137 lines
2.8 KiB
Markdown
137 lines
2.8 KiB
Markdown
MongoDB Haskell Mini Tutorial
|
|
-----------------------------
|
|
|
|
__Author:__ Brian Gianforcaro (b.gianfo@gmail.com)
|
|
|
|
__Updated:__ 2/28/2010
|
|
|
|
This is a mini tutorial to get you up and going with the basics
|
|
of the Haskell mongoDB drivers. It is modeled after the python tutorial
|
|
pymongo available here: http://api.mongodb.org/python/1.4%2B/tutorial.html
|
|
|
|
You will need the mongoDB bindings installed as well as mongo itself installed.
|
|
|
|
>$ = command line prompt
|
|
> = ghci repl prompt
|
|
|
|
|
|
Installing Haskell Bindings
|
|
---------------------------
|
|
|
|
From Source:
|
|
|
|
> $ git clone git://github.com/srp/mongoDB.git
|
|
|
|
> $ cd mongoDB
|
|
|
|
> $ runhaskell Setup.hs configure
|
|
|
|
> $ runhaskell Setup.hs build
|
|
|
|
> $ runhaskell Setup.hs install
|
|
|
|
From Hackage using cabal:
|
|
|
|
> $ cabal install mongoDB
|
|
|
|
|
|
Getting Ready
|
|
-------------
|
|
|
|
Start a MongoDB instance for us to play with:
|
|
|
|
> $ mongod
|
|
|
|
Start up a haskell repl:
|
|
|
|
> $ ghci
|
|
|
|
Now We'll need to bring in the MongoDB/BSON bindings:
|
|
|
|
> import Database.MongoDB
|
|
|
|
> import Database.MongoDB.BSON
|
|
|
|
Making A Connection
|
|
-------------------
|
|
Open up a connection to your DB instance, using the standard port:
|
|
|
|
> con <- connect "127.0.0.1" []
|
|
|
|
or for a non-standard port
|
|
|
|
> import Network
|
|
> con <- connectOnPort "127.0.0.1" (Network.PortNumber 666) []
|
|
|
|
By default mongoDB will try to find the master and connect to it and
|
|
will throw an exception if a master can not be found to connect
|
|
to. You can force mongoDB to connect to the slave by adding SlaveOK as
|
|
a connection option, eg:
|
|
|
|
> con <- connect "127.0.0.1" [SlaveOK]
|
|
|
|
Getting the Databases
|
|
------------------
|
|
|
|
> dbs <- databaseNames con
|
|
> let testdb = head dbs
|
|
|
|
|
|
Getting the Collections
|
|
-----------------------
|
|
|
|
> collections <- collectionNames con testdb
|
|
> let testcol = head collections
|
|
|
|
Documents
|
|
---------
|
|
|
|
BSON representation in Haskell
|
|
|
|
Inserting a Document
|
|
-------------------
|
|
|
|
> insert con testcol (toBsonDoc [("author", toBson "Mike"), ("text", toBson "My first Blog post!"), ("tags", toBson ["mongodb", "python","pymongo"])])
|
|
|
|
|
|
Getting a single document with findOne
|
|
-------------------------------------
|
|
|
|
> findOne con curcol (toBsonDoc [("author", toBson "Mike")])
|
|
|
|
Querying for More Than One Document
|
|
------------------------------------
|
|
|
|
> cursor <- find con curcol (toBsonDoc [("author", toBson "Mike")])
|
|
|
|
> allDocs cursor
|
|
|
|
See nextDoc to modify cursor incrementally one at a time.
|
|
|
|
* Note: allDocs automatically closes the cursor when done, through nextDoc.
|
|
|
|
|
|
Counting
|
|
--------
|
|
|
|
We can count how many documents are in an entire collection:
|
|
|
|
> num <- count con testcol
|
|
|
|
Or we can query for how many documents match a query:
|
|
|
|
> num <- countMatching con testcol (toBsonDoc [("author", toBson "Mike")])
|
|
|
|
Range Queries
|
|
-------------
|
|
|
|
No non native sorting yet.
|
|
|
|
Indexing
|
|
--------
|
|
|
|
WIP - coming soon.
|
|
|
|
Something like...
|
|
> index <- createIndex con testcol [("author", Ascending)] True
|