Adds conditional check on mongoose

- Using .lean() and not .toArray() on queries when mongoose

Author: emilmork

src/cache.js

@@ -1,17 +1,26 @@
 import DataLoader from 'dataloader'
 
+const remapDocs = (docs, ids) => {
+  const idMap = {}
+  docs.forEach(doc => {
+    idMap[doc._id] = doc
+  })
+  return ids.map(id => idMap[id])
+}
+
 export const createCachingMethods = ({ collection, cache }) => {
+  const isMongoose = typeof collection === 'function'
+
   const loader = new DataLoader(ids =>
-    collection
-      .find({ _id: { $in: ids } })
-      .toArray()
-      .then(docs => {
-        const idMap = {}
-        docs.forEach(doc => {
-          idMap[doc._id] = doc
-        })
-        return ids.map(id => idMap[id])
-      })
+    isMongoose
+      ? collection
+          .find({ _id: { $in: ids } })
+          .lean()
+          .then(docs => remapDocs(docs, ids))
+      : collection
+          .find({ _id: { $in: ids } })
+          .toArray()
+          .then(docs => remapDocs(docs, ids))
   )
 
   const cachePrefix = `mongo-${collection.collectionName}-`