Clear data loader cache correctly (#46)

* Clear data loader cache correctly, fixes #44
* Add to DataLoader test

Co-authored-by: Loren 🤓 <lorensr@gmail.com>

Author: 9at8

src/__tests__/cache.test.js

@@ -7,8 +7,7 @@ import { createCachingMethods, idToString } from '../cache'
 
 const docs = {
   id1: {
-    _id: 'id1'
-    // _id: ObjectId()
+    _id: 'aaaa0000bbbb0000cccc0000'
   },
   id2: {
     _id: ObjectId()
@@ -32,7 +31,15 @@ describe('createCachingMethods', () => {
             setTimeout(
               () =>
                 resolve(
-                  ids.map(id => (id === docs.id1._id ? docs.id1 : docs.id2))
+                  ids.map(id => {
+                    if (id.equals(new ObjectId(docs.id1._id))) {
+                      return docs.id1
+                    }
+
+                    if (id.equals(docs.id2._id)) {
+                      return docs.id2
+                    }
+                  })
                 ),
               0
             )
@@ -111,4 +118,19 @@ describe('createCachingMethods', () => {
       expect(valueAfter).toBeUndefined()
     }
   })
+
+  it('deletes from DataLoader cache', async () => {
+    for (const id of [docs.id1._id, docs.id2._id]) {
+      await api.findOneById(id)
+      expect(collection.find).toHaveBeenCalled()
+      collection.find.mockClear()
+
+      await api.findOneById(id)
+      expect(collection.find).not.toHaveBeenCalled()
+
+      await api.deleteFromCacheById(id)
+      await api.findOneById(id)
+      expect(collection.find).toHaveBeenCalled()
+    }
+  })
 })

src/cache.js

@@ -5,6 +5,7 @@ import { EJSON } from 'bson'
 import { getCollection } from './helpers'
 
 export const idToString = id => (id instanceof ObjectId ? id.toHexString() : id)
+const stringToId = str => str instanceof ObjectId ? str : new ObjectId(str)
 
 // https://github.com/graphql/dataloader#batch-function
 const orderDocs = ids => docs => {
@@ -19,7 +20,7 @@ export const createCachingMethods = ({ collection, model, cache }) => {
   const loader = new DataLoader(ids => {
     const filter = {
       _id: {
-        $in: ids
+        $in: ids.map(stringToId)
       }
     }
     const promise = model
@@ -40,7 +41,7 @@ export const createCachingMethods = ({ collection, model, cache }) => {
         return EJSON.parse(cacheDoc)
       }
 
-      const doc = await loader.load(id)
+      const doc = await loader.load(idToString(id))
       if (Number.isInteger(ttl)) {
         // https://github.com/apollographql/apollo-server/tree/master/packages/apollo-server-caching#apollo-server-caching
         cache.set(key, EJSON.stringify(doc), { ttl })