Today I Learned

A Hashrocket project

Use `reset_column_information` to Migrate Data

If you’re generating a Rails migration, chances are you might need to facilitate migrating data to a new column. You can use reset_column_information in a migration file to pick up your changes and immediately do something with those new columns.

Assuming we have 2 models, DraftPost and Post -

  class AddColumnDraftToPosts < ActiveRecord::Migration[5.2]
    def change
      add_column :posts, :draft, :boolean, default: true
      Post.reset_column_information
      DraftPost.all.each do |draft_post|
        Post.create(content: draftPost.content)
        draft_post.delete
    end
  end
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