Adds support for removing a field on a particular type

src/test/testTransforms.ts

@@ -22,6 +22,7 @@ import {
   ReplaceFieldWithFragment,
   FilterToSchema,
 } from '../transforms';
+import RemoveFieldsOnType from '../transforms/RemoveFieldsOnType';
 
 describe('transforms', () => {
   describe('rename type', () => {
@@ -309,6 +310,34 @@ describe('transforms', () => {
     });
   });
 
+  describe('removing fields from a type', () => {
+    it('removes a field from an existing type', async () => {
+      const newSchema = transformSchema(propertySchema, [
+          new RemoveFieldsOnType('Property', ['name', 'location'])
+      ]);
+      const result = await graphql(
+        newSchema,
+        `
+          query {
+            propertyById(id: "p1") {
+              id
+              name
+              location
+            }
+          }
+        `,
+      );
+      expect(result.errors).not.to.be.empty;
+      expect(result.errors.length).to.equal(2);
+      expect(result.errors[0].message).to.equal(
+        'Cannot query field "name" on type "Property".'
+      );
+      expect(result.errors[1].message).to.equal(
+        'Cannot query field "location" on type "Property".'
+      );
+    });
+  });
+
   describe('tree operations', () => {
     let data: any;
     let subSchema: GraphQLSchema;

src/transforms/AddArgumentsAsVariables.ts

@@ -180,7 +180,7 @@ function typeToAst(type: GraphQLInputType): TypeNode {
         type: innerType,
       };
     } else {
-      throw new Error('Incorrent inner non-null type');
+      throw new Error('Incorrect inner non-null type');
     }
   } else if (type instanceof GraphQLList) {
     return {

src/transforms/ConvertEnumValues.ts

@@ -2,7 +2,7 @@ import { GraphQLSchema, GraphQLEnumType } from 'graphql';
 import { Transform } from '../transforms/transforms';
 import { visitSchema, VisitSchemaKind } from '../transforms/visitSchema';
 
-// Transformation used to modifiy `GraphQLEnumType` values in a schema.
+// Transformation used to modify `GraphQLEnumType` values in a schema.
 export default class ConvertEnumValues implements Transform {
   // Maps current enum values to their new values.
   // e.g. { Color: { 'RED': '#EA3232' } }

src/transforms/RemoveFieldsOnType.ts

@@ -0,0 +1,52 @@
+import {
+  GraphQLObjectType,
+  GraphQLSchema,
+  GraphQLNamedType,
+} from 'graphql';
+import { Transform } from './transforms';
+import { visitSchema, VisitSchemaKind } from './visitSchema';
+import { fieldToFieldConfig, createResolveType } from '../stitching/schemaRecreation';
+
+export default class RemoveFieldsOnType implements Transform {
+  private typeName: string;
+  private fields: Array<string>;
+
+  constructor(typeName: string, fields: Array<string> ) {
+    this.typeName = typeName;
+    this.fields = fields;
+  }
+
+  public transformSchema(originalSchema: GraphQLSchema): GraphQLSchema {
+    return visitSchema(originalSchema, {
+      [VisitSchemaKind.OBJECT_TYPE]: (type: GraphQLObjectType) => {
+        // If it's not the object you're looking for, just skip it
+        if (type.name !== this.typeName) {
+          return type;
+        }
+        // It's the class you're after, so re-create the type
+        // and remove the fields that you want to remove
+        const resolveType = createResolveType(
+          (name: string, originalType: GraphQLNamedType): GraphQLNamedType =>
+            originalType,
+        );
+        const newFields = {};
+        const oldFields = type.getFields();
+        Object.keys(oldFields).forEach(fieldName => {
+          if (!this.fields.includes(fieldName)) {
+            const field = oldFields[fieldName];
+            newFields[fieldName] = fieldToFieldConfig(field, resolveType, true);
+          }
+        });
+        return new GraphQLObjectType({
+          name: type.name,
+          description: type.description,
+          astNode: type.astNode,
+          // extensionASTNodes: type.extensionASTNodes,
+          // interfaces: type.getInterfaces(),
+          // isTypeOf: type.isTypeOf,
+          fields: newFields
+        });
+      },
+    });
+  }
+}