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Dependency Container

In this document, you’ll learn what the dependency container is and how you can use it in Medusa.

Introduction

What is Dependency Injection

Dependency Injection is the act of delivering the required resources to a class. These resources are the class’s dependencies. This is usually done by passing (or injecting) the dependencies in the constructor of the class.

Generally, all resources are registered in a container. Then, whenever a class depends on one of these resources, the system retrieves the resources from the container and injects them into the class’s constructor.

Medusa’s Dependency Container

Medusa uses a dependency container to register essential resources of your server. You can then access these resources in classes and endpoints using the dependency container.

For example, if you create a custom service, you can access any other service registered in Medusa in your service’s constructor. That includes Medusa’s core services, services defined in plugins, or other services that you create on your server.

You can load more than services in your Medusa server. You can load the Entity Manager, logger instance, and much more.

MedusaContainer

To manage dependency injections, Medusa uses Awilix. Awilix is an NPM package that implements dependency injection in Node.js projects.

When you run the Medusa server, a container of the type Copy to Clipboard is created. This type extends the AwilixContainer object.

The server then registers all important resources in the container, which makes them accessible in classes and endpoints.

Registered Resources

The Medusa server scans the core Medusa package, plugins, and your files in the Copy to Clipboard directory and registers the following resources:

Many resources are registered under their camel-case name. These resources are formatted by taking the name of the file, transforming it to camel case, then appending the folder name to the name. So, the Copy to Clipboard service is registered as Copy to Clipboard.

Resource

Description

Registration Name

Configurations

The configurations that are exported from medusa-config.js.

Copy to Clipboard

Services

Services that extend the Copy to Clipboard class.

Each service is registered under its camel-case name. For example, the Copy to Clipboard is registered as Copy to Clipboard.

Entity Manager

An instance of Typeorm’s Entity Manager.

Copy to Clipboard

Logger

An instance of Medusa CLI’s logger. You can use it to log messages to the terminal.

Copy to Clipboard

Single Payment Provider

An instance of every payment provider that extends the Copy to Clipboard class.

Every payment provider is registered under two names:

  • Its camel-case name. For example, the Copy to Clipboard is registered as Copy to Clipboard.
  • Copy to Clipboard followed by its identifier. For example, the Copy to Clipboard is registered as Copy to Clipboard.

All Payment Providers

An array of all payment providers that extend the Copy to Clipboard class.

Copy to Clipboard

Single Fulfillment Provider

An instance of every fulfillment provider that extends the Copy to Clipboard class.

Every fulfillment provider is registered under two names:

  • Its camel-case name. For example, the Copy to Clipboard is registered as Copy to Clipboard.
  • Copy to Clipboard followed by its identifier. For example, the Copy to Clipboard is registered as Copy to Clipboard.

All Fulfillment Providers

An array of all fulfillment providers that extend the Copy to Clipboard class.

Copy to Clipboard

Single Notification Provider

An instance of every notification provider that extends the Copy to Clipboard or the Copy to Clipboard classes.

Every notification provider is registered under two names:

  • Its camel-case name. For example, the Copy to Clipboard is registered as Copy to Clipboard.
  • Copy to Clipboard followed by its identifier. For example, the Copy to Clipboard is registered as Copy to Clipboard.

All Notification Providers

An array of all notification providers that extend the Copy to Clipboard or the Copy to Clipboard classes.

Copy to Clipboard

File Service

An instance of the class that extends the Copy to Clipboard class, if any.

The file service is registered under two names:

  • Its camel-case name. For example, the Copy to Clipboard is registered as Copy to Clipboard.
  • Copy to Clipboard

Search Service

An instance of the class that extends the Copy to Clipboard or the Copy to Clipboard classes, if any.

The search service is registered under two names:

  • Its camel-case name. For example, the Copy to Clipboard is registered as Copy to Clipboard.
  • Copy to Clipboard

Single Tax Provider

An instance of every tax provider that extends the Copy to Clipboard class.

The tax provider is registered under two names:

  • Its camel-case name.
  • Copy to Clipboard followed by its identifier.

All Tax Providers

An array of every tax provider that extends the Copy to Clipboard class.

Copy to Clipboard

Oauth Services

An instance of every service that extends the Copy to Clipboard class.

Each Oauth Service is registered under its camel-case name followed by Copy to Clipboard.

Feature Flag Router

An instance of the Copy to Clipboard. This can be used to list feature flags, set a feature flag’s value, or check if they’re enabled.

Copy to Clipboard

Redis

An instance of the Redis client. If Redis is not configured, a fake Redis client is registered.

Copy to Clipboard

Single Entity

An instance of every entity.

Each entity is registered under its camel-case name followed by Model. For example, the Copy to Clipboard entity is stored under Copy to Clipboard.

All Entities

An array of all database entities that is passed to Typeorm when connecting to the database.

Copy to Clipboard

Repositories

An instance of each repository.

Each repository is registered under its camel-case name. For example, Copy to Clipboard is stored under Copy to Clipboard.

Single Batch Job Strategy

An instance of every class extending the Copy to Clipboard class.

Each batch job strategy is registered under three names:

  • Its camel-case name. For example, Copy to Clipboard is registered as Copy to Clipboard.
  • Copy to Clipboard followed by its identifier. For example, the Copy to Clipboard is registered under Copy to Clipboard.
  • Copy to Clipboard followed by its batch job type. For example, the Copy to Clipboard is registered under Copy to Clipboard.

All Batch Job Strategies

An array of all classes extending the Copy to Clipboard abstract class.

Copy to Clipboard

Tax Calculation Strategy

An instance of the class implementing the Copy to Clipboard interface.

Copy to Clipboard

Cart Completion Strategy

An instance of the class extending the Copy to Clipboard class.

Copy to Clipboard

Price Selection Strategy

An instance of the class implementing the Copy to Clipboard interface.

Copy to Clipboard

Strategies

An instance of strategies that aren’t of the specific types mentioned above and that are under the Copy to Clipboard directory.

Its camel-case name.

Loading Resources

This section covers how to load resources that the Medusa server registers when it starts running.

In Endpoints

To load resources, such as services, in endpoints, use the Copy to Clipboard function. The function receives the registration name of the resource as a parameter.

For example:

Report Incorrect CodeReport Incorrect CodeReport Incorrect CodeCopy to Clipboard
const logger = req.scope.resolve('logger');
Copy to Clipboard

Please note that in endpoints some resources, such as repositories, are not available.

In Classes

In classes such as services, strategies, or subscribers, you can load resources in the constructor function. The constructor receives an object of dependencies as a first parameter. Each dependency in the object should use the registration name of the resource that should be injected to the class.

For example:

Report Incorrect CodeReport Incorrect CodeReport Incorrect CodeCopy to Clipboard
import { OrderService } from '@medusajs/medusa';

class OrderSubscriber {
protected orderService: OrderService;

constructor({ orderService }) {
this.orderService = orderService;
}
}
Copy to Clipboard

What’s Next