Initialisation

Added the packages and files for the backend server

node_modules/graphql/validation/rules/UniqueFragmentNamesRule.mjs

@@ -0,0 +1,34 @@
+import { GraphQLError } from '../../error/GraphQLError.mjs';
+
+/**
+ * Unique fragment names
+ *
+ * A GraphQL document is only valid if all defined fragments have unique names.
+ *
+ * See https://spec.graphql.org/draft/#sec-Fragment-Name-Uniqueness
+ */
+export function UniqueFragmentNamesRule(context) {
+  const knownFragmentNames = Object.create(null);
+  return {
+    OperationDefinition: () => false,
+
+    FragmentDefinition(node) {
+      const fragmentName = node.name.value;
+
+      if (knownFragmentNames[fragmentName]) {
+        context.reportError(
+          new GraphQLError(
+            `There can be only one fragment named "${fragmentName}".`,
+            {
+              nodes: [knownFragmentNames[fragmentName], node.name],
+            },
+          ),
+        );
+      } else {
+        knownFragmentNames[fragmentName] = node.name;
+      }
+
+      return false;
+    },
+  };
+}