Initialisation

Added the packages and files for the backend server

node_modules/graphql/validation/rules/ScalarLeafsRule.js

@@ -0,0 +1,55 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', {
+  value: true,
+});
+exports.ScalarLeafsRule = ScalarLeafsRule;
+
+var _inspect = require('../../jsutils/inspect.js');
+
+var _GraphQLError = require('../../error/GraphQLError.js');
+
+var _definition = require('../../type/definition.js');
+
+/**
+ * Scalar leafs
+ *
+ * A GraphQL document is valid only if all leaf fields (fields without
+ * sub selections) are of scalar or enum types.
+ */
+function ScalarLeafsRule(context) {
+  return {
+    Field(node) {
+      const type = context.getType();
+      const selectionSet = node.selectionSet;
+
+      if (type) {
+        if ((0, _definition.isLeafType)((0, _definition.getNamedType)(type))) {
+          if (selectionSet) {
+            const fieldName = node.name.value;
+            const typeStr = (0, _inspect.inspect)(type);
+            context.reportError(
+              new _GraphQLError.GraphQLError(
+                `Field "${fieldName}" must not have a selection since type "${typeStr}" has no subfields.`,
+                {
+                  nodes: selectionSet,
+                },
+              ),
+            );
+          }
+        } else if (!selectionSet) {
+          const fieldName = node.name.value;
+          const typeStr = (0, _inspect.inspect)(type);
+          context.reportError(
+            new _GraphQLError.GraphQLError(
+              `Field "${fieldName}" of type "${typeStr}" must have a selection of subfields. Did you mean "${fieldName} { ... }"?`,
+              {
+                nodes: node,
+              },
+            ),
+          );
+        }
+      }
+    },
+  };
+}