Mongo.jl

MongoDB bindings for The Julia Language

License

This software is licensed under the simplified BSD license; see the file LICENSE for details.

Installing

Building this package should build and/or install the MongoDB C driver for you.

Setup

You must have a MongoDB server running somewhere. You can specify the host and port in the MongoClient constructor, otherwise it uses the Mongo default locahost:27017.

using Mongo, LibBSON

# Create a client connection
client = MongoClient() # default locahost:27017

# Get a handle to collection named "cats" in database "db".
# Client object, database name, and collection name are stored as variables.
cats = MongoCollection(client, "db", "cats")

# Insert a document
# Mokie is a pretty old cat
m_oid = insert(cats, Dict("name" => "Mokie", "age" => 17))

Dictionary Syntax

With MongoDB, documents and queries are represented as BSONObject structures. In Julia, we can create these from Associative data structures like Dict. However, most functions in this package also accept a Union{Pair,Tuple} in lieu of that, allowing us to omit the Dict constructor:

# Pebbles is an even older cat
p_oid = insert(cats, ("name" => "Pebbles", "age" => 19))

# Ensure they were inserted by counting
println(count(cats, ("name" => "Mokie"))) # 1
println(count(cats)) # 2

Query Syntax

MongoDB queries are also BSON documents, and can include certain modifiers and operators which allow for the construction of complex queries. This package includes shortcut functions for many of them so, for instance instead of typing:

Dict("\$query" => Dict("age" => Dict("\$lt" => 19)))

We can do the following:

# Print all cats under age 19
for doc in find(cats, query("age" => lt(19)))
    println("$(doc["name"]) is younger than 19")
end

Operators and modifiers can be combined by encasing them in parenthesis.

# It's Mokie's birthday!
# We can use the shortcut for the "$inc" operator to increase Mokie's age by 1
update(cats, ("_id" => m_oid), inc("age" => 1))

for doc in find(cats, (query(), orderby("age" => 1)))
    println("$(doc["name"]) is $(doc["age"]) years old.")
end

# Delete the document and ensure it is no more by counting
delete(cats, ("_id" => m_oid))
println(count(cats, ("name" => "Mokie")))

Command Syntax

The command_simple function allows broad access to MongoDB actions. For example, creating an index:

command_simple(client,
               "db",
               Dict(
                  "createIndexes" => "cats",
                  "indexes" => [
                      Dict(
                          "key" => Dict("name" => 1),
                          "name" => "cats_name",
                          "unique" => 1)
                      ]
                  ))

command_simple returns a BSONObject reply, so you can also perform aggregations:

command_simple(client,
               "db",
               OrderedDict(
                  "aggregate" => "cats",
                  "pipeline" => [
                      Dict("\$match" => Dict("age" => 19)),
                      Dict("\$group" => Dict("_id" => "\$name", "count" => Dict("\$sum" => 1)))
                  ]
                )
              )

Refer to the MongoDB database commands docs for further commands.

Contributing

Contributions are welcome! Please fork on github.com and submit a pull request if you have a contribution you think is worthwhile!