Example produces undefined method for nil exception

[chrisle]

I'm taking this gem for a test drive. Looks really interesting!

Environment

Ruby 1.9.3p194. Rails 3.2.6.

Steps to recreate:

1. I created a new rails application
2. Added mysql2, data_miner, and unicode_utils to the Gemfile and bundle installed
3. Created app/models/country.rb and pasted your example in.
4. Manually created a "countries" table in MySQL
5. Opened up the rails console, and typed "Country.run_data_miner!"

I got the following error. I also tried this in an existing app and got the same error.

Stacktrace

1.9.3p194 :001 > Country.run_data_miner!
   (0.2ms)  SELECT COUNT(*) FROM `countries` 
   (0.1ms)  BEGIN
  SQL (0.3ms)  INSERT INTO `data_miner_runs` (`aasm_state`, `created_at`, `error`, `model_name`, `row_count_after`, `row_count_before`, `stopped_at`, `updated_at`) VALUES ('limbo', '2012-07-12 13:28:46', NULL, 'Country', NULL, 0, NULL, '2012-07-12 13:28:46')
   (0.4ms)  COMMIT
   (0.1ms)  BEGIN
   (1.5ms)  UPDATE `data_miner_runs` SET `error` = 'undefined method `type\' for nil:NilClass\n/Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/data_miner-2.3.4/lib/data_miner/attribute.rb:357:in `boolean_column?\'\n/Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/data_miner-2.3.4/lib/data_miner/attribute.rb:268:in `read\'\n/Users/chrisle/.rvm/gems/ruby-1.9.3-  ...
   (1.0ms)  COMMIT
   (0.1ms)  SELECT COUNT(*) FROM `countries` 
   (0.0ms)  BEGIN
   (0.2ms)  UPDATE `data_miner_runs` SET `row_count_after` = 0, `stopped_at` = '2012-07-12 13:28:47', `updated_at` = '2012-07-12 13:28:47' WHERE `data_miner_runs`.`id` = 3
   (0.4ms)  COMMIT
NoMethodError: undefined method `type' for nil:NilClass
    from /Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/data_miner-2.3.4/lib/data_miner/attribute.rb:357:in `boolean_column?'
    from /Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/data_miner-2.3.4/lib/data_miner/attribute.rb:268:in `read'
    from /Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/data_miner-2.3.4/lib/data_miner/step/import.rb:92:in `block (2 levels) in start'
    from /Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/remote_table-2.0.2/lib/remote_table.rb:432:in `block (2 levels) in each'
    from /Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/remote_table-2.0.2/lib/remote_table.rb:421:in `each'
    from /Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/remote_table-2.0.2/lib/remote_table.rb:421:in `block in each'
    from /Users/chrisle/.rvm/gems/ruby-1.9.3-p194@test_drive_data_mining/gems/remote_table-2.0.2/lib/remote_table/delimited.rb:50:in `block in _each' 
....

Have you seen this before?

[seamusabshere]

the next version of the gem will tell you if a column doesn't exist - which is i think what happened here.

please let me know if using the new example from the readme fixed the issue.

[chrisle]

Works! It works when I had nothing in the database. Here is the example:

Loading development environment (Rails 3.2.6)
1.9.3p194 :001 > Country.run_data_miner!
   (8.2ms)  CREATE TABLE `data_miner_runs` (`model_name` varchar(255), `aasm_state` varchar(255), `created_at` datetime, `stopped_at` datetime, `updated_at` datetime, `error` text, `row_count_before` int(11), `row_count_after` int(11), `id` int(11) DEFAULT NULL auto_increment PRIMARY KEY) ENGINE=InnoDB
   (9.8ms)  CREATE INDEX `index_data_miner_runs_on_model_name` ON `data_miner_runs` (`model_name`)
   (8.0ms)  CREATE INDEX `index_data_miner_runs_on_aasm_state` ON `data_miner_runs` (`aasm_state`)
   (0.0ms)  BEGIN
  SQL (0.6ms)  INSERT INTO `data_miner_runs` (`aasm_state`, `created_at`, `error`, `model_name`, `row_count_after`, `row_count_before`, `stopped_at`, `updated_at`) VALUES ('limbo', '2012-07-12 17:01:10', NULL, 'Country', NULL, NULL, NULL, '2012-07-12 17:01:10')
   (0.2ms)  COMMIT
   (3.1ms)  CREATE TABLE `countries` (`iso_3166_code` varchar(255) PRIMARY KEY, `iso_3166_numeric_code` int(11), `iso_3166_alpha_3_code` varchar(255), `name` varchar(255)) ENGINE=InnoDB
   (0.0ms)  BEGIN
   (0.2ms)  UPDATE `data_miner_runs` SET `aasm_state` = 'succeeded', `updated_at` = '2012-07-12 17:01:11' WHERE `data_miner_runs`.`id` = 1
   (0.4ms)  COMMIT
   (0.2ms)  SELECT COUNT(*) FROM `countries` 
   (0.1ms)  BEGIN
   (0.2ms)  UPDATE `data_miner_runs` SET `row_count_after` = 249, `stopped_at` = '2012-07-12 17:01:11', `updated_at` = '2012-07-12 17:01:11' WHERE `data_miner_runs`.`id` = 1
   (0.2ms)  COMMIT
 => #<DataMiner::Run model_name: "Country", aasm_state: "succeeded", created_at: "2012-07-12 17:01:10", stopped_at: "2012-07-12 17:01:11", updated_at: "2012-07-12 17:01:11", error: nil, row_count_before: nil, row_count_after: 249, id: 1> 
1.9.3p194 :002 >