change_column produces bad SQL on Postgres

[jkutner]

The following migration:

 modify_table :persons do
    change_column :name, String, :length => 255
 end

Produces this invalid SQL on PostgreSQL (version 8.4):

ALTER TABLE "persons" ALTER COLUMN "persons" TYPE "name" VARCHAR(255)

It should produce:

ALTER TABLE "persons" ALTER COLUMN "name" TYPE  VARCHAR(255)

System info:
jruby 1.6.1 (ruby-1.8.7-p330) (2011-04-12 85838f6) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_24) [darwin-x86_64-java]
postgres (PostgreSQL) 8.4.4

[bascht]

Trapped into the same pit, when I was trying to add an Enum to a class.
Probably related to #30. Steps to reproduce:

require 'dm-core'
require 'dm-types'
require 'dm-migrations'
require 'dm-migrations/migration_runner'

DataMapper::Logger.new(STDOUT, :debug)
DataMapper.setup(:default, "postgres://user:pass@localhost:5432/mydb")

class Switch
  include DataMapper::Resource
  property :id, Serial
end

DataMapper.auto_migrate!

migration 1, :add_enum_value do
  up do
    modify_table :switches do
      add_column :state, Enum[:off, :on, :broken], :default => :off
    end
  end
end

DataMapper.migrate_up!

results in:

ALTER TABLE "switches" ADD COLUMN "state" INTEGER DEFAULT 'off'

I'd be happy to help. Let me know I can supply more information.

[tlianza]

Similar boat here... in my case I actually want to leave the column type the same, but add it as part of the primary key. Seems the syntax doesn't allow that, and I need to re-specify the datatype, which then causes this issue.

[jalcine]

I get the same problem here when attempting to increase the length of a String field. Has anyone a patch or suggestions on fixing this?

[jalcine]

For now, I've managed to get around this problem by explicitly adding 'type' into the migration statements. For example:

migration 50, :increase_size_of_events_title do
  up do
    modify_table :events do
      change_column :title, 'type varchar', size: 100
    end
  end

  down do
    modify_table :events do
      change_column :title, 'type varchar', size: 50
    end
  end
end

I'd take a look later as to where this statement has to be updated (or if this is something that has to be overwritten). I'm not sure if this is a PostgreSQL specific syntax bug.

[jalcine]

So I've noticed a similar problem when attempting to update the falsifiability of the null state of a column, I'd have to do this to have proper SQL generated.

migration 20, :prevent_empty_on_column_address_in_galleries do
  up do
    Site::Models::Gallery.all do |gallery|
      if gallery.address.empty?
        gallery.address = 'New York, New York, United States'
        gallery.save
      end
    end
    modify_table :galleries do
      # NOTE: Use 'set' to change state, no need for type information.
      change_column :address, 'set', allow_nil: false
    end
  end

  down do
    modify_table :galleries do
      # NOTE: Use 'set' to change state, no need for type information.
      change_column :address, 'set', allow_nil: true
    end
  end
end