models.
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---
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## Why are Modules Isolated
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Some of the module isolation's benefits include:
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- Integrate your module into any Medusa application without side-effects to your setup.
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- Replace existing modules with your custom implementation, if your use case is drastically different.
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- Use modules in other environments, such as Edge functions and Next.js apps.
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---
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## How to Extend Data Model of Another Module?
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To extend the data model of another module, such as the `product` data model of the Product Module, use Medusa's linking concepts as explained in the [Module Links chapters](../../module-links/page.mdx).
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---
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## How to Use Services of Other Modules?
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If you're building a feature that uses functionalities from different modules, use a workflow whose steps resolve the modules' services to perform these functionalities.
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Workflows ensure data consistency through their roll-back mechanism and tracking of each execution's status, steps, input, and output.
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### Example
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For example, consider you have two modules:
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1. A module that stores and manages brands in your application.
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2. A module that integrates a third-party Content Management System (CMS).
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To sync brands from your application to the third-party system, create the following steps:
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export const stepsHighlights = [
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["1", "retrieveBrandsStep", "A step that retrieves brands using a brand module."],
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["14", "createBrandsInCmsStep", "A step that creates brands using a CMS module."],
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["25", "", "Add a compensation function to the step if an error occurs."]
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]
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```ts title="Example Steps" highlights={stepsHighlights}
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const retrieveBrandsStep = createStep(
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"retrieve-brands",
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async (_, { container }) => {
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const brandModuleService = container.resolve(
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"brandModuleService"
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)
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const brands = await brandModuleService.listBrands()
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return new StepResponse(brands)
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}
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)
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const createBrandsInCmsStep = createStep(
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"create-brands-in-cms",
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async ({ brands }, { container }) => {
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const cmsModuleService = container.resolve(
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"cmsModuleService"
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)
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const cmsBrands = await cmsModuleService.createBrands(brands)
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return new StepResponse(cmsBrands, cmsBrands)
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},
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async (brands, { container }) => {
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const cmsModuleService = container.resolve(
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"cmsModuleService"
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)
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await cmsModuleService.deleteBrands(
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brands.map((brand) => brand.id)
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)
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}
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)
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```
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The `retrieveBrandsStep` retrieves the brands from a brand module, and the `createBrandsInCmsStep` creates the brands in a third-party system using a CMS module.
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Then, create the following workflow that uses these steps:
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```ts title="Example Workflow"
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export const syncBrandsWorkflow = createWorkflow(
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"sync-brands",
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() => {
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const brands = retrieveBrandsStep()
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updateBrandsInCmsStep({ brands })
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}
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)
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```
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You can then use this workflow in an API route, scheduled job, or other resources that use this functionality.
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