Question

I have successfully created a database and performed my first migration using:

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      t.string :name
      t.string :email

      t.timestamps
    end
  end
end

When I try to reset the database I get the following:

rake aborted!
can't convert nil into String

I’m unsure as to what could be causing this problem or how to debug it so any help would be appreciated.

I am running Rails 3.1

The full trace of the error is:

** Invoke db:reset (first_time)
** Invoke db:drop (first_time)
** Invoke db:load_config (first_time)
** Invoke rails_env (first_time)
** Execute rails_env
** Execute db:load_config
** Execute db:drop
** Invoke db:setup (first_time)
** Invoke db:create (first_time)
** Invoke db:load_config 
** Execute db:create
db/test.sqlite3 already exists
** Invoke db:schema:load (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute db:schema:load
-- create_table("users", {:force=>true})
   -> 0.0050s
-- initialize_schema_migrations_table()
   -> 0.0053s
-- assume_migrated_upto_version(20111212200427, ["/Users/xxxx/My_Work/Resources/Rails/Books/Rails-Tutorial/Sample-App/sample_app/db/migrate"])
   -> 0.0055s
** Invoke db:seed (first_time)
** Invoke db:abort_if_pending_migrations (first_time)
** Invoke environment 
** Execute db:abort_if_pending_migrations
** Execute db:seed
rake aborted!
can't convert nil into String
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.0/lib/rails/engine.rb:487:in `exist?'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.0/lib/rails/engine.rb:487:in `load_seed'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.1.0/lib/active_record/railties/databases.rake:299:in `block (2 levels) in <top (required)>'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `call'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:205:in `block in execute'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `each'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:200:in `execute'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:158:in `block in invoke_with_call_chain'
/Users/xxxx/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:176:in `block in invoke_prerequisites'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:174:in `each'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:174:in `invoke_prerequisites'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:157:in `block in invoke_with_call_chain'
/Users/xxxx/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:176:in `block in invoke_prerequisites'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:174:in `each'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:174:in `invoke_prerequisites'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:157:in `block in invoke_with_call_chain'
/Users/xxxx/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/task.rb:144:in `invoke'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:116:in `invoke_task'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `block (2 levels) in top_level'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `each'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:94:in `block in top_level'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:88:in `top_level'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:66:in `block in run'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/gems/rake-0.9.2.2/bin/rake:33:in `<top (required)>'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/bin/rake:19:in `load'
/Users/xxxx/.rvm/gems/ruby-1.9.3-p0/bin/rake:19:in `<main>'
Tasks: TOP => db:reset => db:setup => db:seed

Answer 1

It’s looking for db/seeds.rb, recreating an empty one will solve your problem:

touch db/seeds.rb