Question

I’m building an application that will require CouchDB’s mobile syncing feature.

So for each ‘account’ on the service I want to create a separate CouchDB database instance so that only this account’s data is synced.

I’m using CouchRest Model and Devise, which handles subdomain authentication via a separate users database.

However what is the correct way to connect to the appropriate database at runtime for each model?

A before_filter that sets up a named connection, then loops through each model and does something like this: ?

[Post, Tag, Comment].each do |model|
  model_server = CouchRest::Server.new(couch_config[:connection])
  model_server.default_database = "my_project-#{Rails.env}-#{model.to_s.downcase}"    
  model.database = model_server.default_database
end

(Pseudocode)

Assuming that the web server (Heroku) runs each request in a separate thread, this should mean that on each request, the database connection is changed dynamically.

Seems like there should be an easier way!

Answer 1

As a solution to question you can override the database method:

class OneDbPerAccountDocument < CouchRest::ExtendedDocument

  def self.database
    Account.current_database
  end
  ...
end

And then just subclass your models (Post, Tag, Comment) from this class.

class Account < OneDbPerAccountDocument

  def self.current=(name)
    @current_database = @couch_server.database("my-project_#{name}")
  end

  def self.current_database
    @current_database
  end

end

With this trick all you need to do in controller is just call something like

  Account.current = request.subdomain

But, beware that this approach will become a little messy when you’ll have several thousands of accounts (databases).