Add and Change the default value for table column with migration

Question

I currently have a migration and I simply want to add a couple more values to this migration such as to_limit and from_limit along with their default values (5&10). How should i do this?

class AddUserToCompany < ActiveRecord::Migration
  def change
    add_column :companies, :user, :jsonb, default: {"to_dist"=>50, "from_dist"=>70, "trs_one"=>100,   "trs_two"=>120}
  end
end

I added some changes which also requires "to_limit"=>5 and "from_limit"=>10. Please suggest on how to add a new migrate file and add the changes.

Rails version - 4.2.11

This is my first time working with a rails application. So i am really confused on how to proceed with this.

Hemangini Gohel · Accepted Answer · 2022-11-04 11:19:07Z

1

1.If this changes are in progress (not already used by other) then you can rollback this migration by command

rollback last migration

rake db:rollback STEP=1

In order to rollback ONLY ONE specific migration

rake db:migrate:down VERSION=20220905201547

and after applying changes, run rake db:migrate

If migration was created earlier then you can create new migration to apply your changes

generate new migration by command

rails generate migration nameOfMigration

I hope this helps

answered Nov 4, 2022 at 11:19

Hemangini Gohel

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2 Comments

Priyanshu0007 Over a year ago

The migration was created earlier so i will have to generate a new migration. I am a little confused regarding it. During the new migration do i add only the new details that i want to add or all of them including the existing ones. Need a small clarification regarding this. Thankyou

Hemangini Gohel Over a year ago

you can use change_column_default :articles, :user, from: {"to_dist"=>50, "from_dist"=>70, "trs_one"=>100, "trs_two"=>120}, to: {"to_dist"=>50, "from_dist"=>70, "trs_one"=>100, "trs_two"=>120, "new_att" => 10} I guess you need to pass all params as we can replace full the value(but may not be change anything with current value) @Priyanshu0007

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