| /** @category Validation Rules */ |
| import type { ASTVisitor } from '../../language/visitor'; |
| import type { ValidationContext } from '../ValidationContext'; |
| /** |
| * Subscriptions must only include a non-introspection field. |
| * |
| * A GraphQL subscription is valid only if it contains a single root field and |
| * that root field is not an introspection field. |
| * |
| * See https://spec.graphql.org/draft/#sec-Single-root-field |
| * @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 { SingleFieldSubscriptionsRule } from 'graphql/validation'; |
| * |
| * const schema = buildSchema(` |
| * type Query { |
| * name: String |
| * } |
| * |
| * type Subscription { |
| * a: String |
| * b: String |
| * } |
| * `); |
| * |
| * const invalidDocument = parse(` |
| * subscription { a b } |
| * `); |
| * const invalidErrors = validate(schema, invalidDocument, [SingleFieldSubscriptionsRule]); |
| * |
| * invalidErrors.length; // => 1 |
| * |
| * const validDocument = parse(` |
| * subscription { a } |
| * `); |
| * const validErrors = validate(schema, validDocument, [SingleFieldSubscriptionsRule]); |
| * |
| * validErrors; // => [] |
| * ``` |
| */ |
| export declare function SingleFieldSubscriptionsRule( |
| context: ValidationContext, |
| ): ASTVisitor; |