console/packages/libraries/federation-link-utils

GraphQL Hive - federation-link-utils

Hive is a fully open-source schema registry, analytics, metrics and gateway for GraphQL federation and other GraphQL APIs.

---

This library can be used to create custom features for GraphQL schemas backed by Federation's @link directive.

Features

• Link version support.
• Import as/namespacing support that follows the link spec.
• Only graphql as a peer dependency.

Usage

This library is for power users who want to develop their own Federation 2 @link feature(s). It enables you to define and support multiple versions of the feature and to easily reference the named imports. This includes official federation features if you choose to implement them yourself.

# schema.graphql

directive @example(eg: String!) on FIELD
extend schema @link(url: "https://specs.graphql-hive.com/example/v1.0", import: ["@example"])
type Query {
  user: User @example(eg: "query { user { id name } }")
}

type User {
  id: ID!
  name: String
}

// specs.ts
import { extractLinkImplementations } from '@graphql-hive/federation-link-utils'

const typeDefs = parse(sdl)
const { matchesImplementation, resolveImportName } = extractLinkImplementations(typeDefs);
if (matchesImplementation('https://specs.graphql-hive.com/example', 'v1.0')) {
  const examples: Record<string, string> = {}
  const exampleName = resolveImportName('https://specs.graphql-hive.com/example', '@example')
  visit(typeDefs, {
    FieldDefinition: node => {
      const example = node.directives?.find(d => d.name.value === exampleName)
      if (example) {
        examples[node.name.value] = (
          example.arguments?.find(a => a.name.value === 'eg')?.value as
            | StringValueNode
            | undefined
        )?.value
      }
    }
  })
  return examples
}

// result[0] ==> { user: "query { user { id name } }"}