require 'erb'
class ClientMigrator
def self.create(fields)
erb_migration = ERB.new <<-EOS
class AddClients < ActiveRecord::Migration
def self.up
create_table :clients do |t|
<% fields.each do |name, type| %>t.column :<%= name %>, :<%= type %>
<% end %>
end
end
def self.down
drop_table :clients
end
end
EOS
File.open("db/migrate/003_add_clients.rb", "w+") do |f|
f.puts erb_migration.result(binding)
end
`rake db:migrate`
end
end
# Example call
ClientMigrator.create(:name => :string, :phone => :string)
Refactorings
No refactoring yet !
Hampton
October 12, 2007, October 12, 2007 16:27, permalink
2 ratings.
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Hrrrm, this is a very confusing bit of code, because I believe the concept shown here is flawed from the start.... BUUUUUT
I wouldn't use migrations for this at all if I was going to do something as dirty as "dynamically" adding fields to a db with Rails.
This is assuming you just created a `clients` database with whatever default fields.
class ClientMigrator
def self.create(fields = {})
fields.each do |field, type|
ActiveRecord::Base.connection.add_column(:clients, type)
end
end
end
ClientMigrator.create(:name => :string, :phone => :string)
How do you create a rails project if you don't know the schema in advance? ERB to the rescue!
Blogged background: http://www.danielharan.com/2007/10/12/rails-migration-hackery-with-erb/