nexus/src/definitions/list.ts

Scalable, strongly typed GraphQL schema development

import { isType } from 'graphql'
import { isNexusMeta } from './nexusMeta'
import { isNexusStruct, NexusListableTypes } from './wrapping'
import { NexusTypes, withNexusSymbol } from './_types'

export class NexusListDef<TypeName extends NexusListableTypes> {
  // @ts-ignore
  // Required field for TS to differentiate NonNull from Null from List
  private _isNexusListDef: boolean = true

  constructor(readonly ofNexusType: TypeName) {
    /* istanbul ignore if */
    if (
      typeof ofNexusType !== 'string' &&
      !isNexusStruct(ofNexusType) &&
      !isNexusMeta(ofNexusType) &&
      !isType(ofNexusType)
    ) {
      throw new Error('Cannot wrap unknown types in list(). Saw ' + ofNexusType)
    }
  }
}

withNexusSymbol(NexusListDef, NexusTypes.List)

export function list<TypeName extends NexusListableTypes>(type: TypeName): NexusListDef<TypeName> {
  return new NexusListDef(type)
}