Stitching API

`stitchSchemas`

This is the main function that implements schema stitching. It accepts all the same arguments as makeExecutableSchema, and the additions below:

import { stitchSchemas } from '@graphql-tools/stitch'
 
stitchSchemas({
  subschemas?: Array<GraphQLSchema | SubschemaConfig | Array<SubschemaConfig>>
  types?: Array<GraphQLNamedType>
  typeDefs?: ITypeDefinitions
  resolvers?: IResolvers<any, TContext> | Array<IResolvers<any, TContext>>
  mergeDirectives?: boolean
  mergeTypes?: boolean | Array<string> | MergeTypeFilter
  typeMergingOptions?: TypeMergingOptions
  onTypeConflict?: OnTypeConflict
  subschemaConfigTransforms?: Array<SubschemaConfigTransform>
}): GraphQLSchema
 
export interface TypeMergingOptions {
  typeDescriptionsMerger?: (candidates: Array<MergeTypeCandidate>) => string
  fieldConfigMerger?: (candidates: Array<MergeFieldConfigCandidate>) => GraphQLFieldConfig<any, any>
  inputFieldConfigMerger?: (candidates: Array<MergeInputFieldConfigCandidate>) => GraphQLInputFieldConfig
}
 
export type OnTypeConflict = (
  left: GraphQLNamedType,
  right: GraphQLNamedType,
  info?: {
    left: {
      subschema?: GraphQLSchema | SubschemaConfig
      transformedSubschema?: Subschema
    }
    right: {
      subschema?: GraphQLSchema | SubschemaConfig
      transformedSubschema?: Subschema
    }
  }
) => GraphQLNamedType

subschemas: an array of schema-like objects. These subschemas are wrapped with proxying resolvers in the final schema.
types: additional types to add to the final type map, most useful for custom scalars or enums.
typeDefs: strings or parsed documents that contain additional types or type extensions. Type extensions are always applied last.
resolvers: accepts standard resolvers with the addition of specifying a selectionSet.
mergeTypes: specifies a strategy for handling duplicated types.
typeMergingOptions: allows customization of automatic type merging.
onTypeConflict: allows customization of manual type resolution.

`createMergedTypeResolver`

Creates a merged type resolver that may be wrapped with custom behaviors.

import { createMergedTypeResolver } from '@graphql-tools/stitch'
 
createMergedTypeResolver({
  fieldName?: string
  args?: (originalResult: any) => Record<string, any>
  argsFromKeys?: (keys: ReadonlyArray<K>) => Record<string, any>
  valuesFromResults?: (results: any, keys: ReadonlyArray<K>) => Array<V>
}): MergedTypeResolver

`forwardArgsToSelectionSet`

Creates a dynamic selectionSet that forwards gateway arguments to a resolver selection hint.

import { forwardArgsToSelectionSet } from '@graphql-tools/stitch';
 
forwardArgsToSelectionSet(
  selectionSet: string,
  mapping?: Record<string, string[]>
) => (field: FieldNode) => SelectionSetNode

Last updated on October 4, 2022

Extending Stitched Schemas Federation to Stitching