# HoboFields - Migration Generator Comments

Our test requires to prepare the testapp for a different environment:
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    doctest_require: ENV["RAILS_ENV"] = 'mysql_test'; 'prepare_testapp'

    >> system "cd #{TESTAPP_PATH} && rake db:setup"
    => true

    >> p Rails.env
    >>
     def nuke_model_class(klass)
       ActiveSupport::DescendantsTracker.instance_eval do
         class_variable_get('@@direct_descendants')[ActiveRecord::Base].delete(klass)
       end
      Object.instance_eval { remove_const klass.name.to_sym }
     end

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## Comments

Comments can be added to tables and fields with HoboFields.

    >>
     class Product < ActiveRecord::Base
       fields do
         name :string, :comment => "short name"
         description :string
       end
     end
    >> Rails.env
    => "mysql_test"
    >> Rails::Generators.invoke 'hobo:migration', %w(-n -m)

These comments will be saved to your schema if you have the [column_comments](http://github.com/bryanlarsen/column_comments) plugin installed.  If you do not have this plugin installed, the comments will be available by querying `field_specs`:

    >> Product.field_specs["name"].comment
    => "short name"

The plugin [activerecord-comments](http://github.com/bryanlarsen/activerecord-comments) may be used to get the comments from the database directly.  If the plugin is installed, use this instead:

    Product.column("name").comment

Because it will be quite common for people not to have both [column_comments](http://github.com/bryanlarsen/column_comments) and [activerecord-comments](http://github.com/bryanlarsen/activerecord-comments) installed, it is impossible for HoboFields to determine the difference between no previous comment and a previously missing plugin.   Therefore, HoboFields will not generate a migration if the only change was to add a comment.  HoboFields will generate a migration for a comment change, but only if the plugin is installed.

    >> require 'activerecord-comments'

    >> # manually add comment as the column_comments plugin would
    >> Product.connection.execute "alter table `products` modify `name` varchar(255) default null comment 'short name';"

    >>
     class Product < ActiveRecord::Base
       fields do
         name :string, :comment => "Short namex"
         description :string, :comment => "Long name"
       end
     end
    >> up, down = Generators::Hobo::Migration::Migrator.run
    >> up
    >> up.split(',').slice(0,3).join(',')
    => 'change_column :products, :name, :string'
    >> up.split(',').slice(3,2).sort.join(',')
    => " :comment => \"Short namex\", :limit => 255"


Cleanup
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    >> nuke_model_class(Product)
    >> ActiveRecord::Base.connection.execute "drop table `products`;"
    >> system "cd #{TESTAPP_PATH} && rake db:drop RAILS_ENV=mysql_test"
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