yunoo / graphql-pagination-transform

Transform GraphQL fields into relay connections using a @connection directive

GraphQL pagination transform

Transforms GraphQL schema fields into a relay connections using a @connection directive.

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Features

• Create the needed Connection and Edge object types.
• Reassign the type of marked fields to the Connection type.
• Remove any @connection directives.
• Generate the PageInfo object type if it hasn't been defined.
• Support non-nullable types
• Throw errors if the generated Connection and Edge types have a name conflict with types already defined in your SDL.
• Leave everything else in your SDL untouched.
• Apply cacheControl directives to Connection and Edge types if exist.
• Works with Apollo Federation schemas

Usage examples

1. Install library

npm install --save graphql-pagination-transform

2. Add @connection directive to the fields in your schema that needs to be transformed into relay connections.

3. Import connecton directive from this lib

import { connectionDirective } from 'graphql-pagination-transform'

const { connectionDirectiveTypeDefs } = connectionDirective()

4. Merge it with your schema type definitions

import gql from 'graphql'
import typeDefs from './typeDefs' // Path to your schema type definitions

const schema = gql([typeDefs, connectionDirectiveTypeDefs])

export default schema

or using mergeTypeDefs from graphql-tools in case your type definitions are DocumentNode's

import { mergeTypeDefs } from '@graphql-tools/merge'
import typeDefs from './typeDefs' // Path to your schema type definitions

const schema = mergeTypeDefs([assetTypeDefs, scalarTypes, directiveTypeDefs])

export default schema

5. Transform type definitions. This will remove all @connection directives and create connection types with edges, nodes and pageInfo

import transform from 'graphql-directive-connection'
impot schema from './schema'

const result = transform({ typeDefs, cacheControl: { enable: true, apollo: true } })

Transformation result is a string representation of your type definitions. You will probaly want to convert it to GraphQLSchema type later. This could be archived using graphql-tools makeExecutableSchema or Apollo buildSubgraphSchema (for Apollo Federation).

cacheControl directives

This plugin will apply cacheControl directive on Connection type, edge and pageInfo fields by default.

Remember to add cacheControl directive to your schema in case you are not explicitly disabling it in a transform function.

enum CacheControlScope {
  PUBLIC
  PRIVATE
}

directive @cacheControl(
  maxAge: Int
  scope: CacheControlScope
  inheritMaxAge: Boolean
) on FIELD_DEFINITION | OBJECT | INTERFACE | UNION

In order to completely ignore cache arguments and disable cacheControl directive pass cacheControl: false or cacheControl: { enable: false } argument to transform (default plugin export) function. The package will then use the largest maxAge across the connection fields with custom types and apply it to non-scalar fields and types (e.g. edges, node and pageInfo).

GraphQL Apollo v3 and later supports inheritMaxAge argument which forces a particular field to inherit the maxAge of its parent field. You can enable this feature by passing cacheControl: { enable: true, apollo: true } to a transform function.

Keep in mind that due to the modified cacheControl heuristics in Apollo v3+ this could technically make any queries with Connection types uncacheable (see https://www.apollographql.com/docs/apollo-server/performance/caching/#why-are-these-the-maxage-defaults). Enabling defaultMaxAge across your GraphQL implementation might partially solve the problem, but only for Apollo v2 and lower versions. Thus, it is recommended to leave cacheControl directives enabled.

Authors

• taylrun - Initial idea
• Yunoo - Lib re-write and development