apollo-transform-utils

apollo-transform-utils

Utility transforms to be used as graphql-tools transforms

Getting Started

Install apollo-transform-utils with

$ npm i apollo-transform-utils

or

$ yarn add apollo-transform-utils

and use them within your delegateToSchema resolvers:

const { Debug, PickTransform, InlineFragmentTransform, NestTransform } = require('apollo-transform-utils')

const transforms = [
  new PickTransform(fieldName),
  new InlineFragmentTransform('ContactInfo')
  new NestTransform(`${fieldName}.user.info`),
  new Debug()
]

// within resolver
return info.mergeInfo
    .delegateToSchema({
      schema: info.schema,
      operation: info.operation.operation,
      fieldName,
      args,
      context,
      info,
      transforms
    })

Usage

NestTransform(path: string)

Place your current selection set under a specified period-delimited path

Example

const { NestTransform } = require('apollo-transform-utils')

const path = 'user.contactInfo'

const transforms = [
  new NestTransform(path)
]

/*
 * { number } -> { user { contactInfo { number } } }
 */

PickTransform(path: string)

Opposite of NestTransform. Select selections along a period-delimited path.

Example

const { PickTransform } = require('apollo-transform-utils')

const path = 'user.contactInfo'

const transforms = [
  new PickTransform(path)
]

/*
 * { user { contactInfo { number } } } -> { number }
 */

InlineFragmentTransform(typeName: string)

Nest your currently selection under a inline fragment of type typeName

Example

const { InlineFragmentTransform } = require('apollo-transform-utils')

const typeName = 'User'

const transforms = [
  new InlineFragmentTransform(typeName)
]

/*
 * { id } -> { ... on User { id } }
 */

DocumentTransform(query: string | Document)

Creates a new document and replaces the string __SELECTIONS__ with your current selection set.

Example

const { DocumentTransform } = require('apollo-transform-utils')

const newDocument = `
  query {
    user {
      friends {
        ${DocumentTransform.__SELECTIONS__}
      }
    }
  }
`

const transforms = new DocumentTransform(newDocument)

/*
 * { id } -> { user { friends { id } } }
 */

Debug

Transform that pretty prints the current operation's document and variables. Super helpful for determining intermediate results between transforms.

Example

const { Debug, PickTransform, InlineFragmentTransform, NestTransform } = require('apollo-transform-utils')

const transforms = [
  new Debug(),
    new PickTransform(fieldName),
  new Debug(),
    new InlineFragmentTransform('ContactInfo')
  new Debug(),
    new NestTransform(`${fieldName}.user.info`),
  new Debug()
]

Utilities

nest(path: string, selections: Array<FieldNode>)

Used by NestTransform, but can be used as a standalone function to nest selections under a certain path.

pick(path: string, selections: Array<FieldNode>)

Used by PickTransform, but can be used as a standalone function to pick a node along the path from a selection set.