Use Discounts in Checkout

In this document, learn how to use discounts during checkout on the storefront.

You can check out the Discounts Architecture documentation to learn more about how discounts work.

Overview

Customers can use discounts during checkout to benefit from promotions that the merchant provides. Discounts are added to a cart using its unique code.

In this document, you’ll learn how to add a discount to a cart, how to display details related to the discount, and how to remove a discount from a cart.

Scenario

You want to implement discount functionality in your store to allow customers to apply discount codes to their cart and remove them from the cart. You also want to display the discount details for the customer.

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Prerequisites

Medusa Components

It's assumed that you already have a Medusa backend installed and set up. If not, you can follow the quickstart guide to get started.

It is also assumed you already have a storefront set up. It can be a custom storefront or one of Medusa’s storefronts. If you don’t have a storefront set up, you can install the Next.js starter storefront.

JS Client

This guide includes code snippets to send requests to your Medusa backend using Medusa’s JS Client, among other methods.

If you follow the JS Client code blocks, it’s assumed you already have Medusa’s JS Client installed and have created an instance of the client.

Medusa React

This guide also includes code snippets to send requests to your Medusa backend using Medusa React, among other methods.

If you follow the Medusa React code blocks, it's assumed you already have Medusa React installed and have used MedusaProvider higher in your component tree.

It's also assumed you already have used CartProvider higher in your component tree.

Previous Steps

This document assumes you’ve already taken care of the add-to-cart flow. So, you should have a cart created for the customer with at least one product in it.

You can learn how to implement the cart flow using this documentation.

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Add Discount to Cart

The customer can enter a discount code during the checkout flow to benefit from a promotion.

You can add a discount to a customer’s cart by sending the Update Cart request:

• Medusa JS Client
• Medusa React
• Fetch API

medusa.carts.update(cartId, {
  discounts: [
    {
      code,
    },
  ],
})
.then(({ cart }) => {
  console.log(cart.discounts)
})
.catch((e) => {
  // display an error to the customer
  alert("Discount is invalid")
})

import { useCart } from "medusa-react"

const Cart = () => {
  // ...

  const { updateCart } = useCart()

  const addDiscount = (code: string) => {
    updateCart.mutate({
      discounts: [
        {
          code,
        },
      ],
    })
  }

  // ...
}

export default Cart

fetch(`<BACKEND_URL>/store/carts/${cartId}`, {
  method: "POST",
  credentials: "include",
  body: JSON.stringify({
    discounts: [
      {
        code,
      },
    ],
  }),
  headers: {
    "Content-Type": "application/json",
  },
})
.then((response) => response.json())
.then(({ cart }) => {
  console.log(cart.discounts)
})
.catch((e) => {
  // display an error to the customer
  alert("Discount is invalid")
})

This request requires the customer’s cart ID as a path parameter. In the body of the request, you can update many cart-related details, including adding discounts by passing the discounts field. It is an array of objects, with each object having a property code with its value being the discount’s unique code.

Customers can add more than one discount to their cart, however, only one non-free shipping discount is allowed per cart.

If the discount is applied successfully, the entire cart object will be returned. You can access the discounts applied on the cart in the cart.discounts array.

In case the customer enters an invalid discount or the discount cannot be applied to the cart because it doesn’t meet its conditions, the request will return an error. You can handle the error in the catch method.

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Display Discount Details

After the customer enters a discount code and it is applied to the cart, you can display the discount details to the customer. This shows the customer how much they benefitted from the discount.

The previous request returns the full cart object with different fields that can be used to display the discount details depending on the discount type.

Display Discount Information

In the returned cart object, all discounts applied can be found in the discounts array. The following properties can be used to display the discount information:

{
  "discounts": [
    {
      "code": "TEST",
      "is_dynamic": false,
      "starts_at": "2022-12-01T15:09:21.149Z",
            "ends_at": null,
      "usage_limit": null,
      "usage_count": 0,
      "rule": {
          "description": "percentage discount",
          "type": "percentage",
          "value": 20,
          "allocation": "total",
          "conditions": [
            //...
          ],
          //...
      },
      //...
    }
  ],
  //...
}

• The code property is the code of the discount. This is the code that the customer enters to apply the discount.
• The starts_at and ends_at indicate the start and expiry dates of the discount. If there’s no end date, the ends_at property will be null.
• The usage_limit property indicates if there is any usage limit set on the discount. The usage_count property indicates how many times this discount has been used.
• The rule property includes details related to the type of discount, its value, and its conditions if there are any.

Display Item Discounts

In the returned cart object, the property items is an array of items in the cart. If a discount is applied to an item, the following properties inside the item can be used to get the item-specific discount details:

{
  "items": [
    {
      "adjustments": [
        {
          "description": "discount",
          "discount_id": "disc_01GK73RBCRXXT8HWEYMQE4RCY6",
          "amount": 730,
          //...
        }
      ],
      "subtotal": 3650,
      "discount_total": 730,
      "total": 2920,
      //...
    }
  ]
}

• The adjustments property is an array of objects, each containing details about the adjustment made to the item. Discounts applied to the item will be represented by an adjustment in this array. It will have the description property with the value discount, the discount_id property, and the amount of the discount.
• The subtotal property is the price before the discounts are applied.
• The discount_total property is the sum of all discount amounts.
• The total property is the total of the item after applying the discounts.

Display Cart Discounts

The returned cart object has the following properties that can be used to display cart’s general discount details:

{
  "subtotal": 11550,
  "discount_total": 1910,
  "shipping_total": 0,
  "total": 9640,
  //...
}

• The subtotal property is the total of the cart before applying any discount.
• The discount_total property is the total discount amounts applied to the cart.
• The shipping_total property is the total shipping amount. If a Free Shipping discount is applied to the cart, shipping_total and discount_total will be 0.
• The total property is the total amount of the cart after applying the discount.

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Remove Discount from Cart

The customer can choose to remove a discount from their cart.

You can remove a discount from a customer’s cart using the Remove Discount request:

• Medusa JS Client
• Fetch API

medusa.carts.deleteDiscount(cartId, code)
.then(({ cart }) => {
  console.log(cart.discounts)
})

fetch(`<BACKEND_URL>/store/carts/${cartId}/discounts/${code}`, {
  method: "DELETE",
  credentials: "include",
})
.then((response) => response.json())
.then(({ cart }) => {
  console.log(cart.discounts)
})

This request accepts the cart ID and the code of the discount to remove. If the discount is removed successfully, the request returns the updated cart object, where you won’t find the discount in the discounts array anymore.

The totals of the cart and its items will be updated as well.