How to check if a string is valid MongoDB ObjectId in Node.js ?

Checking if a string is valid mongoDB ObjectID is important while working with databases. It ensures accurate reference the the objects in databases. We can validate the ObjectId with the help of isValid function in MongoDB.

Prerequisites:

• NodeJS and NPM installed
• Mongoose and MongoDB

MongoDB ObjectId

MongoDB creates a unique 12 bytes ID for every object using the timestamp of respective Object creation. This ObjectId can be used to uniquely target a specific object in the database.

Structure:

• 4-byte timestamp value
• 5-byte random value
• 3-byte incrementing counter, initialized to a random value

It looks like this,

507f191e810c19729de860ea

How to Check Valid MongoDB ObjectId ?

During a normal backend workflow, the ObjectId might be received based on some computation or use operations. These might result invalid ObjectId and querying databases with the wrong ObjectId gives exception which is then handled later. We can use the ObjectId.isValid function from mongoDB to validate the correct ObjectId.

In this article, we will learn how to check if a string is valid MongoDB ObjectId.

Examples:

594ced02ed345b2b049222c5 --> Valid MongoDB ObjectId
geeks --> Invalid MongoDB ObjectId

Using MongoDB ObjectId.isValid

Mongoose & MongoDB provide a very useful function in ObjectId i.e. ObjectId.isValid("some_id") to validate a string for correct MongoDB ID.
ObjectId can be imported from native mongodb as well as mongoose package.

Import ObjectId

• Using Mongodb:

const ObjectId = require('mongodb').ObjectId;
or
const mongodb, {ObjectId} = require('mongodb');

• Using Mongoose:

const ObjectId = require('mongoose').Types.ObjectId;
or
const mongoose = require('mongoose');
ObjectId = mongoose.Types.ObjectId;Id;

Problem with isValid function

However, it ObjectId.isValid(id) returns true even for invalid strings with length 12.
For example :

Using ObjectId with String typecasting

To prevent such cases, another check can be added after default validator which would return true or false based on condition, (new ObjectId created from string) cast to string === string
i.e. (String)(new ObjectId(id)) === id
A function can be created as follows to check if a string is valid ObjectId or not:

const ObjectId = require('mongoose').Types.ObjectId;
function isValidObjectId(id){
    
    if(ObjectId.isValid(id)){
        if((String)(new ObjectId(id)) === id)
            return true;
        return false;
    }
    return false;
}

// Requiring ObjectId from mongoose npm package
const ObjectId = require('mongoose').Types.ObjectId;

// Validator function
function isValidObjectId(id){
    
    if(ObjectId.isValid(id)){
        if((String)(new ObjectId(id)) === id)
            return true;        
        return false;
    }
    return false;
}

// Loading testcases into array
const testStrings = [ "594ced02ed345b2b049222c5","geeks",  
                      "toptoptoptop","geeksfogeeks"];

// Validating each test case
for(const testcase of testStrings){

    if(isValidObjectId(testcase))
        console.log(testcase + " is a valid MongodbID");
    else
        console.log(testcase + " is not a valid MongodbID");

}

Output: Results of this function are:

Summary

The MongoDB ObjectId can be validate using the ObectId.isValid funtion but it fails in some cases hence typecast the id's to string and then compare for more accurate results.