# evaluate

Learn how to evaluate a CQL query on the server.

This function evaluates a [CQL](/reference/cql) query against the current visitor's context on the server.

Call it from a loader, passing the loader's context as the `scope` option, to personalize or segment the response before it renders.

## Signature

This function has the following signature:

```ts
function evaluate<T extends JsonValue>(query: string, options: EvaluationOptions<T>): Promise<T>;
```

## Example

Evaluate a query in a loader:

**app/routes/\_index.tsx**

```ts
import {evaluate} from '@croct/plug-hydrogen/server';

const country = await evaluate<string | null>("location's country", {
  scope: context,
});
```

## Parameters

The following list describes the supported parameters:

- `query`: `string`

  The CQL query to evaluate.

- `options`: `object`

  The evaluation options.

  - `scope`: `CroctContext`

    The Hydrogen load context for the current request.

  - `context`: `EvaluationContext` (optional)

    The evaluation context to attach to the query. Use it to pass custom attributes that personalize or segment the result. These values are accessible in the [context variable](/reference/cql/context#evaluation).

  - `fallback`: `T` (optional)

    The value to return when the evaluation fails, such as on a network error or timeout.