graphql/utilities/typeFromAST.js.flow

A Query Language and Runtime which can target any service.

// @flow strict

import inspect from '../jsutils/inspect';
import { Kind } from '../language/kinds';
import {
  type NamedTypeNode,
  type ListTypeNode,
  type NonNullTypeNode,
} from '../language/ast';
import {
  type GraphQLNamedType,
  GraphQLList,
  GraphQLNonNull,
} from '../type/definition';
import { type GraphQLSchema } from '../type/schema';

/**
 * Given a Schema and an AST node describing a type, return a GraphQLType
 * definition which applies to that type. For example, if provided the parsed
 * AST node for `[User]`, a GraphQLList instance will be returned, containing
 * the type called "User" found in the schema. If a type called "User" is not
 * found in the schema, then undefined will be returned.
 */
/* eslint-disable no-redeclare */
declare function typeFromAST(
  schema: GraphQLSchema,
  typeNode: NamedTypeNode,
): GraphQLNamedType | void;
declare function typeFromAST(
  schema: GraphQLSchema,
  typeNode: ListTypeNode,
): GraphQLList<any> | void;
declare function typeFromAST(
  schema: GraphQLSchema,
  typeNode: NonNullTypeNode,
): GraphQLNonNull<any> | void;
export function typeFromAST(schema, typeNode) {
  /* eslint-enable no-redeclare */
  let innerType;
  if (typeNode.kind === Kind.LIST_TYPE) {
    innerType = typeFromAST(schema, typeNode.type);
    return innerType && GraphQLList(innerType);
  }
  if (typeNode.kind === Kind.NON_NULL_TYPE) {
    innerType = typeFromAST(schema, typeNode.type);
    return innerType && GraphQLNonNull(innerType);
  }
  if (typeNode.kind === Kind.NAMED_TYPE) {
    return schema.getType(typeNode.name.value);
  }

  // Not reachable. All possible type nodes have been considered.
  /* istanbul ignore next */
  throw new Error(`Unexpected type node: "${inspect((typeNode: empty))}".`);
}