[jruby-dev] [jira] Created: (JRUBY-1905) ALTER TABLE failure using jdbcderby during rails migration adding a column with 'not null' constraint

[Stephen Bannasch (JIRA)]

ALTER TABLE failure using jdbcderby during rails migration adding a column with 
'not null' constraint
-----------------------------------------------------------------------------------------------------

                 Key: JRUBY-1905
                 URL: http://jira.codehaus.org/browse/JRUBY-1905
             Project: JRuby
          Issue Type: Bug
          Components: ActiveRecord-JDBC
    Affects Versions: JRuby 1.1
         Environment: MacOS X 10.4.11, Java 1.5.0_13, JRuby trunk r5512, rails 
2.0.2, activerecord-jdbc-adapter 0.7.1, activerecord-jdbcderby-adapter 0.7.1
            Reporter: Stephen Bannasch


Migrating a set of migrations from mysql to derby I found that I couldn't 
create columns in a derby database with a 'NOT NULL' constraint unless I also 
set a default value. 

It is common in rails apps to set ":null => false" as a column constraint 
without specifying a default value.

Perhaps this is not an error in the jdbcderby adaptor but instead a function of 
how Derby itself operates.

Here's a simple test case.

Create a simple rails testapp:

{code}
$ rails testapp --database mysql
{code}

Edit config/database.yml  to use derby instead of mysql:

{code}
$ cat config/database.yml 
development:
  adapter: jdbcderby
  database: db/development.derby
  timeout: 5000

test:
  adapter: jdbcderby
  database: db/test.derby
  timeout: 5000

production:
  adapter: jdbcderby
  database: db/production.derby
  timeout: 5000
{code}

Create a scaffold with a migration:

{code}
$ jruby script/generate scaffold widget name:string description:text
{code}

Here's what the schem looks like now:

{code}
$ cat db/schema.rb                
ActiveRecord::Schema.define(:version => 1) do

  create_table "widgets", :force => true do |t|
    t.string    "name"
    t.text      "description"
    t.timestamp "created_at"
    t.timestamp "updated_at"
  end

end
{code}

Create a new migration adding a column:

{code}
$ cat db/migrate/002_add_field.rb 
class AddField < ActiveRecord::Migration
  def self.up
    add_column :widgets, :color, :string, :null => false
  end

  def self.down
    remove_column :widgets, :function
  end
end
{code}

The migration fails:

{code}
$ rake db:migrate
(in /Users/stephen/dev/jruby/rails/testapp)
== 2 AddField: migrating ======================================================
-- add_column(:widgets, :color, :string, {:null=>false})
rake aborted!
ActiveRecord::ActiveRecordError: In an ALTER TABLE statement, the column 
'COLOR' has been specified as NOT NULL and either the DEFAULT clause was not 
specified or was specified as DEFAULT NULL.: ALTER TABLE widgets ADD color 
varchar(256) NOT NULL
{code}

If instead a default value is added to the new column definition:

{code}
add_column :widgets, :color, :string, :null => false, :default => 'red'
{code}

The migration succeeds.



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