CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3sqlite
ibylich
ibylich

Reputation: 658

Rails append database

Is it possible to append two databases in rails application? For example, SQLite database is portable. I can download SQLite database from another server. When rails application starts, it mount the database. Can i append all the data from another database to existing database? May be SQLite provide a way for merging databases?

Upvotes: 1

Views: 226

Answers (2)

Fábio Batista
Fábio Batista

Reputation: 25270

If you want to "seed" your database with data from an external source, like a central location, your best bet is to:

  • Provide such data into a easy to iterate format (like CSV, JSON or YAML);
  • Merge this data into your database on your app's initialization, providing it does not exist.

I do something like this on some projects. I would not, however, perform the merge automatically: I'd rather use the db/seeds.rb file and the rake db:seed task:

if State.count == 0
  State.transaction do
    CSV.foreach("#{::Rails.root}/db/seed_data/states.csv", 'r') do |row|
      code, acronym, name = *row
      State.create! code: code, acronym: acronym, nane: name
    end
  end
end

In this code I load the data from a local file, but you can easily change to a remote file using Net::HTTP.

Upvotes: 1

cutalion
cutalion

Reputation: 4394

I'm not sure sure what did you mean saying "append databases in application". But you can use 2 different (with different schemes) databases in your application. For example:

config/database.yml

development:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: project_dev
  pool: 5
  username: project
  password:

test:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: project_test
  pool: 5
  username: project
  password: 

sqlite:
  development:
    adapter: sqlite3
    database: db/development.project.db
    pool: 5
    timeout: 5000

  test:
    adapter: sqlite3
    database: db/test.project.db
    pool: 5
    timeout: 5000

Models:

Abstract model for all sqlite models; uses connection ninja gem

class SqliteModel < ActiveRecord::Base
  self.abstract_class = true
  use_connection_ninja(:sqlite)
end

Sqlite model

class Book < SqliteModel
  set_table_name  :Books
  set_primary_key :BookID

  belongs_to  :volume,  :foreign_key => :VolumeID
  has_many :chapters,   :foreign_key => :BookID
end

Mysql model

class Highlight < ActiveRecord::Base
  # ...
end

You can even use associations between tables in different databases.

But if you was asking about using 2 databases with the same scheme(i.e. just different data), then my answer is no, it's not possible(I can be wrong though). I think that is a question about replication, synchronization, backups or something similar - DB layer, not application.

Of course you can have 2 same tables in both databases, 2 models - one per database, and then just copy records from one to another. But Rails won't do it automatically.

Upvotes: 2

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