Add support for Mysql column positioning via #add_column and #change_column

add_column and change_column in the Mysql adapter now accept some
additional options:
:first => true        # Put the column in front of all the columns
:after => column_name # Put the colmn after 'column_name'

add_column :new_col, :string, :first => true
add_column :another_col, :integer, :default => 0, :after => :new_col

[#3286 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index ad36ff22e3..fa28bc64df 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -470,6 +470,13 @@ module ActiveRecord
         execute "RENAME TABLE #{quote_table_name(table_name)} TO #{quote_table_name(new_name)}"
       end
 
+      def add_column(table_name, column_name, type, options = {})
+        add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
+        add_column_options!(add_column_sql, options)
+        add_column_position!(add_column_sql, options)
+        execute(add_column_sql)
+      end
+
       def change_column_default(table_name, column_name, default) #:nodoc:
         column = column_for(table_name, column_name)
         change_column table_name, column_name, column.sql_type, :default => default
@@ -498,6 +505,7 @@ module ActiveRecord
 
         change_column_sql = "ALTER TABLE #{quote_table_name(table_name)} CHANGE #{quote_column_name(column_name)} #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
         add_column_options!(change_column_sql, options)
+        add_column_position!(change_column_sql, options)
         execute(change_column_sql)
       end
 
@@ -529,6 +537,13 @@ module ActiveRecord
         end
       end
 
+      def add_column_position!(sql, options)
+        if options[:first]
+          sql << " FIRST"
+        elsif options[:after]
+          sql << " AFTER #{quote_column_name(options[:after])}"
+        end
+      end
 
       # SHOW VARIABLES LIKE 'name'
       def show_variable(name)