Use single write instead of bulk

src/api/db/models/Image.js

@@ -369,27 +369,16 @@ export class ImageModel {
   }
 
   static async createComment(input, context) {
-    const operation = async (input) => {
-      return await retry(async (bail, attempt) => {
-        if (attempt > 1) console.log(`Retrying createComment operation! Try #: ${attempt}`);
-
-        // find images, add comment, and bulk write
-        return await Image.bulkWrite([{
-          updateOne: {
-            filter: { _id: input.imageId },
-            update: { $push: { comments: {
-              author: context.user['cognito:username'],
-              comment: input.comment
-            } } }
-          }
-        }]);
-      }, { retries: 2 });
-    };
-
     try {
-      await operation(input);
       const image = await ImageModel.queryById(input.imageId, context);
 
+      if (!image.comments) image.comments = [];
+      image.comments.push({
+        author: context.user['cognito:username'],
+        comment: input.comment
+      });
+      await image.save();
+
       return { comments: image.comments };
     } catch (err) {
       // if error is uncontrolled, throw new ApolloError

src/api/db/schemas/Image.js

@@ -14,7 +14,7 @@ const Schema = mongoose.Schema;
  */
 
 const ImageCommentSchema = new Schema({
-  _id: { type: String, required: true, default: Schema.Types.ObjectId, },
+  _id: { type: String, required: true, default: Schema.Types.ObjectId },
   author: { type: String, required: true },
   created: { type: Date, default: Date.now, required: true },
   comment: { type: String, required: true }