pod afMongo

A pure Fantom driver for MongoDB



Represents a connection to a MongoDB instance.


Manages connections to a MongoDB instance.



Represents a MongoDB collection.


Manages a pool of connections.


Iterates over database query results.


Represents a MongoDB database.


Represents a MongoDB index.


A MongoDB client.


The low level transport mechanism that talks to MongoDB instances.


Represents a MongoDB user.



As thrown by Mongo.


Mongo is a pure Fantom driver for MongoDB.

Mongo driver features:

  • Compatible with MongoDB v2.6 / 3.x+
  • Standard and capped collections
  • Write commands: insert(), update(), delete() and findAndModify()
  • Write concern support
  • Optimised queries for findOne() and findAll()
  • Cursor support
  • Aggregation commands: aggregate(), distinct(), group() and mapReduce()
  • Index support: create(), ensure() and drop()
  • User support: create(), drop(), grant() and revoke() roles
  • Database authentication
  • Server side eval() commands
  • Pooled connection manager for multi-threaded use
  • Support for Replica Set connection URLs

Mongo driver has been written specifically for MongoDB v2.6.0 or newer.

Many features, including ALL write commands, will NOT work with older MongoDB versions.

ALIEN-AID: See Morphia for a complete Fantom to MongoDB object mapping library!


Install Mongo with the Fantom Repository Manager ( fanr ):

C:\> fanr install -r http://repo.status302.com/fanr/ afMongo

To use in a Fantom project, add a dependency to build.fan:

depends = ["sys 1.0", ..., "afMongo 1.0"]


Full API & fandocs are available on the Status302 repository.

Quick Start

1). Start up an instance of MongoDB:

C:\> mongod

MongoDB starting
db version v2.6.0
waiting for connections on port 27017

2). Create a text file called Example.fan:

using afBson
using afMongo
using concurrent

class Example {

    Void main() {
        mongoClient := MongoClient(ActorPool(), `mongodb://localhost:27017`)
        collection  := mongoClient.db("friends").collection("birds")

        documentIn  := [
            "_id"   : ObjectId(),
            "name"  : "Emma",
            "score" : 9

        echo( collection.findAll.first )


3). Run Example.fan as a Fantom script from the command line:

C:\> fan Example.fan

 _____ ___ ___ ___ ___
|     | . |   | . | . |
|_|_|_|___|_|_|_  |___|

Connected to MongoDB v2.6.5 (at mongodb://localhost:27017)

[_id:5373acbda8000b3491000001, name:Emma, score:9]


MongoClient is the main entry point into Mongo. From there you can access all other components of MongoDB, namely Database, Collection, Index and User.

 `-- Database
      +-- Collection
      |    `-- Index
      `-- User


MongoClient is created with a ConnectionManager, which manages your connections to MongoDB. Use ConnectionManagerPooled for normal multi-threaded use:

conMgr := ConnectionManagerPooled(ActorPool(), `mongodb://localhost:27017`)
client := MongoClient(conMgr)

When you create a MongoClient it immediately connects to MongoDB and verifies the version:

.    Alien-Factory
 _____ ___ ___ ___ ___
|     | . |   | . | . |
|_|_|_|___|_|_|_  |___|

Connected to MongoDB v2.6.5

Note that ConnectionManagerPooled will always query the supplied MongoDB host(s) to find the primary node, on which all read and write operations are performed.


Mongo and MongoDB work with documents, they are used throughout the Mongo API. A MongoDB document is represented in Fantom as a Map of type [Str:Obj?]. All document keys must be strings. Document values can be any valid BSON type.

A MongoDB database stores documents in collections. Use the find() methods to query a collection. Using the friends database in the QuickStart Example we could do:

collection.findOne( ["name":"Emma"] )       // --> return the doc where 'name == Emma'
                                            //     ('Emma' must be unique)

collection.findAll                          // --> return ALL docs in the collection
collection.findAll( ["name":"Emma"] )       // --> return all docs where 'name == Emma'
collection.findAll( ["score": ["\$gt":7]] ) // --> return all docs with 'score > 7'

The $gt expression is an example of a Query operator.

To iterate over a massive collection without loading it all into memory, use a Cursor. Cursors download documents in batches, behind the scenes, as and when required. Create and use a Cursors by using the find() method:

collection.find( ["score": ["\$gt":2]] ) |cursor| {
    cursor.batchSize = 10

    while (cursor.hasNext)
        doc := cursor.next

Write Commands

The insert() command is simple enough and is demonstrated in the QuickStart example.

update() and delete() are similar in that they both take a query that describes which document(s) are to be updated / deleted. For most usages this will a simply be the id of the document in question:

collection.update( ["_id": objId], [ ...new doc...] )

Note that as of MongoDB v2.6 there is longer any need to call a getLastError() function. All error handling is done via write concerns. By default Mongo will throw a MongoErr should a write error occur.


All documents held in a collection need a unique id, held in a field named _id. If the _id field does not exist, MongoDB will create one for you of type ObjectId.

Note that _id does not need to an ObjectId, it can be any BSON type. It just needs to be unique in the collection.

Like marmite, people tend to have a love / hate relationship with the ObjectId. The good comments revolve around it having a natural sort that (roughly) corresponds to creation time. The bad is that in humongous collections it eats up precious bytes which means the index can't fit into RAM.


The Alien-Factory MongoDB driver was inspired by fantomongo by Liam Staskawicz.

If you're looking for cross-platform MongoDB GUI client then look no further than Robomongo!

Release Notes


  • New: Updated for MongoDB 3.x.
  • Chg: Added fieldNames parameter to findAll() - see Issue #1.
  • Chg: Made the deleteMulti(), insertMulti() and updateMulti() methods in Collection public.
  • Chg: Documented some options parameters.


  • New: Support for connecting to Replica Sets via multiple hosts in the Mongo connection URL. All read and write operations performed on the primary.
  • New: Support for the waitQueueTimeoutMS Mongo connection URL option with a truncated binary exponential backoff algorithm to wait for available connections.
  • New: Support for write concern options in the Mongo connection URL.
  • New: Support for connectTimeoutMS and socketTimeoutMS Mongo URL connection options.
  • Chg: The default write concern has moved out of MongoClient / Database / Collection / User and into the ConnectionManager.
  • Chg: Cursor.count now takes into account skip and limit.
  • Chg: Renamed ConnectionManager.mongoUri -> ConnectionManager.mongoUrl.
  • Chg: Index keys must be ordered if they contain more than one entry.
  • Chg: Better Err msg if could not connect to MongoDB.
  • Bug: Cursor.count threw an Err if the query was ordered.


  • Bug: Index.ensure() when comparing indexes did not respect unique:false.


  • New: ConnectionManagerPooled instances are created with a Mongo Connection URI.
  • New: ConnectionManagerPooled accepts default database and user credentails to initially authenticate all leased connections with.


  • New: Preview Release