Table already exists error

[eye0rama]

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'
ActiveRecord::StatementInvalid: 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'
SQLite3::SQLException: table "articles_categories" already exists
/home/john/src/ror/blog/db/migrate/20161114230702_create_articles_categories.rb:3:in `change'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

I did some poking around in the rails console, and running: category.articles.empty?

Returned: NameError: undefined local variable or method `category' for main:Object

Is there a way I can fix this without just deleting everything and starting over?

[Colin Law]

On 16 November 2016 at 01:46, eye0rama <welcome.to...@gmail.com> wrote:

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

[Edsil Basadre]

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

[Colin Law]

On 16 November 2016 at 11:21, Edsil Basadre <eebas...@gmail.com> wrote:

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

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

Colin

[Edsil Basadre]

Thanks for correcting me Colin. :)

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[eye0rama]

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!