CODEWITHSUNDEEP
ruby-on-railsrubyrails-migrations
niaomingjian
niaomingjian

Reputation: 3742

How to undo the action of rails db:migrate in Rails 5.0.0.1

When migrating the database, I made a spelling mistake.

I want to generate a scaffold by running: 

rails generate scaffold Micropost context:text user_id:integer
rails db:migrate

Although I made a mistake by leaving out the colon when I ran: 

rails generate scaffold Micropost context:text user_id integer
rails db:migrate

I want to undo this migration, how to do it? (I'm using Rails 5.0.0.1)

When I run rails db:migrate, I get an error of: 

 SQLite3::SQLException: table "microposts" already exists:

When I run rails db:migrate:status, I get the following output: 

 Status   Migration ID    Migration Name  
 up       20161024021157  Create users  
 up       20161024025545  ********** NO FILE **********  
 down     20161024025805  Create microposts

I tried to use rails db:migrate:down VERSION=20161024025805. There wasn't any message showing in the command line. Then I ran rails db:migrate. The error is the same.

Upvotes: 1

Views: 3040

Answers (1)

Luka Kerr
Luka Kerr

Reputation: 4239

rails db:rollback will simply rollback one migration which I believe is what you are looking for

For a more specific rollback, you can run rails db:migrate:down VERSION=numberofversion

Replace the numberofversion with the version number of the migration file generated, for example:

rails db:migrate:down VERSION=1843652238

Edit:

Since you are getting the error that the Microposts table already exists, you must follow these steps to remove the table:

  1. Run rails generate migration DropMicroposts
  2. Go to the /db/migrate folder and find the latest migration file you just created

  3. In that file paste this: 

    class DropMicroposts < ActiveRecord::Migration 
  def up 
    drop_table :microposts 
  end 
end

  4. run rails db:migrate

  5. After this, run rails generate scaffold Micropost context:text user_id:integer
  6. Then run rails db:migrate

Upvotes: 5

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