Initialisation

Added the packages and files for the backend server

node_modules/graphql/validation/rules/UniqueInputFieldNamesRule.js

@@ -0,0 +1,54 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', {
+  value: true,
+});
+exports.UniqueInputFieldNamesRule = UniqueInputFieldNamesRule;
+
+var _invariant = require('../../jsutils/invariant.js');
+
+var _GraphQLError = require('../../error/GraphQLError.js');
+
+/**
+ * Unique input field names
+ *
+ * A GraphQL input object value is only valid if all supplied fields are
+ * uniquely named.
+ *
+ * See https://spec.graphql.org/draft/#sec-Input-Object-Field-Uniqueness
+ */
+function UniqueInputFieldNamesRule(context) {
+  const knownNameStack = [];
+  let knownNames = Object.create(null);
+  return {
+    ObjectValue: {
+      enter() {
+        knownNameStack.push(knownNames);
+        knownNames = Object.create(null);
+      },
+
+      leave() {
+        const prevKnownNames = knownNameStack.pop();
+        prevKnownNames || (0, _invariant.invariant)(false);
+        knownNames = prevKnownNames;
+      },
+    },
+
+    ObjectField(node) {
+      const fieldName = node.name.value;
+
+      if (knownNames[fieldName]) {
+        context.reportError(
+          new _GraphQLError.GraphQLError(
+            `There can be only one input field named "${fieldName}".`,
+            {
+              nodes: [knownNames[fieldName], node.name],
+            },
+          ),
+        );
+      } else {
+        knownNames[fieldName] = node.name;
+      }
+    },
+  };
+}