Question

In my ROR project, I came across an issue. Previous developer of the project has save an array of data into a single column for a particular field. But now I have to get those data and save it to another separate table with the current table id. Following is my code for get the details from the db:

@ar = AResponse.select("id, selected_barriers");
    @ar.each do |p|
      p.selected_barriers.each do |barrier|

      end
    end

What I wanted is I have to save the p.id and barrier to a new table and I have to do it in a migration file. So when the migration runs, it will get all the existing details from AResponse and save it to the new one. Can I do it only with migration file? If so how can I do it?

This is my full code

I tried but its not working: Following is my code

class AnalysisBarriers < ActiveRecord::Migration
  def self.up

  end

  def change
    create_table :analysis_barriers do |t|
      t.integer :analysis_response_id, :null => false
      t.string :barrier
    end
    @analysis_response = AnalysisResponse.select("id, selected_barriers");
    @analysis_response.each do |p|
      p.selected_barriers.each do |barrier|
        AnalysisBarriers.create(:analysis_response_id => p.id, :barrier => barrier)
      end
    end
  end
  def self.down
    drop_table :analysis_barriers
  end
end

Thanks

Answer 1

Yes you can do data changes after migrations. Whatever data changes you want to do, you can do in change function or up function. Take the following example

class Event < ActiveRecord::Migration
  def change
    create_table events do |t|
      t.datetime :starts_at
      t.datetime :ends_at
      t.timestamps
    end
    Event.create(:starts_at => Time.now, :ends_at => Time.now+1)
  end
end

Above statement will add data to your table just after its creation.