fix: Always use lean Mongoose documents

index.d.ts

@@ -5,6 +5,7 @@ declare module 'apollo-datasource-mongodb' {
     Collection as MongooseCollection,
     Document,
     Model as MongooseModel,
+    LeanDocument
   } from 'mongoose'
 
   export type Collection<T, U = MongoCollection<T>> = T extends Document
@@ -44,17 +45,17 @@ declare module 'apollo-datasource-mongodb' {
     findOneById(
       id: ObjectId | string,
       options?: Options
-    ): Promise<TData | null | undefined>
+    ): Promise<LeanDocument<TData> | null | undefined>
 
     findManyByIds(
       ids: (ObjectId | string)[],
       options?: Options
-    ): Promise<(TData | null | undefined)[]>
+    ): Promise<(LeanDocument<TData> | null | undefined)[]>
 
     findByFields(
       fields: Fields,
       options?: Options
-    ): Promise<(TData | null | undefined)[]>
+    ): Promise<(LeanDocument<TData> | null | undefined)[]>
 
     deleteFromCacheById(id: ObjectId | string): Promise<void>
     deleteFromCacheByFields(fields: Fields): Promise<void>

src/__tests__/datasource.test.js

@@ -107,7 +107,7 @@ describe('Mongoose', () => {
     users.initialize()
     const user = await users.findOneById(alice._id)
     expect(user.name).toBe('Alice')
-    expect(user.id).toBe(alice._id.toString())
+    expect(user._id.toString()).toBe(alice._id.toString())
   })
 
   test('Data Source with Collection', async () => {

src/cache.js

@@ -135,7 +135,10 @@ export const createCachingMethods = ({ collection, model, cache }) => {
     log('filter: ', filter)
 
     const findPromise = model
-      ? model.find(filter).exec()
+      ? model
+          .find(filter)
+          .lean()
+          .exec()
       : collection.find(filter).toArray()
 
     const results = await findPromise