Table already exists error

rubyonrails-talk
1

Hi all,

I have been learning Rails by working through Carneiro and Barazi’s Beginning Rails 3. This has went well despite the fact that I am using Rails 4.2.6. I hit a little snag when in chapter 5, which goes over associations, I tried to create a has_many association between a user and that user’s articles, specifically in the code that is supposed to sort the user’s articles first by order of creation, and then by alphabetical order. I fixed this problem, with a little help from the Ruby Talk mailing list, with a lambda scope block, as follows in app/models/user.rb:

  class User <

ActiveRecord::Base
has_one :profile
has_many :articles, → { order ‘published_at DESC, title ASC’ } :dependent => :nullify end

This seemed to work, so I went through the steps listed again, taking a stab that I could

overwrite everything rather than just starting over. When I ran rake db:migrate, I got the following error:

== 20161114230702 CreateArticlesCategories: migrating
2

Hi all,

I have been learning Rails by working through Carneiro and Barazi's *Beginning Rails 3*. This has went well despite the fact that I am using Rails 4.2.6. I hit a little snag when in chapter 5, which goes over associations, I tried to create a has_many association between a user and that user's articles, specifically in the code that is supposed to sort the user's articles first by order of creation, and then by alphabetical order. I fixed this problem, with a little help from the Ruby Talk mailing list, with a lambda scope block, as follows in app/models/user.rb:

class User < ActiveRecord::Base      has_one :profile      has_many :articles, -> { order 'published_at DESC, title ASC' } :dependent => :nullify end

This seemed to work, so I went through the steps listed again, taking a stab that I could overwrite everything rather than just starting over. When I ran rake db:migrate, I got the following error:

== 20161114230702 CreateArticlesCategories: migrating

-- create_table(:articles_categories, {:id=>false}) rake aborted! StandardError: An error has occurred, this and all later migrations canceled:

SQLite3::SQLException: table "articles_categories" already exists: CREATE TABLE

"articles_categories" ("article_id" integer, "category_id" integer)

/home/john/src/ror/blog/db/migrate/20161114230702_create_articles_categories.rb:3:in `change'

You are trying to run a migration (20161114230702_create_articles_categories.rb) that adds that table, but the table already exists in the database. Have you added a second migration that tries to add it again? If it is not that then the easiest solution may be to delete and recreate the db again.

Colin

3

Try to comment out the method that creating the table in migration 20161114230702_create_articles_categories.rb.

4

That is not really appropriate unless the OP understands why this has happened.

Colin

5

Thanks for correcting me Colin. :slight_smile:

6

I did not have a second migration trying to add it again, so I ran:

rake db:drop db:create db:migrate

``

I was able to do everything after that.

Thank you for the assistance!