filter empty selections sets in FilterToSchema (#826)

CHANGELOG.md

@@ -9,6 +9,7 @@
 * Add null to return type of directive visitors in the TypeScript definition.
 * Make sure mergeSchemas keeps Enum descriptions and deprecation status. [PR 898](https://github.com/apollographql/graphql-tools/pull/898/)
 * Add `inheritResolversFromInterfaces` option to `mergeSchemas` [PR #812](https://github.com/apollographql/graphql-tools/pull/812)
+* Added filtering of empty selection sets in FilterToSchema [#827](https://github.com/apollographql/graphql-tools/pull/827)
 
 ### v3.0.5
 

src/test/testTransforms.ts

@@ -7,6 +7,8 @@ import {
   graphql,
   Kind,
   SelectionSetNode,
+  print,
+  parse,
 } from 'graphql';
 import { makeExecutableSchema } from '../makeExecutableSchema';
 import { propertySchema, bookingSchema } from './testingSchemas';
@@ -17,6 +19,7 @@ import {
   FilterTypes,
   WrapQuery,
   ExtractField,
+  FilterToSchema,
 } from '../transforms';
 
 describe('transforms', () => {
@@ -143,6 +146,104 @@ describe('transforms', () => {
     });
   });
 
+  describe('filter to schema', () => {
+    let filter: FilterToSchema;
+    before(() => {
+      filter = new FilterToSchema(bookingSchema);
+    });
+
+    it('should remove empty selection sets on objects', async () => {
+      const query = parse(`
+      query customerQuery($id: ID!) {
+        customerById(id: $id) {
+          id
+          name
+          address {
+            planet
+          }
+        }
+      }
+      `);
+      const filteredQuery = filter.transformRequest({
+        document: query,
+        variables: {
+          id: 'c1'
+        }
+      });
+
+      const expected = parse(`
+      query customerQuery($id: ID!) {
+        customerById(id: $id) {
+          id
+          name
+        }
+      }
+      `);
+      expect(print(filteredQuery.document)).to.equal(print(expected));
+    });
+
+    it('should also remove variables when removing empty selection sets', async () => {
+      const query = parse(`
+      query customerQuery($id: ID!, $limit: Int) {
+        customerById(id: $id) {
+          id
+          name
+          bookings(limit: $limit) {
+            paid
+          }
+        }
+      }
+      `);
+      const filteredQuery = filter.transformRequest({
+        document: query,
+        variables: {
+          id: 'c1',
+          limit: 10
+        }
+      });
+
+      const expected = parse(`
+      query customerQuery($id: ID!) {
+        customerById(id: $id) {
+          id
+          name
+        }
+      }
+      `);
+      expect(print(filteredQuery.document)).to.equal(print(expected));
+    });
+
+    it('should remove empty selection sets on wrapped objects (non-nullable/lists)', async () => {
+      const query = parse(`
+      query bookingQuery($id: ID!) {
+        bookingById(id: $id) {
+          id
+          propertyId
+          customer {
+            favoriteFood
+          }
+        }
+      }
+      `);
+      const filteredQuery = filter.transformRequest({
+        document: query,
+        variables: {
+          id: 'b1'
+        }
+      });
+
+      const expected = parse(`
+      query bookingQuery($id: ID!) {
+        bookingById(id: $id) {
+          id
+          propertyId
+        }
+      }
+      `);
+      expect(print(filteredQuery.document)).to.equal(print(expected));
+    });
+  });
+
   describe('filter type', () => {
     let schema: GraphQLSchema;
     before(() => {

src/transforms/FilterToSchema.ts

@@ -50,9 +50,9 @@ function filterDocumentToSchema(
 ): DocumentNode {
   const operations: Array<
     OperationDefinitionNode
-  > = document.definitions.filter(
-    def => def.kind === Kind.OPERATION_DEFINITION,
-  ) as Array<OperationDefinitionNode>;
+    > = document.definitions.filter(
+      def => def.kind === Kind.OPERATION_DEFINITION,
+    ) as Array<OperationDefinitionNode>;
   const fragments: Array<FragmentDefinitionNode> = document.definitions.filter(
     def => def.kind === Kind.FRAGMENT_DEFINITION,
   ) as Array<FragmentDefinitionNode>;
@@ -95,8 +95,9 @@ function filterDocumentToSchema(
       targetSchema,
       type,
       validFragmentsWithType,
-      operation.selectionSet,
+      operation.selectionSet
     );
+
     usedFragments = union(usedFragments, operationUsedFragments);
 
     const {
@@ -164,7 +165,7 @@ function collectFragmentVariables(
         type,
         validFragmentsWithType,
         fragment.selectionSet,
-      );
+        );
       usedFragments = union(usedFragments, fragmentUsedFragments);
       usedVariables = union(usedVariables, fragmentUsedVariables);
 
@@ -241,8 +242,28 @@ function filterSelectionSet(
           typeStack.push(TypeNameMetaFieldDef.type);
         }
       },
-      leave() {
-        typeStack.pop();
+      leave(node: FieldNode): null | undefined | FieldNode {
+        const currentType = typeStack.pop();
+        const resolvedType = resolveType(currentType);
+        if (
+          resolvedType instanceof GraphQLObjectType ||
+          resolvedType instanceof GraphQLInterfaceType
+        ) {
+          const selections = node.selectionSet && node.selectionSet.selections || null;
+          if (!selections || selections.length === 0) {
+            // need to remove any added variables. Is there a better way to do this?
+            visit(node, {
+              [Kind.VARIABLE](variableNode: VariableNode) {
+                const index = usedVariables.indexOf(variableNode.name.value);
+                if (index !== -1) {
+                  usedVariables.splice(index, 1);
+                }
+              }
+            }
+            );
+            return null;
+          }
+        }
       },
     },
     [Kind.FRAGMENT_SPREAD](node: FragmentSpreadNode): null | undefined {