flow like the river

VISUALIZACION/node_modules/graphql/validation/rules/SingleFieldSubscriptionsRule.js

@@ -0,0 +1,25 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.SingleFieldSubscriptionsRule = SingleFieldSubscriptionsRule;
+
+var _GraphQLError = require("../../error/GraphQLError.js");
+
+/**
+ * Subscriptions must only include one field.
+ *
+ * A GraphQL subscription is valid only if it contains a single root field.
+ */
+function SingleFieldSubscriptionsRule(context) {
+  return {
+    OperationDefinition: function OperationDefinition(node) {
+      if (node.operation === 'subscription') {
+        if (node.selectionSet.selections.length !== 1) {
+          context.reportError(new _GraphQLError.GraphQLError(node.name ? "Subscription \"".concat(node.name.value, "\" must select only one top level field.") : 'Anonymous Subscription must select only one top level field.', node.selectionSet.selections.slice(1)));
+        }
+      }
+    }
+  };
+}