Rails迁移以删除字段

Question

Hello I am about to attempt to run a rails migration on a database of skills that has a :title and :description. I need to remove the description field and I assume it will look something like this:

rails migration remove_column :skills, :description

I am running it by you pros before I attempt it and end up breaking something on accident. Please let me know if I have the right idea about removing the description field from the database. Thanks a lot!

Answer 1

If skills is the name of your table and description is the name of the column you want to remove, you can type rails g migration RemoveDescriptionFromSkills in your terminal. This will generate a migration file with the name [timestamp]_remove_description_from_skills.rb , located in db/migrate . Edit this file so that it contains the following:

class RemoveDescriptionFromSkills < ActiveRecord::Migration
  def change
    remove_column :skills, :description
  end
end

Then type rake db:migrate in your terminal, and the column will be removed.

For more information, check out this helpful Stack Overflow post: https://stackoverflow.com/a/1992045/3723769 .

Note: this answer is intended to describe how to perform the migration. As a safety measure, you should do what Michael Durrant advises before migrating: https://stackoverflow.com/a/25006727/3723769 .

Answer 2

Here's some of the things that some to mind:-

• check the existing values to see if there's any data you want
• see if any indexes exist that should also be dropped.
• search the application for that field name
• see if there's an existing rails migration that you can use to DOWN the change

Finally, I would consider creating a change migration as normal, ie one that actaully adds the field and then I would run it using the down syntax to remove the field.