# Production App

This example includes a relatively fully featured app to demonstrate how real-world applications can be built with Grats.

**[https://github.com/captbaritone/grats/tree/main/examples/production-app/](https://github.com/captbaritone/grats/tree/main/examples/production-app/)**

## Features

-   [Node interface](https://graphql.org/learn/global-object-identification/)
-   [dataloader](https://github.com/graphql/dataloader)
-   [Connections](https://relay.dev/graphql/connections.htm) (as used by Relay)
-   Subscriptions - See `Subscription.postLikes` in `models/LikeConnection.ts`
-   `@stream`\ - For expensive lists like `Viewer.feed` in `models/Viewer.ts`
-   Custom scalars - See `Date` defined in `graphql/CustomScalars.ts`
-   [OneOf input types](../docblock-tags/oneof-inputs.md) for modeling Markdown content in `models/Post.ts`
-   Look-ahead optimization for Connections to use count query for requests that only read count in `graphql/gqlUtils.ts`.
-   A custom `@cost` field directive which implements API rate limiting, were some fields cost "credits" to read.

## Implementation notes

Dataloaders are attached to the per-request viewer context. This enables per-request caching while avoiding the risk of leaking data between requests/users.

The viewer context is passed all the way through the app to the data layer. This would enable permission checking to be defined as close to the data as possible.

## Libraries used

-   `graphql-yoga`
-   `graphql-js`
-   `dataloader`
-   `@graphql-yoga/plugin-defer-stream`
-   `graphql-relay`