I've just started using mongoDB with rails 3.1.
I've looked at mongoid and mongomappers ORMs: some things seems to be not very straitforward
with ORMs, but I'm newbie to this, just wanted to know the opinion of the experienced users.
When is it a good idea to work with ORM like Mongoid and MongoMapper and where these ORMs do fail?
Actually in my application I use only REST interface when interacting with client (no ERB template views, just json objects), and I'm not sure if I need the interlayer (ORM) between mongodb (server data model) and my client data model, because I plan to have them pretty much the same.
Thanks!
Related
Can I use MongoDB and a PostgreSQL in one rails app? Specifically I will eventually want to use something like MongoHQ. So far I have failed to get this working in experimentation. And it concerns me that the MongoDB documentation specifically says I have to disable ActiveRecord. Any advice would be appreciated.
You don't need to disable ActiveRecord to use MongoDB. Check out Mongoid and just add the gem plus any models along side any of your existing ActiveRecord models. You should note that MongoHQ is just a hosting service for MongoDB and can be used alongside any Object Document Mapper (ODM).
For further details check http://mongoid.org/en/mongoid/docs/installation.html. Just skip the optional 'Getting Rid of Active Record' step.
On a recent client site I worked with a production system that merged MySQL and MongoDB data with a single Java app. To be honest, it was a nightmare. To join data between the two databases required complex Java data structures and lots of code, which is actually databases do best.
One use-case for a two database system is to have the pure transactional data in the SQL database, and the aggregate the data into MongoDB for reporting etc. In fact this had been the original plan at the client, but along the way the databases became interrelated for transactional data.
The system has become so difficult to maintain that is is planned to be scrapped and replaced with a MongoDB-only solution (using Meteor.js).
Postgres has excellent support for JSON documents via it's jsonb datatype, and it is fully supported under Rails 4.2, out of the box. I have also worked with this and I find it a breeze, and I would recommend this approach.
This allows an easy mix of SQL and NoSQL transactions, eg
select id, blast_results::json#>'{"BlastOutput2","report","results","search","hits"}'
from blast_caches
where id in
(select primer_left_blast_cache_id
from primer3_output_pairs where id in (185423,185422,185421,185420,185419) )
It doesn't offer the full MongoDB data manipulation features, but probably is enough for most needs.
Some useful links here:
http://nandovieira.com/using-postgresql-and-jsonb-with-ruby-on-rails
https://dockyard.com/blog/2014/05/27/avoid-rails-when-generating-json-responses-with-postgresql
There are also reports that it can outperform MongoDB on json:
http://www.slideshare.net/EnterpriseDB/the-nosql-way-in-postgres
Another option would be to move your Rails app entirely to MongoDB, and Rails has very good support for MongoDB.
I would not recommend running two databases, based on personal observations on how it can go bad.
We are using a dynamic attributes plugin similar to this:
http://codaset.com/joelmoss/dynamic-attributes
Which allows us to store dynamic attributes in our rails model. Those dynamic attributes are in a single database column. We are facing performance issues because of this and I am wondering if MongoId, MongoMapper or other rails plugins will allow us to keep some attribute in ActiveRecord (keeping the < ActiveRecord::Base) but store the dynamic attributes in mongodb. We want to do this because we need to keep using MySQL for most of our existing system, but use MongoDB to store dynamic attributes about some models.
Basically this is what I am talking about:
http://www.railsinside.com/plugins/242-quickly-add-couchdb-to-existing-rails-models-with-stuffing.html
This plugin does the exact same thing using CouchDB.
I don't see any reason that MongoDB can't handle the same thing.
MongoMapper should implement the ActiveRecord pattern. However, Mongo also has some simple drivers for Ruby. All in all, the concept of storing dynamic attributes is a perfect use-case for MongoDB.
If you don't mind skipping "ActiveRecord" you can probably cook up your own using the basic Mongo drivers with very little work.
If you can't figure out the steps to do this, I would suggest pinging the groups (http://groups.google.com/mongodb-user/) and asking Kyle Banker directly (he's their ruby expert).
MongoDB has two popular ORMs for Rails: MongoID and MongoMapper.
Are there CouchDB ORM:s for Rails 3?
I can't say for sure since I've never used it, but it looks like CouchRest would be the way to go - specifically "CouchRest Model" looks like has been updated to work with Rails3 ActiveModel.
FWIW, I landed on CouchRest after finding this thread.
there is couchRest as noted above, or if you like active record style try couch_foo. I had different needs when i was looking into couch this past spring, and using rails 3. Rails 3 should be ORM agnostic, so it shouldn't really mess with it, although I couldn't get testing to work easily, but that could have just been me.
I am considering using MongoDB (mongo-mapper) for a portion of my rails application. I am not ready to go whole hog MongoDB because there are too many useful gems that depend on a traditional DB.
That being said there are parts of my application that would be great to leverage a document database.
Has anyone had success mixing the two approaches? How do you link activerecord models with mongomapper models?
MongoMapper doesn't implement ActiveModel yet, but I think there are a few forks on github that do. You could use Mongoid instead (which does) and your relationships between Mongoid docs and ActiveRecord entries would just magically work. I know a number of people are doing that.
That said, I wouldn't want to mix them unless I absolutely had to have an RDBMS for some reason.
Here a presentation about this issue: http://nosql.mypopescu.com/post/541657350/presentation-blending-nosql-and-sql-at-confoo
I don't know ROR so I can't judge it is a good presentation.
http://railscasts.com/episodes/194-mongodb-and-mongomapper
http://www.mongodb.org/display/DOCS/Object+Mappers+for+Ruby+and+MongoDB
http://www.mongodb.org/display/DOCS/MongoDB+Data+Modeling+and+Rails
http://www.mongodb.org/display/DOCS/Ruby+Language+Center
You need to mixin mongomapper with the model class
This gives you freedom to define the key-value pairs other than activerecord
include MongoMapper::Document
Dead simple I think.
I'm looking for any pointers on how to write a rails web app without ActiveRecord.
A doc or an example of a (not too complex) web app using storage backends other than a relational database would be greatly appreciated.
It's not clear on what should be implemented in the model classes in order to make the rails app work without the ActiveRecord layer.
Thanks,
Of course it's possible, here, for example, MongoMapper is used instead of ActiveRecord:
http://railstips.org/blog/archives/2009/07/23/getting-started-with-mongomapper-and-rails/
Note that this will seem a lot easier with Rails 3. Rails team spent a lot of efforts on ORM agnosticism when pushing to beta. They've created a public API (ActiveModel) for different ORMs to implement, so that an ORM can serve as a drop-in replacement for ActiveRecord. That way you'll just be able to define models in terms of your ORM without any extra efforts.
DataMapper already has an implementation of ActiveModel in dm-rails, and there'll be more to come.
See this post by Yehuda Katz for details.