Initialisation

Added the packages and files for the backend server

node_modules/graphql/validation/rules/UniqueVariableNamesRule.js

@@ -0,0 +1,49 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', {
+  value: true,
+});
+exports.UniqueVariableNamesRule = UniqueVariableNamesRule;
+
+var _groupBy = require('../../jsutils/groupBy.js');
+
+var _GraphQLError = require('../../error/GraphQLError.js');
+
+/**
+ * Unique variable names
+ *
+ * A GraphQL operation is only valid if all its variables are uniquely named.
+ */
+function UniqueVariableNamesRule(context) {
+  return {
+    OperationDefinition(operationNode) {
+      var _operationNode$variab;
+
+      // See: https://github.com/graphql/graphql-js/issues/2203
+
+      /* c8 ignore next */
+      const variableDefinitions =
+        (_operationNode$variab = operationNode.variableDefinitions) !== null &&
+        _operationNode$variab !== void 0
+          ? _operationNode$variab
+          : [];
+      const seenVariableDefinitions = (0, _groupBy.groupBy)(
+        variableDefinitions,
+        (node) => node.variable.name.value,
+      );
+
+      for (const [variableName, variableNodes] of seenVariableDefinitions) {
+        if (variableNodes.length > 1) {
+          context.reportError(
+            new _GraphQLError.GraphQLError(
+              `There can be only one variable named "$${variableName}".`,
+              {
+                nodes: variableNodes.map((node) => node.variable.name),
+              },
+            ),
+          );
+        }
+      }
+    },
+  };
+}