Hello Edgar, thanks for your answer. We are evaluating ADS for the purpose of migrating an old Clipper-App to Rails. The code is really just a one-liner - here is the code together with the output. I could not manage to attach a binary file - so here is a link to the dbf file http://www.freakout.de/fkselb/emps.dbf - good luck - by the way - we discovered more problems - ruby complains when 8-bit OEM-charset data is assigned to - when we have a documented testcase we will ask the next question.

#!/opt/ruby/bin/ruby
ENV['GEM_PATH'] = '/opt/rubygem/gems:/opt/rails'
require 'active_record'

ActiveRecord::Base.establish_connection(  
    :adapter  => 'advantage',
    :database => '/home/axel/p/axbase/data',
    :username => '',
    :password => '',
    :options  => 'ServerType=ADS_LOCAL_SERVER; TableType=ADS_CDX;'
)

class Emp < ActiveRecord::Base  
  self.table_name = "emps"
  self.primary_key = "empno"
end

puts Emp.first.to_yaml
Emp.all.each {|e| puts e.to_yaml}

Output:

--- !ruby/object:Emp
attributes:
  EMPNO: 7369.0
  ENAME: 'SMITH          '
  JOB: 'CLERK       '
  MGR: 7902.0
  HIREDATE: 1980-12-17
  SAL: 800.0
  COMM: 0.0
  DEPTNO: 20.0
/opt/rails/gems/activerecord-advantage-adapter-0.1.1
/opt/ruby/lib/ruby/2.1.0/bigdecimal/util.rb:60:in `BigDecimal': string contains null byte (ArgumentError)
    from /opt/ruby/lib/ruby/2.1.0/bigdecimal/util.rb:60:in `to_d'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/connection_adapters/column.rb:190:in `value_to_decimal'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/attribute_methods/read.rb:84:in `__temp__'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/attribute_methods/read.rb:46:in `type_cast_attribute'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/attribute_methods/read.rb:127:in `read_attribute'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/attribute_methods.rb:185:in `block in attributes'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/attribute_methods.rb:185:in `each'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/attribute_methods.rb:185:in `attributes'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/base.rb:581:in `encode_with'
    from /opt/ruby/lib/ruby/2.1.0/psych/visitors/yaml_tree.rb:485:in `dump_coder'
    from /opt/ruby/lib/ruby/2.1.0/psych/visitors/yaml_tree.rb:146:in `accept'
    from /opt/ruby/lib/ruby/2.1.0/psych/visitors/yaml_tree.rb:112:in `push'
    from /opt/ruby/lib/ruby/2.1.0/psych.rb:409:in `dump'
    from /opt/ruby/lib/ruby/2.1.0/psych/core_ext.rb:14:in `psych_to_yaml'
    from /opt/rails/gems/activerecord-3.2.13/lib/active_record/base.rb:654:in `to_yaml'
    from ./test_dbs_rby_ard_ads.run:21:in `block in <main>'
    from ./test_dbs_rby_ard_ads.run:21:in `each'
    from ./test_dbs_rby_ard_ads.run:21:in `<main>'

Dear Edgar, ruby 1.9.x/rails 3.0.x is not an option for us. Way too old. The whole adapter is not compatible with Rails4. Is there any chance that this wonderful piece of software will be maintained to support current versions? Cheers Axel

Since the ruby/activerecord interface is a feature of the product mentioned in the release notes it should be maintained to support current versions - rails-3.0 is more than 3 years old. i have managed to use it with rails-3.2.13/ruby-2.1.3 (last rails3 version no chance with rails4) with this patch:

--- gems/activerecord-advantage-adapter-%{railsadvantage}/lib/active_record/connection_adapters/advantage_adapter.rb        Mon Oct 27 14:13:47 2014
+++ gems/activerecord-advantage-adapter-%{railsadvantage}/lib/active_record/connection_adapters/advantage_adapter.rb        Mon Oct 27 14:27:48 2014
@@ -381,6 +381,8 @@
     WHEN type_name = 'VARCHAR' or type_name = 'CHAR' or type_name = 'CICHAR' or
          type_name = 'NVARCHAR' or type_name = 'NCHAR' or type_name = 'VARBINARY'
          THEN CAST(TRIM(type_name) + '(' + TRIM(CAST(column_size AS SQL_CHAR)) + ')' AS SQL_CHAR)
+    WHEN type_name = 'NUMERIC' and decimal_digits = 0
+         THEN CAST('INTEGER(' + TRIM(CAST(column_size AS SQL_CHAR)) + ')' AS SQL_CHAR)
     WHEN type_name = 'NUMERIC' or type_name = 'DOUBLE' or type_name = 'CURDOUBLE'
          THEN CAST(TRIM(type_name) + '(' + TRIM(CAST(column_size AS SQL_CHAR)) + ',' + TRIM(CAST(decimal_digits AS SQL_CHAR)) + ')' AS SQL_CHAR)
     ELSE
@@ -448,7 +450,7 @@
         # Nullability is returned as 0 (no nulls allowed) or 1 (nulls allowed)
         # Alos, ActiveRecord expects an autoincrement column to have default value of NULL
         def table_structure(table_name)
-          sql = "SELECT COLUMN_NAME, IIF(COLUMN_DEF = 'NULL', null, COLUMN_DEF) as COLUMN_DEF, TYPE_NAME, NULLABLE from (EXECUTE PROCEDURE sp_GetColumns( NULL, NULL, '#{table_name}', NULL )) spgc where table_cat <> 'system';"
+          sql = "SELECT COLUMN_NAME, IIF(COLUMN_DEF = 'NULL', null, COLUMN_DEF) as COLUMN_DEF, IIF(TYPE_NAME = 'NUMERIC' and DECIMAL_DIGITS = 0, 'INTEGER', TYPE_NAME) as TYPE_NAME, NULLABLE from (EXECUTE PROCEDURE sp_GetColumns( NULL, NULL, '#{table_name}', NULL )) spgc where table_cat <> 'system';"
           structure = execute(sql, :skip_logging)
           raise(ActiveRecord::StatementInvalid, "Could not find table '#{table_name}'") if structure == false
           structure
@@ -514,7 +516,11 @@
               max_cols = ADS.instance.api.ads_num_cols(rs)
               result = Hash.new()
               max_cols.times do |cols|
-                result[ADS.instance.api.ads_get_column_info(rs, cols)[2]] = ADS.instance.api.ads_get_column(rs, cols)[1]
+                cinfo = ADS.instance.api.ads_get_column_info(rs, cols)
+                cvalu = ADS.instance.api.ads_get_column(rs, cols)[1]
+                cvalu = '0.0' if cinfo[3] == 13 and cvalu.rstrip == ''
+                cvalu.rstrip! if cinfo[3] == 2 and cvalu
+                result[cinfo[2]] = cvalu
               end
               record << result
             end