MongoDB Shell Enhancements for Hackers
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MongoDB Shell Enhancements


  • These enhancements are useful to me but they don't make sense for everyone. Feel free to tweak to your desire and please submit feedback or pull requests.
  • Does not work with mongo shell or MongoDB servers < 2.4
  • Updates called on existing cursors are new and experimental (see notes in API section)


Install as a global module from npm:

npm install -g mongo-hacker

Clone the repository and install with make

Clone this repository, cd into it, and run make install. This will rename your existing .mongorc.js file to .mongorc.js.orig and link mongo_hacker.js to .mongorc.js in your home directory:

git clone --depth=1
rm -rf ~/.mongorc.js # may be needed as we don't force the link anymore
cd mongo-hacker
make install


Basic UX

  • Sort document keys by default
  • Highlight querytime if verboseShell is enabled
    • In green if querytime is at or below slowms
    • In red if query time is above slowms
  • Default indent is 2 spaces instead of tab
    • Customizable by setting indent key of config
  • Verbose shell is enabled by default -- to disable: setVerboseShell(false)
  • Disable notfication of "Type 'it' for more"
  • Custom prompt: hostname(process-version)[rs_status:set_name] db>
  • Always pretty print. You can still use default format by appending .ugly() to the end of db statement.
  • Show DBs has aligned columns and shows less significant digits (in master for Mongo 2.5/2.6)
  • Nicer sh.status() output (remove lastmod, take up less space, colorize chunk's shard)


Colorized query output for console/terminal windows supporting ANSI color codes.

Colorized Output

Additional shell commands

The MongoDB shell offers various "shell commands" (sometimes referred to as "shell helpers" as well) that make interactive use of the shell much more convenient than proper, Javascript-only scripted use of the shell.

To make interactive use of the MongoDB shell even more convenient, mongo-hacker adds the following shell commands:

  • count collections/count tables: count the number of collections in each of the mongo server's databases - by @pvdb
  • count documents/count docs: count the number of documents in all (non-system) collections in the database - by @pvdb

API Additions


Get a list of database names: (by @pvdb)


(note that this method is similar - functionality-wise and usage-wise - to the existing db.getCollectionNames() API method and allows for advanced, cross-database scripting in the MongoDB shell)


Filter for a collection of documents:


One for finding a single document:

db.collection.find({ ... }).one() == db.collection.findOne({ ... })

Select for selecting fields to return (projection):

db.collection.find({ ... }).select({ name: 1 })

Reverse for descending sort by insertion order (default) or arbitrary field:

db.collection.find({ ... }).reverse()
db.collection.find({ ... }).reverse('createDate')

Last for finding last inserted document (default) or document last by given field:

db.collection.find({ ... }).last()
db.collection.find({ ... }).last('createDate')

Update, Replace, Upsert and Remove can be called on a DBQuery Object:

db.collection.find({ ... }).update({ ... })  // multi update
db.collection.find({ ... }).replace({ ... }) // single replacement
db.collection.find({ ... }).upsert({ ... })  // single upsert
db.collection.find({ ... }).remove()         // multi remove

Sort, limit, and skip through multi updates and removes:

db.collection.find({ ... }).limit(7).update({ ... })
db.collection.find({ ... }).sort({ ... }).skip(1).limit(3).update({ ... })
db.collection.find({ ... }).limit(3).remove()

Note: The performance of multi updates involving a skip or limit may be worse than those without those specifications due to there being absolutely no native support for this feature in MongoDB itself. It should be understood by the user of this software that use of this feature (by calling update on a cursor rather than a collection) is advanced and experimental. The option to do this sort of operation is purely additive to the MongoDB experience with MongoHacker and usage of it is in no way required. Furthermore, its inclusion in this enhancement does not effect the operation of updates invoked through collections and, in practice, is insanely useful.

Aggregation Framework

The aggregation framework is now fluent as well. You can use it as currently documented or via the chainable methods.

Calling aggregate without an array of operations or $operations will make it a match.

// matches every document

// matches documents where the "a" is equal to 1
db.collection.aggregate({a: 1})

// matches documents where "a" is greater than 7
db.collection.aggregate({a: {$gt: 7}})

Additional methods can then be chained on top of the inital match in order to make more complicated aggregations.

// Match and project
db.collection.aggregate({a: 1}).project({a: 1, _id: 0})

// Match, group and sort
db.test.aggregate().group({_id: '$a', 'sum': {'$sum': 1}}).sort({sum: -1})


General Shell Helpers

  • findCommand('search') list commands that match the search string

Aggregation Framework Helpers -- on collections

  • Group and Count: gcount(group_field, filter)
  • Group and Sum: gsum(group_field, sum_field, filter)
  • Group and Average: gavg(group_field, avg_field, filter)