Ruby on Rails Custom Migration Generator

Question

I\'m creating a Rails gem that integrates closely with Active Record. The gem requires a number of fields to be defined. For example:

class User < ActiveRecor         


        

Answer 1

Actually if you call

rails g model profile name:string next:attached

rails allready generates you a migration with

def self.up
  create_table :profiles do |t|
    t.string :name
    t.attached :next

    t.timestamps
  end
end

however you can override the default migration template by placing it in /lib/templates/active_record/model/migration.rb

You should write a rake my_gem:setup task to put the file there I haven't tried, but i guess rails does not search in non-engine gems for these templates

Your migration template contents would then look like

class <%= migration_class_name %> < ActiveRecord::Migration
  def self.up
    create_table :<%= table_name %> do |t|
<% for attribute in attributes -%>
  <% if attribute.type.to_s == "attached" %>
      t.string :<%= attribute.name %>_identifier
      t.string :<%= attribute.name %>_extension
      t.integer :<%= attribute.name %>_size
  <% else %>
      t.<%= attribute.type %> :<%= attribute.name %>
  <% end %>
<% end -%>
<% if options[:timestamps] %>
      t.timestamps
<% end -%>
    end
  end

  def self.down
    drop_table :<%= table_name %>
  end
end