Saving data to a MongoDB database

MongoDB can very naturally store unstructured data using the JSON syntax. In this recipe, we will store a list of people to MongoDB.

Getting ready

We must first install MongoDB on our machine. The installation files can be downloaded from http://www.mongodb.org.

We need to make a directory for the database using the following command:

$ mkdir ~/db

Finally, start the MongoDB daemon on that directory using the following command:

$ mongod –dbpath ~/db

Install the MongoDB package from cabal using the following command:

$ cabal install mongoDB

How to do it…

Create a new file called Main.hs and perform the following steps:

1. Import the libraries as follows:

   {-# LANGUAGE OverloadedStrings, ExtendedDefaultRules #-}
   import Database.MongoDB
   import Control.Monad.Trans (liftIO)

2. Define a data type for the names of people as follows:

   data Person = Person { first :: String 
                        , last :: String }

3. Set up a couple of data items we wish to store as follows...