---
title: Context
description: Define a shared context for route handlers and middleware
---

## Route Context

Route handlers and middleware share a mutable context object per request.
Use `context.set()` to store values and `context.get()` to read them.
Use `route.$context<T>()` to strongly type the context for set of routes or a single route.

```ts
const authenticatedRoute = route.$context<{
	user: { id: string; name: string };
}>();
```

## Global Context

To avoid having to specify a context type for every route, you can define a default context type for you application globally.

```ts
declare module "@rest-rpc/express" {
	interface DefaultContext {
		env: {
			DATABASE_URL: string;
		};
	}
}
```

:::tip
When declaring required properties use a centralized middleware that runs before downstream middleware or handlers try to access the properties.
This avoids runtime errors when a property is not set in the context even though the type system indicates that it is present.
:::