What is the correct way to setup database with DataMapper and Sinatra on production server?
datamapper, ruby, sinatra, sqlite
Solution
Where and when should finalize be called?
From http://rdoc.info/github/datamapper/dm-core/DataMapper#finalize-class_method
This method should be called after loading all models and plugins.
When deploying the app first time there is no db file on the production server, how do I have it automatically created? Or do I have to create the project.db file manually?
It depends on your hosting arrangement, but the main thing to do is put the running of migrations in a Rake task and run them when the app is deployed. If you're using Sqlite, this would create the database (although on some hosts you are not allowed to update the file system). I don't think it's a good idea to use Sqlite for a production database, but that's your decision.
Since the auto_upgrade! is wrapped in :development block, it won't be called on production server. How am I supposed to upgrade database when I add or remove columns in it?
Use a Rake task. After each deployment you'd run the "db:migrate:up" (or whatever you'd called it) task and it would run the latest migrations. You might get a few ideas from Padrino's Rake tasks for DataMapper
Problem
From the DataMapper document, I think there are at least four functions need to be called to have database setup: ``` DataMapper.setup(:default, 'sqlite:///path/to/project.db') DataMapper.finalize DataMapper.auto_migrate! DataMapper.auto_upgrade! ``` In many DataMapper+Sinatra tutorials I learned that `auto_migrate!` and `auto_upgrade!` are not supposed to be called every time the app is loaded on production server. But in the meanwhile many examples call these functions in the main ruby file of the sinatra app, say `app.rb`, without additional check. And some examples do not call `finalize` at all. So far I am confused and I am not sure what to do on the production server. Take this following simple `app.rb` for example, I have some questions: - Where and when should `finalize` be called? - When deploying the app first time there is no `db` file on the production server, how do I have it automatically created? Or do I have to create the `project.db` file manually? - Since the `auto_upgrade!` is wrapped in `:development` block, it won't be called on production server. How am I supposed to upgrade database when I add or remove columns in it? ``` require 'sinatra' require 'data_mapper' configure do DataMapper.setup :default, "sqlite3://#{Dir.pwd}/project.db" end class Book include DataMapper::Resource property :id, Serial property :title, Text belongs_to :author end class Author include DataMapper::Resource property :id, Serial property :name, Text has n, :books end configure :development do DataMapper.auto_upgrade! end get '/:id' do @author = Author.get params[:id] erb :list_author_and_his_books # The template has nothing to do with this question, ignore it end get '/new' do # Some code for user to input book or author details end get '/create' do # Some code to create book or author in db end ``` Thanks for reading this long post :D