Add `:charset` and `:collation` options support for MySQL string and text columns

Example:

    create_table :foos do |t|
      t.string :string_utf8_bin, charset: 'utf8', collation: 'utf8_bin'
      t.text   :text_ascii,      charset: 'ascii'
    end

3 files changed, 43 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 9625fcf9b8..95bc60d891 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -13,6 +13,10 @@ module ActiveRecord
         end
       end
 
+      class ColumnDefinition < ActiveRecord::ConnectionAdapters::ColumnDefinition
+        attr_accessor :charset, :collation
+      end
+
       class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
         include ColumnMethods
 
@@ -23,8 +27,16 @@ module ActiveRecord
             column.type = :integer
             column.auto_increment = true
           end
+          column.charset = options[:charset]
+          column.collation = options[:collation]
           column
         end
+
+        private
+
+        def create_column_definition(name, type)
+          ColumnDefinition.new(name, type)
+        end
       end
 
       class Table < ActiveRecord::ConnectionAdapters::Table
@@ -60,6 +72,23 @@ module ActiveRecord
           add_column_position!(change_column_sql, column_options(o.column))
         end
 
+        def column_options(o)
+          column_options = super
+          column_options[:charset] = o.charset
+          column_options[:collation] = o.collation
+          column_options
+        end
+
+        def add_column_options!(sql, options)
+          if options[:charset]
+            sql << " CHARACTER SET #{options[:charset]}"
+          end
+          if options[:collation]
+            sql << " COLLATE #{options[:collation]}"
+          end
+          super
+        end
+
         def add_column_position!(sql, options)
           if options[:first]
             sql << " FIRST"
@@ -99,9 +128,18 @@ module ActiveRecord
         spec = super
         spec.delete(:precision) if /time/ === column.sql_type && column.precision == 0
         spec.delete(:limit)     if :boolean === column.type
+        if column.collation && table_name = column.instance_variable_get(:@table_name)
+          @collation_cache ||= {}
+          @collation_cache[table_name] ||= select_one("SHOW TABLE STATUS LIKE '#{table_name}'")["Collation"]
+          spec[:collation] = column.collation.inspect if column.collation != @collation_cache[table_name]
+        end
         spec
       end
 
+      def migration_keys
+        super + [:collation]
+      end
+
       class Column < ConnectionAdapters::Column # :nodoc:
         delegate :strict, :collation, :extra, to: :sql_type_metadata, allow_nil: true
 
diff --git a/activerecord/lib/active_record/connection_adapters/column.rb b/activerecord/lib/active_record/connection_adapters/column.rb
index a67127bd71..f4dda5154e 100644
--- a/activerecord/lib/active_record/connection_adapters/column.rb
+++ b/activerecord/lib/active_record/connection_adapters/column.rb
@@ -28,6 +28,7 @@ module ActiveRecord
         @null = null
         @default = default
         @default_function = default_function
+        @table_name = nil
       end
 
       def has_default?
diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
index da95920571..eaeaf0321b 100644
--- a/activerecord/lib/active_record/schema_dumper.rb
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -105,7 +105,10 @@ HEADER
       end
 
       def table(table, stream)
-        columns = @connection.columns(table)
+        columns = @connection.columns(table).map do |column|
+          column.instance_variable_set(:@table_name, table)
+          column
+        end
         begin
           tbl = StringIO.new