Compare Two MongoDB Collections (even on different servers) in TypeScript

mongodb-diff.ts

/**
 * MIT License
 * Copyright (c) 2023 Cody Sand 
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * 
 * 
 * This script compares two MongoDB collections and reports any differences. 
 * 
 * Credit for the workflow goes to @niccottrell (https://github.com/niccottrell)
 * Original: https://gist.github.com/niccottrell/3ff2efc2146090aa8c5b73c1eb75ba2c
 * 
 * This version uses the node `mongodb` package instead of the internal mongodb script engine. 
 *
 * To launch and debug this inside of VSCode, use the "Run Script" launch configuration below
 *
 * {
 *  "name": "DB Diff",
 *  "type": "node",
 *  "request": "launch",
 *  "runtimeArgs": ["-r", "${workspaceFolder}/node_modules/ts-node/register/transpile-only"],
 *  "args": ["${workspaceFolder}/path/to/this/file//db-diff.ts"],
 *  "console": "integratedTerminal"
 * }
 */
import { MongoClient } from "mongodb";

const runScript = async () => {
  const uriOld =
    "mongodb+srv://user:password@mongo.example.com";
  const uriNew =
    "mongodb+srv://user:password@mongo.example.com";
  const dbNameOld = "old_db";
  const dbNameNew = "new_db";

  // connect to mongos
  const connOld = await MongoClient.connect(uriOld);
  const dbOld = connOld.db(dbNameOld);

  const connNew = await MongoClient.connect(uriNew);
  const dbNew = connNew.db(dbNameNew);

  var collectionsToCheck = ["media"];

  const oldCollections = await dbOld.collections();
  oldCollections.forEach(async function (collname) {
    const collectionName = collname.collectionName;
    if (collectionsToCheck.includes(collectionName)) {
      console.log("Checking " + collectionName);
      // Check count and size first
      const cstatsOld = await dbOld.command({ collStats: collectionName });
      const cstatsNew = await dbNew.command({ collStats: collectionName });
      if (cstatsOld.count === cstatsNew.count) {
        console.log("Count " + cstatsOld.count + " OK");
      } else {
        console.log(
          "ERR Count mismatch " + cstatsOld.count + " -> " + cstatsNew.count
        );
      }
      if (cstatsOld.size === cstatsNew.size) {
        console.log("Size " + cstatsOld.size + " OK");
      } else {
        console.log(
          "ERR Size mismatch " + cstatsOld.size + " -> " + cstatsNew.size
        );
      }

      let fails = 0;
      const oldRecords = await dbOld
        .collection(collectionName)
        .find({})
        .toArray();

      await Promise.all(
        oldRecords.map(async (docOld) => {
          const docNew = await dbNew.collection(collectionName).findOne({
            _id: docOld._id,
          });
          const stringOld = JSON.stringify(docOld);
          const stringNew = JSON.stringify(docNew);
          if (stringOld == stringNew) {
            // console.log("Doc matches: " + docOld._id);
          } else {
            console.log("Doc mismatch: " + docOld._id);
            //   console.log("Old=", docOld);
            //   console.log("New=", docNew);
            fails++;
          }
        })
      );

      if (fails > 0) {
        console.log(fails + " fails");
      } else {
        console.log("All OK");
      }

      connOld.close();
      connNew.close();
      process.exit(0);
    }
  });
};

runScript();