# `relay-edge-types`

- Category: `Schema`
- Rule name: `@graphql-eslint/relay-edge-types`
- Requires GraphQL Schema: `true` [ℹ️](../../README.md#extended-linting-rules-with-graphql-schema)
- Requires GraphQL Operations: `false` [ℹ️](../../README.md#extended-linting-rules-with-siblings-operations)

Set of rules to follow Relay specification for Edge types.

- A type that is returned in list form by a connection type's `edges` field is considered by this spec to be an Edge type
- Edge type must be an Object type
- Edge type must contain a field `node` that return either Scalar, Enum, Object, Interface, Union, or a non-null wrapper around one of those types. Notably, this field cannot return a list
- Edge type must contain a field `cursor` that return either String, Scalar, or a non-null wrapper around one of those types
- Edge type name must end in "Edge" _(optional)_
- Edge type's field `node` must implement `Node` interface _(optional)_
- A list type should only wrap an edge type _(optional)_

## Usage Examples

### Correct

```graphql
# eslint @graphql-eslint/relay-edge-types: 'error'

type UserConnection {
  edges: [UserEdge]
  pageInfo: PageInfo!
}
```

## Config Schema

The schema defines the following properties:

### `withEdgeSuffix` (boolean)

Edge type name must end in "Edge".

Default: `true`

### `shouldImplementNode` (boolean)

Edge type's field `node` must implement `Node` interface.

Default: `true`

### `listTypeCanWrapOnlyEdgeType` (boolean)

A list type should only wrap an edge type.

Default: `true`

## Resources

- [Rule source](../../packages/plugin/src/rules/relay-edge-types.ts)
- [Test source](../../packages/plugin/tests/relay-edge-types.spec.ts)