graphql/validation/rules/UniqueEnumValueNames.js.flow

A Query Language and Runtime which can target any service.

/**
 * Copyright (c) 2018-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict
 */

import type { SDLValidationContext } from '../ValidationContext';
import { GraphQLError } from '../../error/GraphQLError';
import type { ASTVisitor } from '../../language/visitor';
import { isEnumType } from '../../type/definition';

export function duplicateEnumValueNameMessage(
  typeName: string,
  valueName: string,
): string {
  return `Enum value "${typeName}.${valueName}" can only be defined once.`;
}

export function existedEnumValueNameMessage(
  typeName: string,
  valueName: string,
): string {
  return (
    `Enum value "${typeName}.${valueName}" already exists in the schema. ` +
    'It cannot also be defined in this type extension.'
  );
}

/**
 * Unique enum value names
 *
 * A GraphQL enum type is only valid if all its values are uniquely named.
 */
export function UniqueEnumValueNames(
  context: SDLValidationContext,
): ASTVisitor {
  const schema = context.getSchema();
  const existingTypeMap = schema ? schema.getTypeMap() : Object.create(null);
  const knownValueNames = Object.create(null);

  return {
    EnumTypeDefinition: checkValueUniqueness,
    EnumTypeExtension: checkValueUniqueness,
  };

  function checkValueUniqueness(node) {
    const typeName = node.name.value;

    if (!knownValueNames[typeName]) {
      knownValueNames[typeName] = Object.create(null);
    }

    const valueNames = knownValueNames[typeName];
    if (node.values) {
      for (const valueDef of node.values) {
        const valueName = valueDef.name.value;

        const existingType = existingTypeMap[typeName];
        if (isEnumType(existingType) && existingType.getValue(valueName)) {
          context.reportError(
            new GraphQLError(
              existedEnumValueNameMessage(typeName, valueName),
              valueDef.name,
            ),
          );
          continue;
        }

        if (valueNames[valueName]) {
          context.reportError(
            new GraphQLError(
              duplicateEnumValueNameMessage(typeName, valueName),
              [valueNames[valueName], valueDef.name],
            ),
          );
        } else {
          valueNames[valueName] = valueDef.name;
        }
      }
    }

    return false;
  }
}