From 32d9ed34cc646d17e2e55525e5d4b3ba924d89bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20N=C4=9Bmec?= <michal.nemec.dev@gmail.com>
Date: Wed, 17 Nov 2021 13:18:03 +0100
Subject: [PATCH] Fix insertMany exception when empty array is used

---
 lib/richlist/storage/mongo.js | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/richlist/storage/mongo.js b/lib/richlist/storage/mongo.js
index c944d36..0999979 100644
--- a/lib/richlist/storage/mongo.js
+++ b/lib/richlist/storage/mongo.js
@@ -191,13 +191,22 @@ class MongoStorage {
             }
         }
 
+        const insertManyCollection = (collection, data) => {
+            if(data.length === 0) {
+                return Promise.resolve()
+            }
+            // insertMany fails when data is empty array 
+            // (node:1) UnhandledPromiseRejectionWarning: MongoError: Invalid Operation, no operations specified
+            return collection.insertMany(data)
+        }
+
         // insert documents
-        return this.transactions.insertMany(txs.map(tx => ({
+        return insertManyCollection(this.transactions, txs.map(tx => ({
             hash: tx.hash,
             locktime: tx.locktime,
             version: tx.version
         }))).then(() => {
-            return this.outputs.insertMany(outputs);
+            return insertManyCollection(this.outputs, outputs);
         }).then(() => this.blocks.insertOne({
             hash: block.hash,
             height: block.height,