> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mercurjs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Compute aggregate ratings

> Compute average ratings for products and sellers from server code.

In this guide, you'll learn how to compute average ratings for products and
sellers from your own server code. This is useful when surfacing a rating on a
storefront page or in a custom API route.

The Review module service computes averages on demand instead of storing a
denormalized column, so the numbers always reflect the current set of reviews.
Resolve the service from the container to use its rating helpers.

## Average for one target

`getAvgRating` returns the average rating for a single product or seller:

```ts title="src/api/custom/route.ts" theme={null}
import type { MedusaRequest, MedusaResponse } from "@medusajs/framework/http"
import { MercurModules } from "@mercurjs/types"

export async function GET(req: MedusaRequest, res: MedusaResponse) {
  const reviewModuleService = req.scope.resolve(MercurModules.REVIEW)

  const rating = await reviewModuleService.getAvgRating("seller", "sel_123")

  res.json({ rating })
}
```

The first argument is the target type (`"product"` or `"seller"`), the second is
its id. The method returns `null` when the target has no reviews yet.

## Ratings for a list

For list views, `getProductsWithRating` and `getSellersWithRating` return records
with their average rating joined in, so you don't fan out a call per row:

```ts theme={null}
const reviewModuleService = container.resolve(MercurModules.REVIEW)

const sellers = await reviewModuleService.getSellersWithRating([
  "id",
  "name",
])
// => [{ id, name, rating }, ...]
```

Pass the fields you want selected from the target table; each returned record
gains a `rating` field with the average.

<Tip>
  These helpers average across a target's linked reviews. Combine them with your
  own `status` filter if you only want `published` reviews to count toward the
  public number.
</Tip>