A Lua driver for MongoDB

Versions compatibility

LuaMongo	mongo-c++-driver
v0.5	legacy-1.1
v0.4	legacy-0.9

LuaMongo v1.0 is expected when the modern c++ driver is marked as stable. See at the end of this file what changes are introduced from v0.4 to v0.5.

Compilation

The makefile automatically detects which platform and Lua version are you using, so for compilation you just need to do:

$ make

You can force the platform compilation by using $ make Linux or $ make Darwin. Additionally, you can force the Lua version by doing:

$ make LUAPKG=lua5.2

where lua5.2 can be replaced by lua5.1 and luajit.

Installation

Copy the library file mongo.so to any of the paths in LUA_CPATH environment variable or Lua string package.path.

Wiki Documentation

• BsonTypes

• HelperFunctions

• GridFS

• GridFileBuilder

• MongoConnection - START HERE

• MongoReplicaSet

• MongoCursor

Support

Submit issues to the moai github site.

There is a Google Groups mailing list.

Example

local mongo = require('mongo')

-- Create a connection object
local db = assert(mongo.Connection.New())

-- connect to the server on localhost
assert(db:connect('localhost'))

-- insert a value into the namespace 'test.values'
assert(db:insert('test.values', {a = 10, b = 'str1'}))

-- the same using a JSON string
assert(db:insert('test.values', "{'a': 20, 'b': 'str2'}"))

-- insert a multiple values into the namespace 'test.values'
assert(db:insert_batch('test.values', {{a = 10, b = 'str1'}, {c = 11, d = 'str2'}}))

-- print the number of rows in the namespace 'test.values'
print(db:count('test.values'))

-- query all the values in the namespace 'test.values'
local q = assert(db:query('test.values', {}))

-- loop through the result set
for result in q:results() do
    print(result.a)
    print(result.b)
end

How It Works

LuaMongo is a Lua library that wraps the MongoDB C++ API. Currently it has been tested with legacy-1.1.0 version of this driver. This mongo-cxx-driver release has been included at external folder, you can download it by executing:

$ git submodule update --init

The current implementation does not give you raw access to the BSON objects. BSON objects are passed to the API using a Lua table or a JSON string representation. Every returned BSON document is fully marshalled to a Lua table.

Installing

luarocks can be used to install LuaMongo last SCM version:

luarocks install "https://raw.githubusercontent.com/moai/luamongo/master/rockspec/luamongo-scm-0.rockspec"

or install any other of the versions available at rockspec directory.

For modern Linux systems, you will need to update your luarocks configuration file, usually located at /etc/luarocks/config.lua or /usr/local/etc/luarocks/config.lua, adding the following Lua table:

external_deps_dirs = {
  {
    prefix='/usr/',
    include='include',
    lib='lib',
  },
  {
    prefix='/usr/',
    include='include',
    lib='lib/i386-linux-gnu',
  },
  {
    prefix='/usr/',
    include='include',
    lib='lib/x86_64-linux-gnu',
  },
  {
    prefix='/usr/local',
  },
}

Changes from v0.4 to v0.5

• GridFileBuilder has been introduced into legacy C++ driver, LuaMongo don't implements it any more. The constructor has been changed and now it only receives an instance of GridFS class.

• db:ensure_index() function has been replaced by db:create_index(). The parameters of the new function are create_index(ns,keys,options) where keys and options can be Lua tables or JSON strings (both dictionaries which allow 'unique' and 'name' fields).

• db:get_indexes() is now db:enumerate_indexes().

• db:reset_index_cache() has been removed.

• gridfs:find_file() requires a query. It has been added gridfs:find_file_by_name(filename) equivalent to old implementation.