| /** @category Validation Rules */ |
| import { GraphQLError } from '../../error/GraphQLError.mjs'; |
| |
| /** |
| * Unique fragment names |
| * |
| * A GraphQL document is only valid if all defined fragments have unique names. |
| * |
| * See https://spec.graphql.org/draft/#sec-Fragment-Name-Uniqueness |
| * @param context - The validation context used while checking the document. |
| * @returns A visitor that reports validation errors for this rule. |
| * @example |
| * ```ts |
| * import { buildSchema, parse, validate } from 'graphql'; |
| * import { UniqueFragmentNamesRule } from 'graphql/validation'; |
| * |
| * const schema = buildSchema(` |
| * type Query { |
| * name: String |
| * } |
| * `); |
| * |
| * const invalidDocument = parse(` |
| * fragment A on Query { name } fragment A on Query { name } query { ...A } |
| * `); |
| * const invalidErrors = validate(schema, invalidDocument, [UniqueFragmentNamesRule]); |
| * |
| * invalidErrors.length; // => 1 |
| * |
| * const validDocument = parse(` |
| * fragment A on Query { name } query { ...A } |
| * `); |
| * const validErrors = validate(schema, validDocument, [UniqueFragmentNamesRule]); |
| * |
| * validErrors; // => [] |
| * ``` |
| */ |
| export function UniqueFragmentNamesRule(context) { |
| const knownFragmentNames = Object.create(null); |
| return { |
| OperationDefinition: () => false, |
| |
| FragmentDefinition(node) { |
| const fragmentName = node.name.value; |
| |
| if (knownFragmentNames[fragmentName]) { |
| context.reportError( |
| new GraphQLError( |
| `There can be only one fragment named "${fragmentName}".`, |
| { |
| nodes: [knownFragmentNames[fragmentName], node.name], |
| }, |
| ), |
| ); |
| } else { |
| knownFragmentNames[fragmentName] = node.name; |
| } |
| |
| return false; |
| }, |
| }; |
| } |