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An alternative to working with hexidecimal representations of ObjectId's in mongo.
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Mongo Base64Id - Shell Enhancement

An alternative to working with hexadecimal representations of ObjectId's in mongo.



Instead of:


That is 16 characters instead of 24 and depending on your style, you may prefer it.


After designing an API that looks something like this:


I wondered if there was a more elegant alternative - surely a hexadecimal string is not the most compact form.

MongoDB is a great database and provides a default index field "_id" which is comprised of 12 bytes of data in a type called ObjectID, usually represented in hexadecimal format as above.

There are advantages to sticking with ObjectID, for example:

  1. A high chance of being unique when created.
  2. It includes a timestamp, so no need to create a date created field.


Encoding the 12 ObjectId bytes into URL safe Base64 is simple and effective, meaning you can indeed write an API like this without losing the benefits of ObjectID and all without declaring another field on your document.


But what about the mongo shell? There's clearly no point of having all this indirection if the tools we have refuse to work for us.


Link mongo-base64id.js to .mongorc.js in your home directory.

ln -sf <mongo-base64id-dir>/mongo-base64id.js ~/.mongorc.js

Data is now returned in Base64Id format:

$ mongo
> db.users.find()
{ "_id" : Base64Id("UKZBAooUfVcAYOfa"), "email" : "" }

You can also query by Base64Id:

> db.users.find(Base64Id("UKZBAooUfVcAYOfa"))
{ "_id" : Base64Id("UKZBAooUfVcAYOfa"), "email" : "" }

What if I want to use ObjectId again? Easy:

> setBase64Id(false)

Copyright and Licence

Copyright 2012 Alex Jarvis

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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