medusa-store/www/docs/content/modules/multiwarehouse/stock-location-module.md

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In this document, you’ll learn about the inventory module, how it works, and its relation to other processes in your commerce application.

Stock Level Module

In this document, you’ll learn about the Stock Level module and how it works.

Overview

A stock location indicates a physical address that stock-kept items can be stored in. The stock location module handles functionalities related to managing stock locations and their addresses.

Medusa's Stock Location module is a standalone module that can be used in any commerce application, not just in a Medusa backend. This document gives a general overview of how the stock location module is designed, and highlights how the Medusa core orchestrates relations around this module when it's used with the Medusa backend.

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StockLocation Entity

The StockLocation entity represents a stock location. It has minimal attributes including a name attribute. It’s associated with the StockLocationAddress entity.

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StockLocationAddress Entity

The StockLocationAddress is an entity that contains address-related fields, such as city or country_code.

The StockLocationAddress entity belongs to the StockLocation entity. It is used to store the address details of a stock location.

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How the Module Integrates into Medusa

This section explains how the Medusa backend uses the stock location module along with its entities and other modules.

Entities Relation Overview

The following entities in the Medusa backend each have an attribute that is used to associate them with a stock location:

• Fulfillment: The location_id attribute within the Fulfillment entity is used to indicate from which stock location an order item is fulfilled.
• Return: The location_id attribute within the Return entity is used to indicate to which stock location an order item is returned.
• Store: The default_location_id attribute within the Store entity is used to indicate the default stock location to use in the ecommerce store.
• SalesChannelLocation: This entity is used to attach a stock location to a SalesChannel. The relation between these two entities is explained further in the Relation to Sales Channel section.

When the Medusa's Stock Location module is used with the Medusa backend, the ID that is associated with the attributes mentioned above is from the StockLocation module.

The Medusa backend also orchestrates between different modules. The Inventory Module's entities contain the following attributes to handle associations between them and a stock location:

• InventoryLevel: This entity is used to indicate the stocked quantity of an inventory item in a stock location. As explained in the Inventory Module documentation, the InventoryLevel entity has an attribute location_id.
• ReservationItem: This entity is used to indicate the reserved quantity of an inventory item in a stock location. As explained in the Inventory Module documentation, the ReservationItem entity has an attribute location_id.

When both modules are used within the Medusa backend, the Medusa backend bridges between these modules by passing the ID of a StockLocation from the stock location module to the inventory module, and the inventory module uses the ID in its entities.

Relation to SalesChannel

A stock location can be associated with more than one sales channel. For example, a physical store and an online store can use the same stock location.

As the StockLocation and SalesChannel entities are available in separate modules, the Medusa backend handles attaching the stock location with the sales channel within the SalesChannelLocation entity.

This relation is used across the Medusa backend and within checkout and order workflows:

• When checking the availability of an inventory item during checkout, the Medusa backend retrieves the location IDs that are associated with the cart’s sales channel using the SalesChannelLocation, then passes it along to the inventory module to perform the quantity check.
• When an order is placed, the Medusa backend retrieves the location IDs that are associated with the cart’s sales channel using the SalesChannelLocation entity, and passes it to the inventory module that reserves the ordered quantity of the inventory item from that location. The admin can later change the stock location if necessary.
• When an item in an order is fulfilled, the admin chooses a stock location to fulfill the item from. Similarly, when an item in an order is returned, the admin can choose a stock location to return the item to. The Medusa backend then passes the ID of the location from the stock module to the inventory module to perform inventory management functionalities.