import { GraphQLError } from '../../../error/GraphQLError' ; import type { FieldNode } from '../../../language/ast' ; import type { ASTVisitor } from '../../../language/visitor' ; import { getNamedType } from '../../../type/definition' ; import { isIntrospectionType } from '../../../type/introspection' ; import type { ValidationContext } from '../../ValidationContext' ; /**
 * Prohibit introspection queries
 *
 * A GraphQL document is only valid if all fields selected are not fields that
 * return an introspection type.
 *
 * Note: This rule is optional and is not part of the Validation section of the
 * GraphQL Specification. This rule effectively disables introspection, which
 * does not reflect best practices and should only be done if absolutely necessary.
 */ export function NoSchemaIntrospectionCustomRule ( context ) { return { Field ( node ) { const type = getNamedType ( context . getType ( ) ) ; if ( type && isIntrospectionType ( type ) ) { context . reportError ( new GraphQLError ( `GraphQL introspection has been disabled, but the requested query contained the field "${ node . name . value }".` , node ) ) ; } } , } ; }